6th Spanish Workshop in - digital.csic.es

6th Spanish

Workshop in

Nanolithography

Zaragoza, Spain.

28-30 October 2014.

Edited by:

http://unizar.es/nanolito

Colabora:



SCIENTIFIC PROGRAM

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6th Spanish Workshop in Nanolithography Zaragoza, Spain. 28-30 October 2014.

Day 1 TUESDAY, OCTOBER 28 Page

15:00‐15:30 REGISTRATION

15:30‐15:40 Opening words

15:40‐16:20 (invited talk)

Chairman of the session: Francesc Perez‐Murano

Ivo Rangelow Scanning Probe Lithography for beyond CMOS devices

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16:20‐17:20 (oral contr.) 20’each

Yu Kyoung Ryu Fabrication of sub‐12 nm thick silicon nanowires by processing scanning probe lithography masks

Ramón Bernardo Gavito E‐beam assisted etching and patterning of few‐layer molybdenum disulfide

Oihana Txoperena Deterministic transfer of two‐dimensional materials to fabricate electronic and spintronic devices

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17:20 Coffee break

17:20‐18:30 POSTER SESSION

19:00 Raith Users’ Meeting

SCIENTIFIC PROGRAM

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Day 2 WEDNESDAY, OCTOBER 29 Page


Chairman of the session: Santos Merino

Rainer Hillenbrand Nanofabrication for nanophotonics

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09:40‐11:00 (oral contr.) 20’each

Hanbin Zheng Plasmonic nanostructured materials by bottom up self assembly of colloids

Ana Conde Plasmonic hollow cylindrical nanostructures fabricated by Nanoimprint Lithography and non‐directional metallization

Tiberio Ezquerra Gold/Polymer nanogratings fabricated by Nanoimprint Lithography for application as Surface Enhanced Raman Scattering sensors

Deitze Otaduy Label‐Free Biosensor based on Localized Surface Plasmon Resonance

with custom microfluidic solution for TNF detection

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11:00‐11:30 Coffee break


Chairman of the session: José Ignacio Martín

Amalio Fernández Pacheco Probing three‐dimensional spintronic nanstructures

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12:10‐13:30 (oral contr.) 20’each

Luis Serrano‐Ramón Electron beam induced deposition of high‐purity and high‐aspect‐ratio three‐dimensional cobalt structures

Lorena Marín Magnetotransport in Nanopatterned La2/3Ca1/3MnO3 Nanowires

Jordi LLobet Electromechanical transduction in silicon nanowire mechanical resonators fabricated by focused ion beam (FIB) implantation

Maria Carmen Pallarés Integration of Molecular Magnets, Biomolecules and Nanoparticles on Devices

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13:30‐15:00

LUNCH AT TORRES QUEVEDO BUILDING CAFETERIA

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Day 2 AFTERNOON SESSION Page


Chairman of the session: José Luis Vicent

Isabel Rodríguez Topographical and chemical patterning of functional surfaces

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15:40‐17:00 (oral contr.) 20’each

Laura Evangelio Directed self‐assembly of block copolymers by chemical surface modification

Fernando Valdés‐Bango Tailoring of nanostructure in thin films through control of self‐assembled block‐copolymers morphology by small molecules hosting

Vito Clericò Top‐Down approach for Water Dispersible Three‐Dimensional LC‐Nanoresonators

Javier del Valle Nanostructuration as a way to induce a vortex smectic phase in Nb thin films

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17:30‐19:30

Chairman of the session: Javier Sesé

INDUSTRIAL SESSION

17:30

17:55

18:20

18:45

19:05

Laia Vilar (Cetemmsa technological Center) Printed Electronics from an industrial perspective

Philippe Godignon (CNM‐Barcelona) Epitaxial graphene on SiC substrates: growth and properties

Chengge Jiao (FEI) Dual Beam Nanoprototyping using Nanobuilder

Vincent Morin (Raith) Ion Column and Source technology employing Gallium and New Ion Species for Advanced FIB Nanofabrication

Peter Gnauck (Zeiss) Helium Ion Microscopy‐Advancement from 0.35 nm Imaging to Sub 10 nm patterning

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21:00 WORKSHOP DINNER

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Day 3 THURSDAY, OCTOBER 30 Page

09:30‐10:50 (oral contr.) 20’each

Chairman of the session: Luis Hueso

Soraya Sangiao Electrical detection of ferromagnetic resonance in nanostructures

Miren Isasa Detection of the spin Hall effect using lateral spin valves

Cristina López Thermal characterization of Permalloy nanostripes under short pulsed current excitation

Enrique Díez Quantum Phase transitions in h‐BN/graphene/h‐BN heterostructures

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CHANGE OF LOCATION TO “SALÓN DE ACTOS” AT BETANCOURT BUILDING

Chairman of the session: José María De Teresa

Albert Fert A new direction for spintronics: spin‐orbitronics and magnetic skyrmions

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13:00

Mesa Redonda Radiografía de la Investigación en España y Aragón

END OF THE WORKSHOP

14:00 LUNCH AT TORRES QUEVEDO BUILDING CAFETERIA

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POSTERS

Order Author/Title Page

P1

María José Pérez‐Roldán: “Fabrication and cross section investigation of FEBID Co‐SiOx binary systems“

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P2

Ismael García Serrano: “Transport measurements of W‐based superconducting films with thickness modulation grown by Focused‐Ion‐Beam Induced Deposition“

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P3

Juan Carlos González Rosillo: “Resistive Switching phenomena in La1‐xSrxMnO3‐x compounds: A local probe microscopy study“

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P4

Luis Ruiz‐Valdepeñas: “Fabrication of superconducting/magnetic bilayers with periodic thickness modulation in the magnetic component to study anisotropic dissipation“

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P5

Fernando Gálvez: “Fabrication and characterization of magneto‐plasmonic nanostructures arrays patterned by electron beam lithography“

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P6

Maite Goiriena‐Goikoetxea: “Self‐assembled Permalloy nanodisks for biomedical applications“

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P7

Aurora Nogales: “Nanostructuring Thin Polymer Films with 2 and 3‐Beam Single Pulse Laser Interference Lithography“

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P8 EstitxuVillamor: “Effect of oxygen on EBID deposited platinum structures“

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P9

Aritz Retolaza: “Perylendiimide‐based second‐order Distributed Feedback Lasers fabricated by Thermal Nanoimprint Lithography“

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P10

Inés Serrano‐Esparza: “Lithography techniques for graphene‐based nanodevices“

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P11

Maria Pilar Pina: “Standardization of deposition techniques for SnO2 nanoparticles on microhoplates for gas sensing applications“

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P12

Francisco Espinosa: “Fabrication of a thin layer MoS2 field effect transistor by oxidation scanning probe lithography“

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P13 Felipe Viela: “Mechano‐selective bacteria surface adhesion“

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P14

Libe Arzubiaga: “Fabricating devices beyond the limits of electron beam lithography“

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P15

Cristina Blanco‐Roldán: “Control of magnetic domain wall motion in Co microwires by tridimensional e‐beam lithographied structures“

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P16

Álvaro Rodríguez‐Rodríguez: “Laser Induced Periodic Surface Structures (LIPSS) on Semiconducting Polymers: Poly(3‐alkylthiophene)“

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P17 Juan José Morales: “W‐based nanowires grown by FEBID as temperature sensors for cryogenic picocalorimetry“

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P18 Edna Corredor: “Transversal orientation of the magnetization in Cu/Ni/Cu patterned rings and lines“

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P19 José María De Teresa: “Arrays of densely‐packed isolated nanowires by Focused Beam Induced Deposition plus Ar+ milling“

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P20

Albert Romano‐Rodríguez: “Focused Electron and Focused Ion Beam Induced Processing as tools for nanodevice fabrication: from basics to prototype fabrication and testing“

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P21

Alberto Álvarez‐Fernández : “Tailoring of nanostructure in thin films through control of self‐assembled block‐copolymers morphology by small guest molecules“

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INTRODUCTION

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Dear participant of the 6th Spanish Workshop in Nanolithography,

It is a great pleasure to welcome you and wish you a fruitful and exciting stay in Zaragoza. The five-century-old University of Zaragoza, through the Laboratorio de Microscopías Avanzadas-Instituto de Nanociencia de Aragón (LMA-INA) and the Instituto de Ciencia de Materiales de Aragón (ICMA, CSIC-University of Zaragoza), will host this workshop, which is the sixth one of a series of workshops previously held in Zaragoza in 2007, Barcelona in 2008, Madrid in 2009, Oviedo in 2010 and San Sebastián in 2012. These workshops have been organized in the framework of the NANOLITO network, which is the Spanish network on Nanolithography. Nanolithography comprises the set of techniques that allow the creation of nanodevices based on top-down approaches, and, therefore, it is a key element in Nanotechnology. The network is currently funded by the Ministry of Economy in Spain, with more details being found at www.unizar.es/nanolito. As a summary, we can mention that this network is formed by more than 50 research groups and supported by a few research centers and companies. Besides workshops, the network has organized two Summer Schools in Jaca (2011 and 2013) and has developed a program of short stays to foster collaboration between groups.

The 6th Spanish Workshop in Nanolithography will be held from 28th to 30th October 2014. The aim of this workshop is to strengthen the research in this field, sharing and exchanging the knowledge of the different Spanish teams working on this topic although some contributions from foreign laboratories have also been received. The workshop will focus on:

Electron-beam lithography Ion-beam lithography Electron-beam and ion-beam induced deposition and processing Nanoimprint and soft lithography Local probe lithography Self assembly Physical and chemical devices requiring nanolithography Industrial applications using nanolithography

The Scientific Program Committee of the 6th Spanish Workshop in Nanolithography is formed by Clivia Sotomayor (ICN2, Barcelona), José Luis Vicent (UCM, Madrid), Carles Cané (CNM, Barcelona), Ricardo Ibarra (INA, Zaragoza), Luis Hueso (Nanogune, San Sebastián), Albert Romano-Rodriguez (UB, Barcelona), Francesc Pérez-Murano (CNM, Barcelona), José Luis Prieto (UPM, Madrid), Santos Merino (Tekniker, Eibar), José Ignacio Martín (UNIOVI, Oviedo), José María De Teresa (ICMA, Zaragoza), Ricardo García (ICMM, Madrid).

The Local Committee of the 6th Spanish Workshop in Nanolithography is formed by José María De Teresa (Chairman), Ricardo Ibarra, Javier Sesé, Ana Isabel Gracia Lostao, Soraya Sangiao, Inés Serrano, Ismael Serrano, Laura Casado, Isabel Rivas, Teobaldo Torres, Rubén Valero, Mercedes Fatás, Susana Sangiao. The effort of Mercedes and Susana to the success of the event is especially acknowledged.

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The supporting institutions of the workshop are: Ministerio de Economía y Competitividad, Universidad de Zaragoza and CSIC.

The supporting companies of the workshop are: FEI (Special Supporter), Raith-Vistec (Special Supporter), Graphene Nanotech and ZEISS.

The scientific program is based on 51 contributions, split into 5 invited talks, 24 oral talks (including 5 oral talks in the industrial session) and 22 posters. We acknowledge our renowned invited speakers to have accepted to participate in the workshop: Prof. Albert Fert (U. Paris-Sud), Prof. Ivo Rangelow (Ilmenau University), Prof. Rainer Hillenbrand (Nanogune), Dr. Isabel Rodríguez (Imdea), Dr. Amalio Fernández-Pacheco (U. Cambridge). Besides, the workshop will host a Round Table entitled “Radiografía de la Investigación en España y Aragón” on 30th October. Additionally, the company Raith will organize a Raith User Meeting close to the workshop on 28th October.

You will find that Zaragoza is recognized to host visitors warmly. Hospitality in the city is an added value arising from its long history (20 centuries), characterized to be a meeting point of different cultures. Historical places such as the Roman theater and Roman walls, the Arab Aljafería castle, several Mudejar churches, a medieval bridge, etc. produce different sensations to the visitors. We are especially proud to host two cathedrals, an unusual fact, located in the impressive Plaza del Pilar, the heart of the city. Close to this place, the “Casco Viejo” is an unavoidable walking place, where you will meet impressive 19th century palaces, some of them hosting city museums such as the “Camón Aznar”, with several paintings from Goya, born in the province of Zaragoza. In the last years, Zaragoza made a move towards modernization, strongly fostered by the construction of the AVE railway infrastructures and by the organization of the EXPO exhibition in 2008. Several unique places from this recent period are the Delicias railway station, the “Pabellón-Puente”, the “Puente del Tercer Milenio” and the “Torre del Agua”. The University of Zaragoza, funded by the Aragón government and with additional support from the Spanish Ministry of Science and European funds, has made a strong bid in the field of Nanotechnology. In this context, it has the privilege to host the Laboratorio de Microscopías Avanzadas (LMA), the reference laboratory in Spain for advanced microscopies (http://ina.unizar.es/lma/). I hope that you will have the opportunity to visit this unique set of infrastructures and to discuss about collaborative projects with the local researchers. Best wishes for your stay in Zaragoza and your scientific exchanges during the workshop, José María De Teresa Chairman of the 6th Spanish Workshop in Nanolithography In the name of the Organizers (the Local Committee and the NANOLITO Scientific Committee)

EXHIBITORS

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Redefining the Boundaries of Conventional Materials Research

FEI’s Helios NanoLab™ 660 DualBeam™ characterizes samples at the nanoscale with the clearest contrast — even when they are beam sensitive or non-conductive — and delivers the fastest, most accurate milling and deposition for prototyping and sample preparation applications.

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Learn more at FEI.com/Helios-660

The technology-based company was created for manufacturing, research and Development in Epitaxial Graphene new materials in Nanoelectronics and Photonics, being located within the companies that can manufacture materials of the highest quality and technology in the market with focus Internalization, thus a Global level marketing and having a high degree R&D and Innovation.

We are in a growing market, being able to have an exponential growth and profits in the short / medium term time. Manufacturing products for groups of researchers from universities and technology centers, the industry also in the field of electronics and photonics for applications and medium-term sectors such as automotive industry, aeronautics, , Aerospace or military weapons may represent an important segment customers.

The products and services offered GRAPHENE NANOTECH are high quality and technology: -Epitaxial Graphene -Obleas SIC and characterized. -Graphene -Nanoribbons lithographed. -Consulting-service and support to our customers for incorporation of our products in their applications. The products are personalized to the needs of our customers.

The company works in collaboration with the National Microelectronics Centre Barcelona (CNM) the CSIC and the INA and ICMA members of the University of Zaragoza and CSIC.

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19 months after joining forces with Vistec Gaussian Beam Lithography, we are glad to introduce our new Corporate Design to the community. Both companies are now united under the Raith brand.

ZEISS is an international leader company in the fields of optics and optoelectronics, providing solutions for medical technology, research, industrial solutions and consumer optics. For more than 160 years, it has contributed to technological progress by offering innovative solutions. Today it is present in 40 countries, with more than 50 sales and service subsidiaries, and approximately 20 R&D centers around the world. As pioneer in optics science, ZEISS has been responsible for great innovations like the first compound microscope, the first aspherical optics or the first retrofocus for cinema. Today it is leader on its market. In 2013, its 24.000 employees worldwide generated revenues of 4.200 million Euros. The company also invested 411 million Euros in research and development.

In Spain and Portugal, ZEISS has three business units covering areas such as Medicine, Industrial Metrology, Microscopy, Planetary and Ophthalmic Lenses. Currently, the Microscopy division is one of the most prominent. Carl Zeiss Microscopy is one of the leading manufacturers of microscopes in the world. In addition to excellent light-/ion- and election microscopes, ZEISS also manufactures a diverse range of fluorescence optical sectioning systems as well as high-resolution x-ray microscopes. Overall, it is a leading provider of microscope solutions in the life sciences and materials research markets and QA/QC. In over 160 years of experience, the Microscopy division of ZEISS has presented solutions like the laser scanning microscope, an integrated widefield digital imaging system and the PlasDIC that allows the use of plastic dishes for microscopic examinations.

ORALS

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Invited talk

Scanning probe lithography (SPL) on molecular glass resists using self-actuating, self-sensing cantilever

Ivo W. Rangelow, Marcus Kaestner, Matthias Budden, Tzvetan Ivanov, Steve Lenk, Ahmad, Ahmad,

Yana Krivoshapkina, Tihomir Angelov, Elshad Guliyev, Alexander Reum, Manuel Hofer, Mathias Holz

Department of Micro- and Nanoelectronic Systems (MNES), Institute of Micro- and Nanoelectronics, Faculty of Electrical Engineering and Information Technology, Ilmenau University of Technology,

Gustav-Kirchhoff-Str. 1, 98693 Ilmenau, Germany

* [email protected]; phone +49 3677 69-3718; fax +49 3677 69-3132; http://www.tu-ilmenau.de/en/mne-mns/

Fabricating future devices in nanoelectronics, nanophotonics, and nanoelectromechanical systems requires lithography at the single-nanometer level with high alignment accuracy between patterns, acceptable throughput, cost, and reliability [1]. Durinl last years, we have shown the positive- or negativetone, development-less (or after development) patterning of calixarene molecular glass resists using highly confined electric field, current-controlled scanning probe lithography scheme. Here, we will give a detailed view insight describing the applied Scanning Probe Lithography (SPL) technology platform developed in our group applying self-actuating, self-sensing cantilever (Fig.1). The experimental results are supported by first preliminary simulation results estimating the local electric field strength, the electron trajectories, and the current density distribution at the sample surface. In addition, the diameter of Fowler-Nordheim electron beam, emitted from SPL-tip, was calculated as function of the bias voltage for different current set-points and tip radii. In experimental part we show the reproducible writing of patterns as well as the patterning of individual features using specially developed pattern generator software tool (Figure 2).

The research leading to these results has received funding from the European Union's Seventh Framework Programme FP7/2007-2013 under grant agreement no 318804 (Single Nanometer Manufacturing for beyond CMOS devices – acronym SNM). The authors thank Ch. Neuber from University of Bayreuth for PVD preparation of resist films, and M. Cooke from Oxford Instruments and J-F. de Marneffe from IMEC for carrying out the nano-pattern transfer investigation.

References [1] I. W. Rangelow, Tz. Ivanov, Y. Sarov, A. Schuh, A. Frank, H. Hartmann, J.-P. Z¨ ollner, D. Olynick, and V. Kalchenko, Nanoprobe maskless lithography, Proc. SPIE 7637, p. 76370V, 2010. doi:10.1117/12.852265 [2] Durrani, Z., Jones, M., Kaestner, M., Hofer, M., Guliyev, E., Ahmad, A., Ivanov, Tzv., Zoellner, J.-P., and Rangelow, I.W., “Scanning probe lithography approach for beyond CMOS devices,” Proc. SPIE – Int. Soc. Opt. Eng. 8680, 868017 (2013). [3] Kaestner, M., and Rangelow, I. W., “Scanning proximal probe lithography for sub-10 nm

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Fabrication of sub-12 nm thick silicon nanowires by processing scanning probe lithography masks

Yu Kyoung Ryu1, Pablo Aitor Postigo2, Fernando Garcia2 and Ricardo Garcia1

1Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain 2Instituto de Microelectrónica de Madrid (IMM-CNM-CSIC), 28760 Tres Cantos, Madrid, Spain

Silicon nanowires are key elements to fabricate very sensitive mechanical and electronic devices [1-3]. We provide a method to fabricate sub-12 nm silicon nanowires in thickness by combining oxidation scanning probe lithography and anisotropic dry etching [4]. Extremely thin oxide masks (0.3-1.1 nm) are transferred into nanowires of 2 to 12 nm in thickness (Fig 1). The width ratio between the mask and the silicon nanowire is close to one which implies that the nanowire width is controlled by the feature size of the nanolithography. This method enables the fabrication of very small silicon nanowires with cross-sections below 100 nm2. Those values are the smallest obtained with a top-down lithography method. We acknowledge support from the European Union under Grant Agreement No. 318804 (SNM). Figures

Figure 1. (a) Thickness of the resulting silicon nanowire as a function of the height of the initial oxide mask, (b) AFM topological images and cross sections of an array of oxide masks and the respective silicon nanowires produced after dry etching transfer.

References [1] R. V. Martinez, J. Martínez, and R. Garcia, Nanotechnology 21, 245301 (2010) [2] M. Chiesa, P. P. Cárdenas, F. Otón, J. Martínez, M. Mas-Torrent, F. García, J. C. Alonso, C. Rovira, and R. Garcia, Nano Lett. 12 1275(2012) [3] Y. K. Ryu, M. Chiesa, and R. Garcia, Nanotechnology, 24, 315205 (2013) [4] Y. K. Ryu, P. A. Postigo, F. Garcia, and R. Garcia, Applied Physics Letters, 104, 223112 (2014)

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E-beam assisted etching and patterning of few-layer molybdenum disulfide

Ramón Bernardo Gavito*1,2, Manuel Rodríguez Osorio2, Rodolfo Miranda1,2,3, Daniel Granados2

1Dpto. de Física de la Materia Condensada, Universidad Autónoma de Madrid, Facultad de ciencias, 28049, Madrid, Spain; 2IMDEA Nanociencia, Faraday 9, 28049, Madrid, Spain; 3Instituto de Ciencia de Materiales “Nicolás

Cabrera”, Universidad Autónoma de Madrid, Fac. Ciencias, 28049, Madrid, Spain; Ramó[email protected]

Transition metal dichalcogenides have attracted a huge interest since the isolation of graphene. This interest is based in the fact that these materials develop different properties when their thickness is reduced down to the monolayer or few-layer regime [1]. Among all of them, molybdenum disulfide (MoS2) is especially interesting because as a bulk it is a semiconductor with an indirect band-gap in the near-infrared region of the spectrum, and this band-gap blue-shifts when reducing the number of layers, resulting in a direct band-gap semiconductor which emits in the visible (1.85eV) when its thickness is reduced to a single layer [1, 2, 3].

During the last years, many different techniques for fabricating MoS2 single layers have been developed, such as mechanical exfoliation [2, 3], XeF2 plasma etching [4] and many others [5, 6].

In this work we use mechanical exfoliation to deposit MoS2 flakes on a SiO2/Si substrate and use an electron beam with a XeF2 flow to locally etch specific regions of the flake (Fig. 1) without using masks or electron beam lithography resists.

We also created point defects using a focused ion beam and visualized on-line the growth of hexagonal holes (Fig. 2) while using the SEM while keeping the XeF2 flow. This is consistent with the results obtained in [4] using a XeF2 plasma and graphene as a masking layer.

Using this method we are able to pattern the exfoliated MoS2 and to selectively etch the material with arbitrary shapes and a good lateral resolution. This will allow us to design complex structures with controlled thicknesses, giving us the possibility to fabricate different kinds of devices such as photonic crystals, quantum dots or transistors.

References [1] Qing Hua Wang, Kourosh Kalantar-Zadeh, Andras Kis, Jonathan N. Coleman, Michael S. Strano.

Nature Nanotechnology, 7, 699, (2012) [2] Kin Fai Mak, Changgu Lee, James Hone, Jie Shan, and Tony F. Heinz. Phys. Rev. Lett., 105, 136805,

(2010). [3] A Castellanos-Gomez, N Agraït, G Rubio-Bollinger. App. Phys. Lett., 96, 213116 (2010) [4] Yuan Huang, Jing Wu, Xiangfan Xu, Yuda Ho, Guangxin Ni, Qiang Zou, Gavin Kok Wai Koon, Weijie

Zhao, A. H. Castro Neto, Goki Eda, Chengmin Shen, and Barbaros Özyilmaz. Nano Research, 6, 200, (2013).

[5] Xiao Huang, Zhiyuan Zeng and Hua Zhang. Chem. Soc. Rev, 42, 1934, (2013) [6] Xin Lu, Muhammad Iqbal Bakti Utama, Jun Zhang, Yanyuan Zhao, Qihua Xiong. Nanoscale, 5, 8904

(2013). Figures

Figure 1. Cascaded MoS2 flake of different thicknesses patterned using the proposed technique used to calibrate the static-beam etching as a function of the flake thickness

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Deterministic transfer of two-dimensional materials to fabricate electronic and spintronic devices

Oihana Txoperena1*, Saül Vélez1, Luca Pietrobon1, Mário Alberto Oliveira1, Wenjing Yan1,

Luis E. Hueso1,2 and Fèlix Casanova1,2

1CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country

2IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Basque Country *[email protected]

The discovery of graphene, with its rich and fascinating properties [1], has opened up a new research area where two-dimensional (2D) materials are the platform to explore novel phenomena. Some of the properties that make graphene unique are the high mobility of charge carriers and their long spin relaxation times when travelling through this material. However, the absence of an energy band-gap on the band structure of pristine graphene is an issue for field-effect transistors (FET) [2], a property that other 2D materials such as transition metal dichalcogenides (TMD) fulfill due to their intrinsic band-gap [3]. MoS2, which belongs to the family of TMDs, has been recently demonstrated to exhibit giant spin-orbit-induced splitting and valley polarization [4], showing its potential to build spintronic- and valleytronic-based devices.

In this work we fabricate MoS2 FETs with mobilities as high as 100 cm2/(V·s) and on/off ratios in the order of 106. To fabricate the FETs, we mechanically exfoliate MoS2 and deterministically transfer flakes by using an all-dry viscoelastic stamping method [5] (see Figure 1). The electrical contacts to the MoS2 flakes are fabricated by electron-beam lithography and electron-beam evaporation of metals. The recently developed all-dry deterministic transfer method [5] allows us to fabricate and study the performance of FETs with both top and bottom contacts to MoS2 (Figure 1) and guarantees clean metal/flake interfaces. Once the electrical properties of MoS2 are well characterized, we plan to investigate its promising spin transport properties, which may overcome those of graphene.

References

[1] A. K. Geim & K. S. Novoselov, Nature Materials 6, 183 (2007); K. S. Novoselov et al., Nature 490, 192 (2012). [2] Q. H . Wang et al., Nature Nanotechnology 7, 699 (2012). [3] B. Radisavljevic et al., Nature Nanotechnology 6, 147 (2011). [4] Z. Y. Zhu, Y. C. Cheng, and U. Schwingenschlögl, Phys. Rev. B 84, 153402 (2011); K. F. Mak et al., Nature Nanotechnology 7, 494 (2012). [5] A. Castellanos-Gomez et al., 2D Mater. 1, 011002 (2014).

Figures

Figure 1: LEFT: Picture of the stamping setup at CIC nanoGUNE. RIGHT: Optical image of a top-contacted monolayer MoS2 FET.

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Invited talk Nanofabrication for Nanophotonics

Rainer Hillenbrand

CIC nanoGUNE, San Sebastian, Spain [email protected]

We discuss the application of electron beam lithography and focused ion beam machining for the fabrication of infrared antennas, among others for launching graphene plasmons (Figure 1) [1], infrared transmission lines (Figure 2) [2] and near-field probes (Figure 3) [3]. The functionality of the structures is verified by scattering-type scanning near-field optical microscopy (s-SNOM) and electron energy-loss spectroscopy (EELS), both techniques yielding plasmonic modes with nanoscale spatial resolution. References [1] P. Alonso-González et al., Science 344, 1369 (2014) [2] P. Sarriugarte et al., ACS Photon. (2014) [3] F. Huth et al., Nano Lett. 13, 1065 (2013) Figures

Figure 1: Launching graphene plasmons with a metal antenna. Left: Schematics of the s-SNOM experiment. Right: Topography of a gold nanoantenna on graphene (top) and near-field image showing the fields of the antenna and the graphene plasmons around the antenna (bottom). The near-field image was taken at an illumination wavelength of 11.06 μm and shows the real part of the imaged field. The distance between fringes of the same color reveals the graphene plasmon wavelength.

Figure 2: Infrared transmission lines. Left: Two SEM images of an infrared transmission line with 5 nm gap width, fabricated by Gallium and Helium ion beam milling. Right: Infrared near-field distribution (presented in color), plotted on top of the SEM image of the transmission line.

Figure 3: FIB fabricated near-field probes. Left: SEM image of a FIB fabricated Au tip on a commercial AFM cantilever. Middle: TEM image of a FIB fabricated Au tip. Right: EELS maps and spectrum of plasmonic antenna modes.

0

Inte

nsity

[a.

u.]

2

4

Energy loss [eV] 1 2 0.5 1.5 2.5

l=1

l=2

l=3

100 nm

Au

Si

0.75 eV 1.33 eV 1.8 eV

TEM EELS SEM

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Plasmonic nanostructured materials by bottom up self assembly of colloids

Hanbin ZHENG1,2, Rui M. Almeida2, Thomas RIVERA3, Serge RAVAINE1

1CNRS, Univ. Bordeaux, CRPP, UPR 8641, F-33600 Pessac, France

2Depart. Eng. Química/ICEMS, Instituto Superior Técnico/UL, Av. Rovisco Pais, 1049-001 Lisboa, Portugal 3Orange Labs, rue du Général Leclerc 92794 Issy Moulineaux, France

[email protected]

Bottom up self assembly processes to fabricate large scale ordered templates made of colloidal particles are viable alternatives to the costly top down approaches that are more commonly used in lithography. One simple way is to spread a suspension of polystyrene beads onto a water surface and pack them into a closed packed structure by tuning the surface tension of water with a surfactant [1]. The structural parameters of the template can be simply adjusted by choosing particles of the appropriate size and subsequently treating the templates under different conditions [2]. Electrodeposition can then be used to deposit metals into the monolayer colloidal templates that were prepared on conductive substrates [3], [4]. Here, we present an entire bottom up fabrication route that makes use of the self assembly of colloids and electrodeposition of metals to develop plasmonic materials with tunable properties. We demonstrate the relative ease of preparing a single monolayer of closed packed colloids on a substrate and the tunability of the pore size via a controlled sintering process. Furthermore, a plasma etching process can also be used to create non closed packed colloidal templates. By depositing the colloidal templates on conductive substrates, we show that the template prepared by self assembly can be readily used for electrodeposition of different metals to create (1) 2D arrays of gold nanoantennas with tunable geometries and (2) macroporous gold surfaces that exhibit omnidirectional total light absorption properties. References [1] N. Vogel, S. Goerres, K. Landfester, and C. K. Weiss, Macromol. Chem. Phys., vol. 212, no. 16, pp. 1719–

1734, Aug. 2011. [2] H. Cong, B. Yu, J. Tang, Z. Li, and X. Liu, Chem. Soc. Rev., vol. 42, no. 19, pp. 7774–800, Oct. 2013. [3] M. Heim, S. Reculusa, S. Ravaine, and A. Kuhn, Adv. Funct. Mater., vol. 22, no. 3, pp. 538–545, Feb. 2012. [4] H. Zheng, R. Vallée, R. M. Almeida, T. Rivera, and S. Ravaine, Opt. Mater. Express, vol. 4, no. 6, p. 1236,

May 2014.

Figures

Figure 1. SEM pictures of gold nanoantenna arrays with different geometries.

Figure 2. SEM pictures of a macroporous gold surface

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Plasmonic hollow cylindrical nanostructures fabricated by Nanoimprint Lithography and non-directional metallization

A. Conde1, M. Kovylina1, N. Alayo2, X. Borrisé2, F. Pérez-Murano2, G. D. Hibbard3, X. Batlle1 and A.

Labarta1

1D. Física Fonamental, Universitat de Barcelona and Institut de Nanociència i Nanotecnologia, Martí i Franquès 1, 08028 Barcelona, Spain

2Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC) UAB, 08193 Bellaterra, Barcelona, Spain 3D. Materials Science and Engineering, University of Toronto, 184 College Street, M5S 3E4, Toronto, Canada

[email protected]

A high-throughput, low cost process for the fabrication of hollow cylindrical nanoparticles with a precise control of their geometry and variable composition has been developed. The process is based on combining concepts from stencil and nanoimprint lithography (NIL), together with the use of non-directional metallization by means of sputtering. It allows the realization of large arrays of nanoparticles with accurate positioning control. The process starts by imprinting a trilayer structure consisting on a bottom layer of poly(methyl methacrylate) (PMMA) 950k MW, an intermediate thin layer of SiO2 and a top layer of PMMA 75k MW, which are deposited on a Si or glass substrate. Then, the top layer is patterned by NIL using Si dotted stamps. Afterwards, a dry reactive ion etching process is carried out to transfer the pattern to the bottom PMMA layer. In this way, an optimal undercut is obtained for the final lift-off process. Metal deposition is performed by RF magnetron sputtering, allowing the combination of different materials and the obtention of bifunctional nanoparticles. Two different compositions have been successfully obtained: Au and AuFe hollow cylindrical nanostructures with 400 to 500 nm diameter and heights in the range of 300 to 500 nm (see Figure 1). The unique properties of Au such as its chemical stability, biocompatibility and easy functionalization as well as its surface plasmon resonance (SPR) [1] which entails effects such as absorption and scattering enhancement or concentration of the electromagnetic field [2], make it the perfect candidate for applications in areas such as photovoltaics [3], sensing [1][2], and medicine [4]. SPR is highly dependent on the size, shape, inter-particle spacing, orientation, local dielectric medium and composition, therefore the method should allow the fabrication of nanostructures with controlled geometry and homogeneous distribution on the substrate [2]. Besides, finite difference time domain simulations of Au hollow cylindrical nanostructures with a diameter of 400 nm, 400 nm high and a wall thickness of 30 nm demonstrate a great enhancement of the electromagnetic field, which is promising for fabricating functional devices based on surface raman enhanced spectroscopy (SERS).

This work was supported by Spanish MINECO (MAT2012-33037), Catalan DURSI (2009SGR856, 2014SGR220), and European Union FEDER funds (Una manera de hacer Europa). A. Conde acknowledges Spanish MINECO for a Ph.D. contract (BES-2013-065377). References [1] B. Sepúlveda, P. C. Angelomé, L. M. Lechuga, and L. M. Liz-Marzán, Nano Today 3, 244, (2009) [2] G. a Baker and D. S. Moore, Anal. Bioanal. Chem. 8, 1751 (2005) [3] M. Losurdo, et al, Sol. Energy Mater. Sol. Cells 10, 1749 (2009) [4] L. A. Dykman and N. G. Khlebtsov, Acta Naturae 9, 34 (2011)

Figure 1: AuFe hollow cylindrical nanostructures on a Si substrate.

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Gold/Polymer nanogratings fabricated by Nanoimprint Lithography for application as Surface Enhanced Raman Scattering sensors

T.A. Ezquerra1 , M. Soccio2, M. Hernández1, M.C. García-Gutiérrez1, C. Domingo1,

N. Alayo3, F. Pérez-Murano3, E. Rebollar4, M. Sanz4, M. Castillejo4

1Instituto de Estructura de la Materia, IEM-CSIC. C/ Serrano 121, Madrid 28006, Spain.

2Dipartamento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Universitá di Bologna, Via Terracini 28, Bologna 40131, Italy.

3Instituto de Microelectrónica de Barcelona-Centro Nacional de Microelectrónica, IMB-CNM-CSIC Campus UAB 08193, Cerdanyola del Vallès (Bellaterra) Barcelona, Spain. 4Instituto de Química Física Rocasolano, IQFR-CSIC, C/Serrano 119, Madrid 28006, Spain

[email protected]

Polymers coated with metallic nanoparticles are materials with a large scientific and technological interest. Such a gold-polymer hybrid systems may benefit from the excellent mechanical flexibility, light weight, enhanced durability and low cost of the polymer substrates in comparison with more rigid substrates and from the inherent properties of nanostructured metals. It is known that surface plasmons induced by an electromagnetic field in metallic nanostructures significantly increase the Raman signal leading to a high sensitivity spectroscopic technique referred to as Surface-Enhanced Raman Scattering (SERS) [1] of potential interest for sensing[2]. Here we report on the fabrication of hybrid systems consisting on Nanoimprint Lithographied polymer nanostructures subsequently coated with gold by Pulsed Laser Deposition (PLD). Highly ordered gratings and dots, nanofabricated on polymer films by Nanoimprint Lithography (NIL) can be produced (Fig.1a). Either silicon gratings, prepared by electron beam lithography or anodic aluminum oxide (AAO) membranes were used as stamps to imprint spin-coated polymeric thin films using a thermal nanoimprint system. The capabilities of these nanostructures as substrates for SERS have been investigated using benzenethiol (BT) as a test molecule. As an example, Fig.1b shows the Raman spectrum of a drop of BT diluted to a concentration of 10-4M and dried in air on a gold coated flat polymer film and on a gold coated polymer grating. In the case of BT poured on the spin-coated polymer surface, no Raman signal of BT is observed. However, the spectrum acquired on the gold coated polymer grating clearly displays the BT characteristic bands. The capabilities of these nanostructures for SERS sensing will be discussed. References [1] R. Aroca, Surface enhanced vibrational spectroscopy, Wiley, Hoboken, NJ, 2006. [2] E. Rebollar, M. Sanz, S. Pérez, M. Hernández, I. Martín-Fabiani, D.R. Rueda, T.A. Ezquerra, C. Domingo, M. Castillejo, Phys. Chem. Chem. Phys., 14 15699 (2012).

Figure 1: (a) Gold coated polymer grating. (b) Raman spectrum of a drop of BT diluted to a concentration of 10-3M and dried in air on a gold

coated polymer film and on a gold coated polymer grating nanofabricated by NIL.

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Label-Free Biosensor based on Localized Surface Plasmon Resonance with custom microfluidic solution for TNF detection

D. Otaduy1,2, J. Martínez-Perdiguero2, A. Retolaza1,2, A. Juarros1,2, and S. Merino1,2. 1IK4-Tekniker, Micro and Nano Manufabrication, Eibar 20600, Spain.

2 CIC microGUNE, Goiru Kalea 9 Polo Innovación Garaia, 20500 Arrasate-Mondragón, Spain

[email protected]

Surface plasmon resonance (SPR) sensors are a common tool for real-time label-free biosensing because of their ease of use and good performance. The Kretschmann configuration [1] is the most used commercial SPR systems requiring a somehow complex non-collinear optical set-up. The use of enhanced transmission through metallic sub-wavelength nanohole arrays [2] to couple the incoming light to surface polaritons has proven to be a very good alternative because of its simple linear set-up and boasts higher spatial resolution [4], making it feasible for the miniaturization of the sensing device.

In previous work [2] the fabrication process by Nanoimprint Lithography (NIL), suitable for mass-production, was optimized and the arrays were fully characterized. It was also proved to be repetitive and the quality of the arrays similar to those manufactured using fabricated by Focused Ion Beam (FIB) [3, 4], or Electron Beam Lithography (EBL) [5]. Moreover, the biosensing capabilities of the fabricated arrays were demonstrated monitoring in real-time the absorption of bovine serum albumina (BSA) protein onto the gold surface without the necessity of labels.

In this work the nanostructure geometry has been optimized to get a sensibility up to 348nm/RIU and the optical set-up has been improved by the design and fabrication of a customized microfluidic cell (figure 1a), which provides the system with two major advantages: increases the biosensor reliability (robustness and reproducibility); and it allows an easy change and correct positioning of the low-cost disposable chips.

In addition, this biosensor has been proved feasible to be used for the detection of TNFα protein biomarkers. Spiked buffer samples with different concentration of TNFα have been measured (figure 1b) getting a limit of detection (LOD) about 100ng/ml. In future works signal amplification will be studied by adding gold nanoparticles, so that, lowering the LOD.

References

[1] E. C. Nice and B. Catimel, “Instrumental biosensors: new perspectives for the analysis of biomolecular interactions” BioEssays. vol. 21, no. 4, pp. 339–52, Apr. (1999).

[2] J. Martínez Perdiguero, A. Retolaza, D. Otaduy, A. Juarros, S. Merino. “Real-time label-free surface plasmon resonance biosensing with gold nanohole arrays fabricated by NIL”. Sensors, vol. 13 (2013)

[3] T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, and P. A. Wolff, “Extraordinary optical transmission through sub-wavelength hole arrays,” Nature, vol. 391, pp. 667–669, Feb. (1998).

[4] A. Lesuffleur, H. Im, N. C. Lindquist, and S.-H. Oh, “Periodic nanohole arrays with shape-enhanced plasmon resonance as real-time biosensors,” Applied Physics Letters, vol. 90, no. 24, p. 243110.. (2007)

[5] J. C. Sharpe, J. S. Mitchell, L. Lin, N. Sedoglavich, and R. J. Blaikie, “Gold nanohole array substrates as immunobiosensors.,” Analytical chemistry, vol. 80, no. 6, pp. 2244–9. (2008)

Figure 1

Figure 1: a) Customized microfluidic cell for low-cost disposable chips. b) A clear red shift with increasing concentration (or n value) can be

observed, PBS with no TNF (blue), 1g/ml TNF in PBS (green) and 50g/ml TNF in PBS (red)

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Invited talk

Probing three-dimensional spintronic nanostructures Amalio Fernández-Pacheco

1Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, UK, CB3 0HE

[email protected]

Spintronic devices, exploiting the intrinsic magnetism of electrons, are an alternative to CMOS technology, combining non-volatility with high-speed operation. Moreover, it would be a real breakthrough if new spintronic systems where data was stored and processed along all three dimensions were created. In this talk I will present some of the work I have performed during the last years towards this objective, where two types of three-dimensional spintronic nanostructures have been investigated.

The first system consists of magnetic nanowires grown by focused electron beam induced deposition (FEBID) using Co2(CO)8 as gas precursor. FEBID is a nanolithography technique with a unique performance to pattern complex high aspect-ratio 3D nanowires (fig. 1), with a great potential to form vertical racetrack memories [1]. Using Kerr magnetometry (MOKE), micromanipulation and probe microscopy techniques, I will show how the switching of 3D nanostructures can be measured and the mechanism behind it determined [2].

The second system is based on superlattices formed by alternating magnetic/non-magnetic films coupled antiferro-magnetically (AF) via RKKY interactions. In this case, AF-walls can be injected and vertically propagated into the system [3]. The combination of bulk and focused magnetometry, magnetoresistance (MR) measurements, polarised neutron reflectivity (PNR) and simulations makes possible to study the evolution of these systems under different conditions (fig. 2). Moreover, by tuning in an alternating way the anisotropy of the layers and the coupling between them a ratchet profile for wall propagation is created, which can be exploited to form 3D magnetic shift registers [4]. The different magnetisation reversal mechanisms of individual layers whilst vertically shifting bits [5] will be also presented. References [1] S. S. P. Parkin et al, Science 320, 190 (2008). [2] A. Fernández-Pacheco et al, Sci. Rep. 3, 1492 (2013). [3] A. Fernández-Pacheco et al, Phys. Rev. B 86, 104422 (2012). [4] R. Lavrijsen et al, Nature 493, 647 (2013); Nanotechnology 25, 105201 (2014). [5] J-H. Lee et al, Appl. Phys. Lett. 104, 232404 (2014); SPIN 3, 1340013 (2014). Figures

Figure 1: 3D Cobalt nanowires grown by FEBID. (a) SEM image of a nanowire forming 45o with the substrate (b) MOKE loop of this wire.

Figure 2: AF-walls in superlattices. (a) MR signal of a 4-layer CoFeB/Ru system. (b) PNR corresponding to the state marked with an asterisk in (a), associated to injection and partial propagation of an AF-wall into the system.

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Electron beam induced deposition of high-purity and high-aspect-ratio three-

dimensional cobalt structures

Luis Serrano-Ramón1, A. Fernández-Pacheco2, L.A. Rodríguez1,3,4, C. Magén3,4,5, C. Gatel1, E. Snoeck1, M. R. Ibarra3,4 , J. M. de Teresa3. 4, 6.

1 CEMES-CNRS 29, rue Jeanne Marvig B.P. 94347 F-31055 Toulouse Cedex, France.

2 TFM Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK. 3 Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009, Zaragoza, Spain.

4 Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, Campus Río Ebro, E-50018, Zaragoza, Spain.

5 Fundación ARAID, E-50018, Zaragoza, Spain. 6 Instituto de Ciencia de Materiales de Aragón, Facultad de Ciencias, Universidad de Zaragoza-CSIC, E-50009, Zaragoza, Spain.

[email protected]

While classical lithography techniques struggle to deposit 3D structures, the versatility of FEBID growth process makes this technique one of the best suited for the growth of these structures. However, even though planar cobalt nanostructures have been mastered by FEBID, achieving a lateral resolution below 30 nm [1, 2], the lack of reproducibility and resolution below the 100 nm range in functional 3D samples prevent these novel structures from becoming more extended. In this work we have studied the deposition of complex 3D cobalt nanostructures of high aspect ratio (diameter of 80 nm), high purity over 90% at. and no texture, presented in previous works [3]. We have used a pulsed deposition strategy to minimize thermal effects and investigated the role of the precursor flux, refresh time and dwell time in the growth process. An appropriate tuning of the precursor flux in combination with the use of low beam currents in the pA range leads to high purity deposits (Fig. 1a), as observed in the EDX experiments. The microstructure of the pillars, measured by TEM, resembles that of the planar nanowires [4], which have proved to show a good domain wall conduit behavior [5]. Electron holography measurements prove the ferromagnetic nature of the nanowires and show a magnetization saturation value of 0.7 T (Fig. 1b). Further work is necessary to improve these properties and test its domain wall conduit behavior. Nevertheless, this work paves the way towards the implementation of cobalt nanostructures deposited by FEBID in new three-dimensional data storage and processing devices. References [1] Serrano-Ramon, L., Córdoba R,, Rodríguez L. A., Magén C., Snoeck E., Gatel C., Serrano I., Ibarra M. R., and De Teresa J. . ACS Nano, 5(10), 7781-7 (2011). [2] Nikulina E, Idigoras O, Vavasori P, Chuvilin A and Berger A, Appl. Phys. Lett. 100,142401 (2012). [3] Fernández-Pacheco, A., et al. Sci Rep, 3. 1492 (2013). [4] Córdoba R, Fernández-Pacheco R, Fernández-Pacheco A, Gloter A, Magen C, Stephan O, Ibarra M R and De Teresa J. M.,Nanoscale Res. Lett. 6, 592 (2011). [5] Fernández-Pacheco A, De Teresa J M, Córdoba R, Ibarra M R, Petit D, Read L, O’Brien D E, Lewis E R, Zeng H T and Cowburn R. P., Appl. Phys. Lett. 94, 192509 (2009).

Figure 1: a) EDX measurements of the pillars as a function of the precursor flux used during the deposition. b) Induction modulated electron holography image. The colors denote the direction of the magnetic flux and the density of the lines is related with the magnitude of the magnetic induction in the image.

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Magnetotransport in Nanopatterned La2/3Ca1/3MnO3 Nanowires

Lorena Marín,†,‡,§ Luis Morellón,*,†,‡ Pedro A. Algarabel,‡,§ Luis A. Rodríguez,†,‡ César Magén,†,‡,∥

JoséM. De Teresa,†,‡,§ and Manuel R. Ibarra†,‡

†Laboratorio de Microscopıás Avanzadas (LMA) - Instituto de Nanociencia de Aragoń (INA),

Universidad de Zaragoza, 50018 Zaragoza, Spain ‡Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza,

Spain §Instituto de Ciencia de Materiales de Aragón (ICMA), Universidad de Zaragoza-CSIC, 50009

Zaragoza, Spain ∥Fundación ARAID, 50018 Zaragoza, Spain

[email protected]

Micro- and nanowires were patterned from epitaxial La2/3Ca1/3MnO3 (LCMO) thin films deposited on (001)-oriented SrTiO3 (STO) substrates of 1/2 × 1/2 in. by pulsed laser deposition (PLD). We have combined optical and focused ion beam lithographies to produce large aspect-ratio (length-to-width >300) single-crystal nanowires of LCMO that preserve their functional properties. We have found the resistivity and the metal−insulator transition temperature TMI to strongly depend on the width of the wires. Remarkably, an enhanced magnetoresistance value of 34% in an applied magnetic field of 0.1 T in the narrowest 150 nm nanowire is obtained. The strain release at the edges together with a destabilization of the insulating regions is proposed to account for this behavior [1]. References [1] L. Marin, et al, Nano Letters, 423-428 (2014) Figures

Figure 1: Magnetoresistance at T = TMI as a function of magnetic field for different wire width. Insets show a schematic

representation of the nanolithography process and a SEM image of the micro and nanowire.

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Electromechanical transduction in silicon nanowire mechanical resonators fabricated by focused ion beam (FIB) implantation

Jordi Llobet1, Marc Sansa1,*, Xavier Borrisé2 and Francesc Pérez-Murano1

1Institut de Microelectrònica de Barcelona (IMB-CNM CSIC), Campus UAB 08193, Barcelona (Spain)

2Institut Català de Nanociència i Nanotecnologia (ICN2), Campus UAB 08193, Barcelona (Spain) *Currently at CEA-LETI / MINATEC, Grenoble (France)

Presenter’s e-mail address: [email protected] We present the fabrication of silicon nanowire (SiNW) mechanical resonators by a resistless process based on focused ion beam local gallium implantation, selective silicon etching and diffusive boron doping. The resulting suspended SiNWs present a good electrical conductivity which is employed to characterize their high frequency mechanical response by electrical methods. The fabrication of suspended silicon nanowires (Fig. 1) by this method is simple, fast and reliable, and it does not require a critical surface preparation, since it proceeds correctly even in the presence of silicon native oxide [1]. The etching of the underlying Si is performed by wet silicon etching using TMAH (tetramethilammonium hydroxide) at 25% of concentration. We take advantage of the anisotropic etching rate of TMAH to obtain released or non-released nanowires according to their specific orientation. The last step consists on a post-annealing at high temperature in a boron environment, allowing the recovering of the crystalline structure and the improvement of the electrical conductivity of the silicon nanowire [2]. The final resistivity of the SiNWs is on the order of 10-4 Ω·m The devices consist on double clamped SiNWs with a side-gate nearby for electrostatic actuation. A SEM image of one of the fabricated device is shown in Fig. 2a. The length of the nanowire is 4.14 µm and the dimensions of the cross-sectional area are 40 nm (thickness) x 540 nm (width). The thickness of the SiNW is 40 nm that corresponds to the range of implanted gallium. As the suspended SiNWs are conductive at the end of the fabrication process, the electrical read-out of their mechanical oscillation is enabled. We measure their frequency response by using a frequency modulation (FM) electrical down-mixing method (Fig 2.b) [3,4]. The measurements are performed inside the vacuum chamber of the SEM/FIB system using three micromanipulators with electrical connection for low-resistance and low-noise electrical measurements. We have been able to identify the different resonant modes of the devices. The flexibility of the technique allows to experiment in different designs like coupled devices or asymmetric structures.

Acknowledgements: This work was partially funded by the project SNM (FP7-ICT-2011-8)

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Integration of Molecular Magnets, Biomolecules and Nanoparticles on Devices

María Carmen Pallarés 1, Anabel Lostao 1, 2

1Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, 50018

Zaragoza, Spain. 2Fundación ARAID, Spain [email protected]

Dip-Pen Nanolithography (DPN) uses an implemented Atomic Force Microscope (AFM) to create nanoscale patterns on material surfaces. The tip of a DPN probe is coated with an “ink” and traced across a target surface. As the probe traverses the surface, the ink is deposited along the drawing path and diffuses away from the tip. By varying the tip speed, dwell time, humidity and temperature it is possible to create lines of various widths or dots of various radius, and lines and dots can be combined to create complex patterns with heights ranging from nanometers to microns. DPN works with a wide variety of inks —such as DNA, proteins and organic molecules— and can create patterns on many different types of materials, including silicon, metals, and glass. It can also work with single or multi-pen probe arrays and microfluidic systems for wetting small amounts of inks. As a result, DPN can be used as a nanofabrication platform to create a diverse set of products such as nanoscale electronic circuits, nanoarrays of organic materials, and physical, biological or chemical sensors. This communication will show different results with the first DPN5000 system (NanoInk, Inc., USA) installed in Spain obtained by our group. We have positioned different nanomaterials on different substrates covering from less than 100 nanometers till several hundred of microns and heights varying from sub-monolayers till a few microns. Among them we have organized mono and bi-layers of molecular magnets on 25 m in-diameter rings and circles on the most sensitive regions of micro-SQUID superconductor devices. We have filled arrays composed of small wells of barely 1,5 microns in-diameter and 50 nm depth with organic molecules. Small thiolated proteins were strongly immobilized forming arrays on gold for different purposes. Remarkably, our group was the first achieving the direct deposition of controlled amounts of different metallic nanoparticles on micromechanical devices. Figures

Figure 1: 3D representation of an AFM image of a protein array composed by 1 micron dots of about 10 nanometers in height deposited by DPN on gold.

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Invited talk Topographical and chemical patterning of functional surfaces

Isabel Rodríguez1, 2

1 Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanoscience), C/Faraday 9, Ciudad

Universitaria de Cantoblanco, Madrid 28049, Spain. 2Institute of Materials Research & Engineering, A*STAR (Agency for Science, Technology and Research),

3 Research Link, Singapore 117602 [email protected]

Many different species in nature have adapted to their habitats by exploiting special surface functionalities. For example the water-walking ability of water striders, the bright colors of butterfly wings, the ability to walk up the walls by geckoes, the self-cleaning ability of shark skin, the ability to stay dry and collect water by the lotus or the cactus leaf. All these surface functions are achieved by unique skin textures in combination with the inherent materials properties. Indeed, without changing the chemical composition, the surface topography can influence the material properties and as a result, the interaction with or response to such material. Wetting, friction or adhesion properties of a specific surface can be altered depending on the specific topographical features present on that surface. For instance, the topography of a surface can be designed to confer diverging properties such as anisotropic wetting, super hydrophobic or super hydrophilic, adhesive or antifouling. Micro and nanofabrication technology offer to us the opportunity to mimic natural surfaces and impart additional properties or functions to artificial materials. However, the processes are not always straightforward as these natural textures involve convoluted hierarchical structures in the micro and nano scale. Among the technologies, polymer nanoimprinting is one of the most suitable techniques for this pursuit due to the process resolution and versatility. In this talk, the specific nanoimprinting processes and surface functions created would be described ranging from gecko inspired dry adhesives [1], superhydrophobic surfaces mimicking the lotus leave effect [2] to surfaces with increased physiological biocompatibility [3]. Micro and nanofabrication techniques also offer the possibility to construct tools to effectively manipulate and analyze biological entities such cells in a control fluidic environment. In the second part of the presentation, application of micro/nano technology to construct protein micro patters and cell arrays will be illustrated [4]. References [1] Ho, AYY; Yeo, LP; Lam, YC, Rodriguez I., ACS Nano 3, 1897-1906 (2011) [2] Ho, AYY; Luong van E; Lim, C; Natarajan; S, Elmouelhi, N ; Low, HY; Vyakarnam, M ; Cooper, K; Rodriguez, I., J Pol Sci: Pol Phys 52, 603-609 (2014) [3] Li Buay Koh , Isabel Rodriguez , Subbu S. Venkatraman. Biomaterials 7, 1533-1545 ( 2010) [4] Lin, LY; Chu, YS; Thiery, JP; Lim, CT; Rodriguez, I., Lab Chip 4, 714-721( 2013) Figures

Figure 1: Biomimetic gecko toe structure and lotus like surface fabricated by nanoimprinting in polymer.

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Directed self-assembly of block copolymers by chemical surface modification

Laura Evangelio1,2, Marta Fernández-Regúlez1, Jordi Fraxedas2, Francesc Pérez-Murano1

1Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), UAB, Bellaterra (08193), Barcelona, Spain

2Institut Català de Nanociència i Nanotecnologia (ICN2), UAB, Bellaterra (08193), Barcelona, Spain

[email protected]

The miniaturization trend in many areas of science and technology is demanding the continuous resolution improvement of patterning methods. Therefore, convenient ways of scaling with resolution below 10 nm should be developed. Although technically possible, the extension of optical lithography to even smaller dimensions suffers from rapidly increasing costs. Directed self-assembly (DSA) of block copolymers (BCP) is becoming a well-established and attractive patterning method because it allows patterning surfaces at high resolution and throughput [1]. BCPs are macromolecules formed by two (or more) chemically distinct polymer chains joined by inter-block covalent bonds, and they possess the intrinsic property of self-assemble and form dense arrays of nanostructures at length scales that are very difficult or impossible to create using conventional lithographic materials and processes [2]. Nevertheless, it is important to highlight that the DSA of BCP is not intended to replace traditional lithography, but offer a complementary alternative for use, since it combines the intrinsic property of these materials to self-assemble with the use of lithographic tools to create patterns that guide the assembly of BCP domains into desired structures [3]. Highly oriented periodic patterns can be achieved by pre-patterning the substrate surface with chemical functionality (chemical epitaxy) or a surface topography (graphoepitaxy).

We present the progress on directing the self-assembly of PS-b-PMMA by chemical surface modification using two different approaches, with density multiplication factors up to 7. In one approach (Figure 1.a), the guiding patterns are created by e-beam lithography (EBL) followed by an O2 plasma. In a second approach (Figure 1.b), these patterns are created by employing atomic force microscopy (AFM) based nanolithography. The main advantages of AFM nanolithography are the higher resolution and control in the definition of the guiding patterns, and the simplification of the overall process since the pattern is directly created on the neutral surface without the need of a resist.

The research leading to these results has received funding from the European projects SNM (FP7-ICT-2011-8), CoLiSa (FP7-ICT-2013-11) and PLACYD (ENIAC-621277)

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Tailoring of nanostructure in thin films through control of self-assembled block-copolymers morphology by small molecules hosting.

F. Valdés-Bango1,2,*, A.Álvarez3, F. J. García-Alonso1,3, M. Vélez2, J. I. Martín1,2,

J. M. Alameda1,2

1CINN (CSIC - Universidad de Oviedo - Principado de Asturias), Llanera, Asturias, Spain

2Depto. Física, Universidad de Oviedo, 33007 Oviedo, Spain 3Depto. Química Orgánica e Inorgánica, Universidad de Oviedo, 33006 Oviedo, Spain

[email protected]

Recently block-copolymers have become an important field of interest due to their self-assembled microdomains distribution on surfaces and therefore their capability to reproduce structure patterns of materials over great areas [1].Original studies from simple forms have evolved through complementation with other lithographic techniques to achieve more complex and oriented patterns. Their promising applications cover a wide area range from electronic [2] and magnetic circuits, media recording [3,4], energy efficiency, optics or biomedical [5] among others. Precise control of size, morphology and pattern homogeneity is a key milestone to achieve before its application, consequently in this work we have studied the role of guest molecules in block-copolymer polystyrene – poly 4 vinylpyridine (PS-P4VP) leading to a versatile method to obtain a large variety of structures by spin coating processes on Si substrates (see Figure 1). We have obtained micelles, vertical cylinders, and complex nanorings and nanomushrooms, whose sizes and interdistances we are able to tailor in ranges of 30-110 nm of diameter by tuning their chemical properties (with the inclusion of different host molecules in the P4VP cores) and physical properties during spin coating. Furthermore, we have also studied the reproducibility of the configurations in a variety of substrates with different chemical nature, obtaining similar behavior in all samples. Finally, we have also analyzed the possibility to obtain magnetic nanoparticles by incorporation of magnetic salts with affinity for P4VP domains. References [1] Julie.L.Albert et al, Materials Today 13 6, 24-33(2010). [2]D.O.Shin, J.H.Mun et al, ACS Nano 7 10, 8899-8907 (2013). [3]R.Ruiz, E.Dobisz et al, ACS Nano 5 1, 79-84 (2011). [4] W. I. Park et al, ACS Nano 7 3, 2651-2658 (2013) [5] C. K Jeonget al, Small 10 2, 213. (2014)

Acknowledgedments:

Work supported by Spanish MINECO under grant FIS2008-06249 and FIS2013-45469

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Top-Down approach for Water Dispersible Threee-Dimensional LC-Nanoresonators

Vito Clericò1, L.Masini2, A.Boni3, S.Meucci2, M.Cecchini2, F.Recchia4, A.Tredicucci2, A. Bifone3

1Sala Blanca de Nanotecnología, Universidad de Salamanca, Edificio I+D+I Calle Espejo, 37007 Salamanca, Spain

[email protected] 2NEST, CNR-Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, I-56127 Pisa,

Italy 3Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12,

56127 Pisa, Italy 4Institute of Life Sciences, Scuola Superiore Sant’Anna, Piazza Martiri della Libertà 33, 56127 Pisa, Italy

Chemical synthesis is an established technique to produce metal nanoparticles whose surfaces can be functionalized to obtain stable dispersions in liquids, and to selectively detect molecular interactions [1]. This bottom-up approach, however, presents some important limitations. Firstly, the optical properties of these nanoparticles are determined by the intrinsic characteristics of the material they are made of, and can be tuned within a very limited range of resonance frequencies [2]. Moreover, the repertoire of structures that can be obtained by chemical synthesis is limited, thus constraining the possibility to tailor and fine-tune their properties by changing shape and size. Alternatively, top-down nanofabrication approaches offer great control of these last two parameters and enables the fabrication of complex nanodevices that can be used for biosensing purposes. However, this devices are normally supported by a substrate and their use is limited to in vitro applications [3]. There are only few works [4][5] on nanostructures made with a top-down approach and dispersed in liquid environment. Following a top-down procedure, we designed and fabricated composite inductance-capacitance (LC) nanoresonators that can be detached from their substrate and dispersed in water. The multimaterial composition of these resonators makes it possible to differentially functionalize different parts of the device to obtain stable aqueous suspensions and multi-sensing capabilities. For the first time, we demonstrate detection of these devices in an aqueous environment, and we show that they can be sensitized to their local environment and to chemical binding of specific molecular moieties. The possibility to optically probe the nanoresonator resonance in liquid dispersions paves the way to a variety of new applications, including injection into living organisms for in vivo sensing and imaging. References [1] AJ Haes et al., J Am Chem Soc 124:10596-10604 (2012) [2] K Kelly et al., J Phys Chem B 107:668-677 (2003) [3] A Cattoni et al., Nano Lett 11: 3557-3563 (2011) [4] W Hasan et al., Nano Lett 9: 1555-1558 (2009) [5] AG Mark et al, Nature Materials 12: 802-807 (2013) Figures

Figure 1: SEM-Images of the nanoresonators disposed in array (a) and pulled off the substrate and randomly oriented (b). (c) Simulations with Comsol 4.2: z-component of the electric and norm of the magnetic fields(colour plot) demostrate the LC-behaviour. The arrows represent the direction and the sign of the electric and magnetic field.

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Nanostructuration as a way to induce a vortex smectic phase in Nb thin films

J. del Valle1, A. Gómez1, F. Gálvez1, M. Rodríguez2, D. Granados2, E.M. González1,2 and J.L. Vicent1,2

1Departamento de Física de Materiales, Facultad CC. Físicas, Universidad

Complutense, 28040 Madrid, Spain

2IMDEA-Nanociencia, Cantoblanco, 28049 Madrid, Spain

[email protected] In recent years, a lot of attention has been paid to nanostructured superconductors. Adding an artificial pinning landscape, using nanolithography techniques, has allowed to observe a broad range of new phenomena such as matching effects, ratchet of vortices or guided motion1. Most of this research however, is focus in the dynamic regime, when vortices are in motion, and much less attention has been given to the study of how nanostructuring in the superconductor may alter the different vortex phases typically present in the mixed state 2. Vortex matter is known to show a great variety of phases, such as vortex liquids, Bose glasses, Bragg glasses or smectic phases3,4, most of them only observed in high Tc superconductors. In this work we show evidence of an artificially induced vortex smectic phase by means of artificial nanostructured pinning centers embedded in Nb thin films. The pinning centers consisted on rectangular arrays of Cu dots (100 nm radius), fabricated using EBL and magnetron sputtering techniques. Afterwards, a superconducting Nb thin film was sputtered on top. Later, optical lithography and reactive ion etching process allow us to define an electrical transport measurement bridge. We studied the transport properties of the system very close to Tc at several magnetic fields. The I-V characteristics show a crossover that takes place at different temperatures depending on the direction of the current, signaling an anisotropic freezing that is incompatible with a liquid to vortex glass transition. The resistivity critical exponents found at the transition are in the expected range of a vortex liquid to smectic transition, indicating that we have induced a smectic phase in the system by means of anisotropic pinning potentials. References [1] A. Gómez, D.A. Hilbert, E.M. González, K. Liu and J.L. Vicent, Appl. Phys. Lett. 102, 052601 (2013)

[2] J. E. Villegas, E. M. Gonzalez, Z. Sefrioui, J. Santamaria, and J. L. Vicent, Phys. Rev. B 72, 174512 (2005)

[3] G. Blatter, M. V. Feigel'man, V. B. Geshkenbein, A. I. Larkin, and V. M. Vinokur, Rev. Mod. Phys. 66, 1125 (1994)

[4] I. Guillamón, H. Suderow, A. Fernández-Pacheco, J. Sesé, R. Córdoba, J. M. De Teresa, M. R. Ibarra and S. Vieira, Nature Physics 5, 651 (2009)

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Printed electronics from an industrial perspective

Laia Vilar Abril1

1Cetemmsa Technological Center, Av. D´Ernest Lluch 36, Mataró, Spain

[email protected]

Printed electronics is an emerging technology which is increasingly gaining international attention. This technology opens the way for thin-film devices, sensors and actuators which can be large, light-weight, flexible and even stretchable. Moreover, since the manufacturing processes are based on printing techniques compatible with roll-to-roll lines, high throughput at low cost can be achieved. The later has paved the way of printed electronics to application industries such as health, energy, automotive, consumer electronics and packaging. The main technological drivers of this technology will be presented together with some success cases of applications which already reached the market. Furthermore, the research focus of our center in this field will be described. Finally, a concrete example in which imprint lithography and printed electronics are combined to develop ITO-free transparent electrodes enhancing the performance of organic solar cells will be discussed [1]. References [1] Ignasi Burgués-Ceballos, Nikolaos Kehagias, Clivia M. Sotomayor-Torres, Mariano Campoy-Quiles and Paul Lacharmoise, Solar Energy Materials and Solar Cells 127, 50-57 (2014) Figures

Figure 1: (left) Imprint process to embed printd silver grids. (right) Performance of printed rogacni solar cells with different anode structures.

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Challenges in nano-patterning of epitaxial graphene grown on Silicon Carbide semi-insulating wafers

Philippe Godignon1, Narcis Mestres2, Gemma Rius3, Francesc Perez-Murano1

1Centro Nacional de Microelectrónica (CNM-CSIC), Campus UAB, Cerdanyola del Valles, Barcelona, Spain 2Instituto de Ciencias de Materiales de Barcelona (ICMAB-CSIC), Campus UAB, Cerdanyola, Barcelona, Spain

3 Nagoya Institute of Technology, Gokiso, Showa, 466-8555 Nagoya, Japan

[email protected]

Currently, the most promising technique to produce graphene at wafer-scale for industrial purposes seems to be epitaxial growth either by chemical vapor deposition (CVD) on a metallic substrate or by heating a SiC substrate up to the graphitization temperature. In the first case, because the metallic film is electrically conducting, the graphene film needs to be transferred to an insulating substrate for applications based on electronic transport. In the second case, the graphene can be directly used on the insulating SiC surface. Silicon sublimation from the SiC causes a carbon rich surface that nucleates an epitaxial graphene layer. The graphene growth rate was found to depend on the specific polar SiC crystal face: graphene forms continuous layer on Si-face (Fig 1a), while under certain growth conditions, graphene flakes can be obtained on the C-face the surface (Fig 1b). In both case, resulting surface is composed of SiC steps with micrometer wide terraces (Fig 1a). It has been shown that the graphene grown on the terraces sidewall is of poor quality. Then, lithography processes must be aligned with the terraces. In the case of graphene flakes on C-Face, the flake must be localised and lithography must be done based on the flake position. A a consequence, most of lithography steps must be done using electron beam lithography. An alternative to this standard technique is to growth the graphene on pre-patterned wafers with a template. A material able to withstand high temperature must be used as mask such as AlN (Fig 1c) [1] or Si3N4. On the other hand, nanoribbons on SiC combine the high mobilities of graphene on SiC with a gap opening capability thanks to quantum confinement observed in nanoribbons. Typically, the gap energy separation between the sub-bands is inversely proportional to the ribbon width, as well as on the edges type of the ribbons. Ribbons obtained by plasma etching after ebeam lithography typically create rough edges that cause electron scatters and strong localization effects appear. As an alternative to ebeam lithography, Local Anodic Oxidation (LAO) has been tested to define nanoribbons [2-3], as Silicon Carbide can be oxidized forming a SiO2 dielectric layer. An electrically isolated narrow ribbon of graphene can be drawn in such way. However, the best way to generate high performances nanoribbons on SiC is to use selective growth on crystal facets of SiC [4]. Besides the on-axis facets, SiC has other crystal facets with low crystal indies such as the SiC "sidewalls" that connect the terraces on the on-axis wafer surface. These low-index facets grouped as (110n) and (112n) have been used to selectively growth high performances graphene nanoribbons [4]. The facets are created by standard lithography and RIE etching. Then, special growth parameters can be found to get growth only on the facet, the nanoribbon width being defined by the etched sidewall depth. References [1] N. Camara, G. Rius, J.-R. Huntzinger, et als , Applied Physic Letters 93, 123503 (2008) [2] M. Lorenzoni, B. Torre, Applied Physics Letters, 103, 163109 (2013) [3] G. Rius, N. Camara, P. Godignon, F. Perez-Murano, J. Vac. Sci. Technol. B (2009) Vol. 27 (6), 31493152 [4] M. Sprinkle, M. Ruan, Y.Hu, J. Hankinson, M. Rubio et als, Nature Nanotechnology 5, 727-731 (2010) Figures

Fig 1: (a) graphene on SiC Si-face, (a) graphene on SiC C-face (c) graphene grown in AlN template, (d) graphene lithographed by LAO

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DualBeam Nanophototying using Nanobuilder

Chengge Jiao, Pybe Faber, Laurent Roussel

FEI, Achtseweg Noord 5, 5651GG Eindhoven, The Netherlands

[email protected]

Focused Ion Beam (FIB) direct prototyping offers unique benefits in reducing turnaround in Nano device development. NanoBuilder allows patterning of complex shapes automatically layer-by-layer with fully controlling of FIB, SEM, Gas Injection Systems (GIS) and stage. Complicated shapes are able to build up for patterning using Boolean operations. Layers and shapes can pattern in defined sequences. Beam scanning strategies can be specified to individual shapes. Complicated structures could split into smaller shapes and allotted them to different layers. Large nanostructures can be patterned layer-by-layer and site-by-site via multi-sites stage control with the advantage of the layer and the site being independently. Advanced alignment algorithms ensure that the individual layers or sites are accurately aligned without unwanted exposure of the pattern area to ions or electrons. Finally, the patterning of all layers is executed fully automatically with the high performance of ion beam and stage of DualBeam systems. Furthermore, NanoBuilder utilizes FEI’s patterning board with 16-bit resolution (64k×64k pixels) and 40 MHz writing speed.

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Ion Column and Source technology employing Gallium and New Ion Species for

Advanced FIB Nanofabrication

V.Morin, S. Bauerdick, P. Mazarov, L. Bruchhaus, R. Jede

Raith GmbH, Konrad-Adenauer-Allee 8, 44263 Dortmund, Germany [email protected]

An increasing number of applications use focused ion beam (FIB) systems for nanofabrication and rapid prototyping tasks. FIB nanofabrication is a good partner to other lithography techniques providing complementary strengths like direct, resistless, and three-dimensional patterning. Although a FIB process can in many cases be slower than a resist-accelerated process, the relative simplification of the overall nanofabrication approach, especially for the direct processing of novel materials, helps to achieve scientific results faster. We report on our continuous effort to advance FIB technology along with an instrumentation platform dedicated to nanofabrication requirements. The nanofabrication requirements for FIB technology are specific and more demanding in terms of stability, resolution, and the support of new processing techniques. Moreover the type of ion defines the nature of the interaction mechanism with the sample and thus has significant consequences on the resulting nanostructures. Therefore, we have extended the technology towards the stable delivery of multiple ion species selectable into a nanometer-scale focused ion beam by employing a liquid metal alloy ion source (LMAIS). A mass separation filter is incorporated into the column to allow for fast and easy switching between different ions or clusters within less than a minute [1,2,3]. This provides single and multiple charged species of different mass (Figure 1), e.g. Be, Si, Ge or Au, resulting in significantly different interaction mechanisms. We present and discuss the capabilities of the instrument for sub-20 nm to sub-10 nm nanofabrication (Figure 2) as well as potential applications. Using a Si ion beam for high resolution low contamination milling or a Au ion beam for surface functionalization will be given as examples for a full range of techniques yet to be explored. References [1] B. R. Appleton et al., Nucl. Instrum. Methods B 272, 153 (2012). [2] S. Tongay et al., Appl. Phys. Lett. 100, 073501 (2012). [3] S. Bauerdick et al., JVST B 31 (2013) 06F404. Figures

0 100 200 300 400

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Si++

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A)

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Figure 1: Mass spectrum of a AuSi ion source with various ion species.

Figure 2: Results for milling of a 40 nm gold layer on a bulk sample: 7 nm to 19 nm features obtained with a Be, Si and Au ion beam (from left to right) [5].

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Helium Ion Microscopy – Advancements from 0.35 nm Imaging to Sub

10 nm nanopatterning

Peter Gnauck

Carl Zeiss Microscopy, Carl Zeiss Str. 56, 73447 Oberkochen, Germany [email protected]

The helium ion microscope (HIM) takes advantage of an atomically sharp source to emit a beam of focused He ions so the microscopist today can go beyond imaging resolutions achieved in the Scanning Electron Microscope (SEM). Imaging with ions rather than electrons offers many advantages including the ability to image uncoated non conducting samples at high resolution without damage. Additionally, helium ions can be used to sputter material for nanolithography and nanopatterning applications where sub 10 nm structures are desired. A gallery of helium ion microscopy results will be presented to showcase the capbility and performance of this novel microscope. The HIM has proven invaluable at characterizing uncoated biological samples as well as other soft materials. Features sizes and material removal via conventional Ga FIB systems is now surpassed using HIM. The HIM-FIB has touched a wide array of applications that range from nanomachining pores for single molecule detection to

patterning devices in graphene.

Figure 1: 6.5nm lines written in HSQ resist. Line width is independent of pitch (Courtesy TNO, TU Delft).

Figures

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Electrical detection of ferromagnetic resonance in nanostructures

Soraya Sangiao1,2, Michel Viret1

1Service de Physique de l’Etat Condensé, CEA Saclay, DSM/IRAMIS/SPEC, bat. 772, CNRS URA 2464, F-91191 Gif-sur-Yvette, France

2ARAID / Institute of Nanoscience of Aragon, 50018, Zaragoza, Spain

[email protected]

Ferromagnetic resonance (FMR) has been studied for a long time, traditionally using inductive detection techniques. The trend towards miniaturization in electronics has led to the need for understanding and controlling the magnetization dynamics of nanostructures. Classical inductive techniques do not reach the sensitivity allowing to study the magnetization dynamics in individual magnetic nanostructures. Another mean for the detection of FMR in nanostructures consists in measuring its effect on electrical transport through the anisotropic magneto-resistance (AMR). The AMR effect is generally described by an increase in resistance when electrons are flowing parallel to the magnetization compared to perpendicular to it. The voltage picked up in our measurements arises from the current induced at the rf excitation frequency by the varying flux in the stripe rectified by mixing with the AMR contribution at the rf frequency. The great advantage of this technique is that the signal amplitude is proportional to the extra resistance of AMR origin which in turn can increase when samples sizes decrease. This technique will be illustrated by the study (see the scheme in fig. 1) of the detection of the dynamics of the internal magnetic texture of a unique immobile domain wall in permalloy nanostripes [1]. References [1] S. Sangiao and M. Viret, Physical Review B 89, 104412 (2014) Figures

Figure 1: (a) Sketch of the measurement geometry. (b) Field dependence of the measured rectified voltage at 9 GHz and 0 dBm for different

angles between the static magnetic field and the longitudinal axis of the stripe.

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Detection of the spin Hall effect using lateral spin valves

Miren Isasa1, Mª Carmen Martinez2,3, Estitxu Villamor1, Luis Morellón2,3,, José Mª de Teresa2,3,4, Manuel R. Ibarra2,3, Luis Hueso1,5, Fèlix Casanova1,5

1CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain.

2Laboratorio de microscopía avanzada (LMA), Instituto de nanociencia de Aragón (INA), Universidad de Zaragoza, Edificio I+D, 50018 Zaragoza, Spain.

3Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza, Spain. 4Instituto de Ciencia de Materiales de Aragón (ICMA), Universidad de Zaragoza-CSIC, Facultad de Ciencias, 50009 Zaragoza,

Spain. 5IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Basque Country, Spain.

[email protected]

The discovery of the spin Hall effect (SHE) has introduced a novel way to generate and detect pure spin currents, whare key elements in the field of spintronics. When a charge current flows through a material with a strong spin-orinteraction, a transverse spin current is created via the direct SHE. The reciprocal effect, in which a charge currentcreated from the flow of a pure spin current, is known as the inverse SHE (ISHE). The efficiency to convert chacurrent into spin current, and vice versa, is defined by the spin Hall angle. Currently, there is a great interest in studythe SHE, being the spin pumping technique [1] and the use of lateral spin valves (LSVs) [2] the most extendapproaches. In this work, we will focus on the fabrication and characterization of the SHE in three different metals using a devbased on a LSV geometry (Figure 1). The LSV consists of a FM electrode (permalloy) which is used as a spin-polarizcurrent injector, a NM channel (copper) which transfers the accumulated spins and a detector which is an electrode maof the material that we want to study (MS). These devices are fabricated following a delicate three-step electron-belithography (EBL) process, where a proper alignment of the different EBL steps is important for the optimal performanof the device. The first studied metal is platinum (Pt), which is the prototypical material showing SHE, although there ihuge controversy regarding its magnitude [3]. Another metal is gold (Au), which is interesting because, even with a strospin-orbit coupling, it shows a relatively large spin diffusion length. We have analyzed the spin Hall angle as a functof temperature in both metals, as this enables to separate the different contributions to the SHE. The third material that hbeen chosen is bismuth (Bi), because this semimetal shows unique physical properties in addition to a strong spin-orcoupling. In this case, in contrast to Pt and Au, the conversion of spin current into charge current occurs at the Cuinterface being the inverse Rashba-Edelstein effect (IREE) responsible for it [4]. This would be the first time that IREEdetected using a LSV structure. The authors acknowledge funding from the European Commission under the Marie Curie Actions (2564ITAMOSCINOM) and the European Research Council (257654-SPINTROS), the Spanish MICINN (MAT2012-376and MAT2011-27553-C02) and the Basque Government (PI2011-1). M.I. and E.V. thank the Basque Government their Ph.D. fellowship (BFI-2011-106 and BFI-2010-163). References [1] H. L. Wang et al., Physical Review Letters 112, 197201 (2014). [2] Y. Niimi et al., Physical Review B 89, 054401 (2014). [3] L. Liu et al., arXiv:111.3702 (2011). [4] J. C. Rojas-Sanchez et al., Nat. Comm. 4:2944 (2013). Figures

Figure 1. (a) Scanning electron microscope image of a sample with a device to measure the SHE. The device shows the schematic representation for detecting the ISHE. (b) Non-local resistance for Pt (red line), Au (blue line) and Bi (green

line) detected when measuring in the ISHE configuration at 10 K.

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Thermal characterization of Permalloy nanostripes under short pulsed current excitation

Cristina López1; Eduardo Ramos1; Manuel Muñoz2; Jose L. Prieto1

1Física Aplicada, Universidad Politécnica de Madrid, Madrid, Spain. 2IMM-Instituto de Microelectronica de Madrid, CNM-CSIC, MADRID, Spain.

e-mail: [email protected]

Transport measurements in nanostructures are very important in modern nanotechnology. Due to the small scale of the devices and the large current densities required to achieve most of the applications, Joule heating must be always taken into account, even if the current is introduced in short pulses. Thermal effects at the nanoscale are of particular importance for magnetic systems where the Curie temperature may be reached momentarily. In fact, the movement of magnetic domain walls (DW) in ferromagnetic nanowires, can be encouraged by a thermal gradient [1-4]. Here we present a complete characterization of the thermal behavior of nanostripes with pulsed current excitation. The stripes are deposited by DC magnetron sputtering on a SiO2 substrate patterned by e-beam lithography. The resistance is constantly monitored by a high frequency oscilloscope as the current pulse flows through the nanowire. The results are compared with a Resistance vs Temperature calibration. The experiments are simulated with COMSOL and the parameters required to match the experimental results are discussed within this work. These parameters are then used to extract valuable information of the temperature that cannot be extracted experimentally, such as the temperature in a notch or the thermal gradient in certain regions of the stripe. For devices deposited on substrates with good thermal conductivity, the rise of temperature is not usually large, although it may be important on magnetic materials where the movement of DWs follows the Arrhenius law. In substrates with small thermal conductivity like amorphous SiO2, the temperature of the nanowire can be very large in standard working conditions. For instance, for 400nm-SiO2, the temperature can reach 1000 K on a 10nm thick Permalloy for J=5·107 A/cm2, and it can be 40 % hotter in a notch, with depth one third of the width of the wire. This could be detrimental for some studies but allows large in-plane thermal gradients that may be useful for other applications in spin caloritronics. References [1] K-J. Kim, J-C Lee, S-B Choe, K-H Shin, Appl. Phys. Lett. 92, 192509 (2008) [2] A. Yamaguchi, A. Hirohata, T. Ono, H Miyajima, J. Phys.: Condens. Matter 24, 024201 (2012) [3] H. Fangohr, D.S. Chernyshenko, M. Franchin, T. Fischbacher, G. Meier, Phys. Rev. B, 84, 054437 (2011). [4] J. Torrejon, G. Malinowski, M. Pelloux, R. Weil, A. Thiaville, Phys. Rev. Lett. 109, 106601 (2012) Figures

Figure 1: Real-time temperature in a nanowire during a 200 ns pulse (experimental). Upper left corner: estimated temperature values for a

triangular notch with depth one third of the wire

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Quantum Phase transitions in h-BN/graphene/h-BN heterostructures.

Enrique Diez1, Cayetano Cobaleda1, Sergio Pezzini1,2, Vito Clerico1, Vittorio Bellani2.

1Laboratorio de Bajas Temperaturas y Sala Blanca de Nanotecnología, Universidad de Salamanca. Plaza de la Merced s/n. 37008 Salamanca, Spain.

2Dipartimento di Fisica, Universitá degli studi di Pavia. Via Bassi, 6. I-27100 Pavia, Italy.

[email protected]

For our study we used a bilayer graphene flake enclosed by two h-BN flakes fabricated following the procedure developed by Zomer et al. [1]. The h-BN underneath the graphene (i.e., between the SiO2 and the graphene) is meant to reduce the corrugation and avoid the spurious effects observed when graphene is on top of SiO2. The purpose of the h-BN flake covering the graphene is reduce the contamination of the sample from its exposure to the environment, protecting it from adsorbing charged impurities. By means of SEM nanolithography a Hall bar device was fabricated and shown in Figure 1. We used this sample to study the plateau-plateau transitions that characterize the electrical transport in the quantum Hall regime at magnetic fields up to 9 T and temperatures above 300 mK. We measure independently the exponent of the temperature-induced transition broadening, the critical exponent of the localization length, and the exponent p ruling the temperature scaling of the coherence length, finding consistency with the relation p. Our results questions the validity of a pure Anderson transition, and reveals percolation as the underlying driving mechanism. References [1] P. J. Zomer, S. P. Dash, N. Tombros, and B. J. van Wees. A transfer technique for high mobility graphene devices on commercially available hexagonal boron nitride. Applied Physics Letters, 99:232104, 2011. Figures

Figure 1: Optical image of the bilayer graphene device tailored in the geometry ofa Hall bar and enclosed by two h-BN flakes and used in our quantum phase transition experiments. The green flakes are those of

h-BN .

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Invited talk

Spin-orbitronics, a new direction for spintronics

A. Fert1, V. Cros1, C. Deranlot1, J. Grollier1, C. Moreau-Luchaire1, N. Reyren1, J. Sampaio1, N.

Van Horne1, S. Rohart2, A. Thiaville2, J-P. Attané3, J-C. Rojas-Sanchez1,3, L. Vila3, A.V. Khvalkovskiy5, J-M. de Teresa6.

1UMP CNRS-Thales, 1 Av. Fresnel, Palaiseau, 91767, France and Université Paris-Sud

2LPS, Université Paris-Sud, Orsay, France 3INC, CEA, 38054, Grenoble, France

5Grandis, Inc., 1123 Cadillac Court, Milpitas, California 95035, U.S.A 6ICMA, Univ-Zaragoza-CSIC, Zaragoza, Spain

[email protected]

Classical spintronic devices use the exchange interaction between conduction electron spins and local spins in magnetic materials to create spin-polarized currents or to manipulate nanomagnets by spin transfer from spin-polarized currents. A novel direction of spintronics – that can be called spin-orbitronics - exploits the Spin-Orbit Coupling (SOC) in nonmagnetic materials instead of the exchange interaction in magnetic materials to generate, detect or exploit spin-polarized currents. This opens the way to spin devices made of only nonmagnetic materials and operated without magnetic fields. Spin-orbit coupling can also be used to create new types of topological magnetic objects as the magnetic skyrmions or the Dzyaloshinskii-Moriya domain walls. I will review recent advances in two directions of this field. a) Nucleation, current-induced motion and pinning of individual skyrmions or trains of skyrmions

in films or multilayers: I will focus on skyrmions induced by Dzyaloshinsky-Moriya interactions at interfaces of ferromagnetic layers with materials of large spin-orbit coupling before and I will discuss their potential for applications.

b) Conversion between charge and spin current by SOC (Spin Hall Effect and Edelstein Effect): I

will describe recent experiments and applications to the current-induced motion of magnetic domain

walls and the switching of nanomagnets.

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POSTERS

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Fabrication and cross section investigation of FEBID Co-SiOx binary

systems

M.J. Perez-Roldan1, F. Tatti2, A. Berger1, A. Chuvilin1,3

1CIC nanoGUNE Consolider, Avenida de Tolosa 76, 20018 Donostia-San Sebastian, Spain. 2FEI Electron Optics Achtseweg Noord 5, 5600 KA Eindhoven, The Netherlands.

3Ikerbasque, Basque Foundation for Science, Alameda Urquijo 36-5, 48011 Bilbao, Spain. [email protected]

Focused electron beam induced deposition (FEBID) is a well-known direct-writing technique that has been widely studied in the last decades due to its versatility as micro and nano-fabrication tool [1, 2]. Most recently, the deposition in parallel of two different precursors has also called the attention of several researchers in order to get functionalized deposits in one step fabrication process [3-6]. In these binary alloys the relative flux of the two precursors was varied in order to tune the bulk composition and confer to the deposits different electric and magnetic properties. In this work, binary systems of Co-SiOx in a carbonaceous matrix has been deposited using dicobalt octacarbonyl (Co2(CO)8) and tetraethyl orthosilicate (Si(OC2H5)4) as precursors. The composition distribution in the deposits has been investigated by energy dispersive X-ray spectroscopy (EDX) maps at different deposition conditions. Results showed the presence of internal sub-structures inside the FEBID deposits that were highly influenced by deposition conditions such as refresh time or current applied. References: [1] Huth, M., et al., Beilstein J. Nanotechnol. 3, 597–619, (2012). [2] Utke, I., et al., J. Vac. Sci. Technol. B 26, 1197, (2008). [3] Porrati, F., et al., Nanotechnology. 23, 185702, (2012). [4] Porrati, F., et al., J. Appl. Phys. 113, 053707, (2013). [5] Winhold, M., et al., ACS Nano. 5, 9675, (2011). [6] Che, R.C., et al., Appl. Phys. Lett. 87, 223109, (2005).

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Transport measurements of W-based superconducting films with

thickness modulation grown by Focused-Ion-Beam Induced Deposition.

Ismael García-Serrano1,2, J. Sesé1,2, M.R. Ibarra1,2, J.M. De Teresa1,2,3

1Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Spain.

2 Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA), Universidad de Zaragoza, 50018 Zaragoza, Spain. 3 Instituto de Ciencia de Materiales de Aragón

(ICMA), Universidad de Zaragoza-CSIC, Facultad de Ciencias, Zaragoza, Spain. [email protected]

The vortex dynamics changes its behavior in structures of type-II superconductors with dimensions comparable to the inter-vortex distance, as shown in recent years due to the possibilities of nanofabrication. It’s well known that W-based nanostructures grown by Focused-Ion-Beam induced deposition (FIBID) have superconducting properties (type II) [1]. Shape modulation is easily achieved with this technique, making this material suitable for investigations of the vortex dynamics in tailored pinning landscapes. Previously published works have emphasized that the vortex behavior can be modulated in this material [2, 3]. In order to investigate the effect of a surface modulation on the vortex distribution, we have grown W-based films with thickness modulation along one direction. The modulation has been achieved with different periodicities (between 60 and 100 nm) by optimization of the growth parameters. Cross-sectional SEM analysis has been used to measure the sample dimensions. The figure 1 shows a sample of 50 nm thickness and 100 nm modulation along the Y direction grown on a silicon nitride substrate. Transport experiments in these films have been done as a function of temperature, current and magnetic field. The aim of these measurements is to obtain information about how the thickness modulation can affect the superconductor characteristic parameters. References [1] I. Guillamón, H. Suderow, S. Vieira, A Fernández-Pacheco, J. Sesé, R. Córdoba, J. M. De Teresa, and

M. R. Ibarra, “Nanoscale superconducting properties of amorphous W-based deposits grown with a focused-ion-beam,” New J. Phys., vol. 10, no. 9, p. 093005, Sep. 2008.

[2] R. Córdoba, T. I. Baturina, J. Sesé, a Y. Mironov, J. M. De Teresa, M. R. Ibarra, D. a Nasimov, a K. Gutakovskii, a V Latyshev, I. Guillamón, H. Suderow, S. Vieira, M. R. Baklanov, J. J. Palacios, and V. M. Vinokur, “Magnetic field-induced dissipation-free state in superconducting nanostructures.,” Nat. Commun., vol. 4, p. 1437, Jan. 2013.

[3] I. Guillamón, H. Suderow, a. Fernández-Pacheco, J. Sesé, R. Córdoba, J. M. De Teresa, M. R. Ibarra, and S. Vieira, “Direct observation of melting in a two-dimensional superconducting vortex lattice,” Nat. Phys., vol. 5, no. 9, pp. 651–655, Aug. 2009.

[4] De Teresa, J. M. & Cordoba, R. “Arrays of Densely-Packed Isolated Nanowires by Focused Beam Induced Deposition Plus Ar+ Milling.”, ACS Nano (2014), 8 (4), pp 3788–3795.

Figures

Figure 1: A cross-sectional image of a W-based film with thickness modulation in one direction, grown on Si3N4 substrate. The maximum thickness of this sample is around 50 nm and the distance between lines 100 nm.

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Resistive Switching phenomena in La1-xSrxMnO3-x compounds:

A local probe microscopy study

J.C. Gonzalez-Rosillo1, R. Ortega1,2, I. Maggio-Aprile3, M. Coll1, A. Palau1, J. Suñé2, X. Obradors1, T. Puig1

1Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, 08193, Bellaterra

(Barcelona), Spain 2Departament d’Enginyeria Electrònica, Universitat Autònoma de Barcelona, Campus de la UAB, 08193,

Bellaterra (Barcelona), Spain 3DPMC-MaNEP, University of Geneva, 24 quai E. Ansermet, Geneva, Switzerland

[email protected]

In recent years, the field of materials showing resistive switching (RS) phenomena, where two (or more) reversible resistance states can be induced upon application of an electric field, has emerged with outstanding results in the area of new RRAM based electronic devices. This phenomenon has been observed in many oxide systems, in particular in complex oxides with a metal-to-insulator transition (MIT) that can be controlled by cation but also anion doping, like compounds belonging to the La1-xSrxMnO3-x family. We early proved [1] that reversible transitions from low resistive (LR) to high resistivity (HR) state and even multilevel switching was possible at the nanoscale in La0.7Sr0.3MnO3 films by means of a Conductive-Scanning Probe Microscope (C-SPM), but the physical mechanism responsible of the transition was not well understood, although oxygen vacancies mobility is believed to play a fundamental role. Advancing in the understanding of the switching process would enable further and faster integration of these systems in the applications’ niche. To do so, we have extended our studies by varying the thickness and the Sr content of the films. These two parameters allow the fine tuning of the MIT and the physical properties of the film (resistivity, Tc, RS parameters…). Furthermore, we can also evaluate the RS effect by IV characteristics using metallic electrodes in lateral devices, and combining both nano and micro characterization techniques open the possibility to richer and finer studies. In particular, we are able to create HR patterns generated by C-SPM in large HR areas (~ 60-80 µm), which allow us to evaluate different properties of the non-volatile HR state. We present scanning tunneling microscopy and spectroscopic studies (STM/STS) where we can infer insight into the electronic behavior both in the pristine state and in the high resistance state. We present I-V and dI/dV curves which we show different behavior of the electrons in the vicinity of the Fermi level in the different states. References [1] C.Moreno, C. Munuera, S. Valencia, X. Obradors, C. Ocal, Nano Lett., 10, 3828 (2010)

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Fabrication of superconducting/magnetic bilayers with periodic thickness modulation in the magnetic component to study anisotropic

dissipation.

L. Ruiz-Valdepeñas,1 A. Hierro-Rodriguez,2,3 M. Vélez, 2 E. Navarro, 1 J. I. Martín, 2,3 L. M. Álvarez-Prado, 2,3 J. M. Alameda2,3 and J. L. Vicent1,4

1 Dpto. Física de Materiales, Universidad Complutense, 28040 Madrid, Spain

2 Departamento de Física, Universidad de Oviedo, 33007 Oviedo, Spain 3 CINN, (CSIC-UO-P. Asturias), Llanera, Spain

4IMDEA-Nanociencia, Cantoblanco, 28049 Madrid, Spain

[email protected]

Nanostructured multilayers have been fabricated by electron beam and optical lithography techniques to study superconductor- ferromagnet proximity effect. The samples consist of a Nb film grown on top of a periodic thickness modulated amorphous NdCo5 ferromagnetic layer [1]. First, a square of NdCo5 50 nm thick is grown on a silicon substrate. Using electron beam lithography, 700 nm width stripes are defined with a period of 1.4 m. These stripes are used to etch 15 nm depth grooves in the NdCo5 layer by ion milling. Finally a 50 nm thick Nb film is deposited above the nanostructured NdCo5. The dissipation behavior has been studied by means of transport measurements. To perform these measurements, contact paths are defined by optical lithography and reactive ion etching. Due to the thickness modulation, the resulting hybrid structure can mimic the behavior observed in multilayers [2], but in this case the multilayer is extended along the substrate plane as a lateral multilayer. Near the critical temperature this lateral multilayer may have a 1D-2D crossover instead of the well-known 2D-3D crossover [2]. For magnetic fields applied perpendicular to the film, this sample enables us to study the dissipation of vortex flowing perpendicular or parallel to the NdCo5 stripes. References

[1] A. Hierro-Rodriguez, R. Cid, M. Vélez, G. Rodriguez-Rodriguez, J. I. Martín, L. M. Álvarez-Prado, and J. M. Alameda, Phys.Rev. Lett., 109, 11, 117202, (2012)

[2] C. Chun, G.-G. Zheng, J. L. Vicent, and I. K. Schuller, Phys. Rev. B, 29, 9, 4915, (1984)

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Fabrication and characterization of magneto-plasmonic

nanostructures arrays patterned by electron beam lithography

F. Galvez1, J. del Valle1, D. Perez de Lara2, M. A. Garcia3 and J. L. Vicent1,2

1 Dpto. Física de Materiales, Universidad Complutense de Madrid, 28040 Madrid, Spain 2IMDEA Nanociencia, Cantoblanco, 28049 Madrid, Spain

3Instituto de Cerámica y Vidrio (ICV-CSIC), Cantoblanco, 28049 Madrid, Spain [email protected]

We present the fabrication and characterization of permalloy/gold nanoscale nanobars. Electron beam lithography has been used to pattern the nanostructures on PMMA onto a silicon substrate. The deposition has been carried out by DC magnetron sputtering for the permalloy layer and electron beam evaporation for the upper gold layer. The dimensions of the nanobars are 150x350 nm, and the thickness of the permalloy and gold layers are 50 and 45 nm respectively. The nanostructures exhibit the surface plasmon resonance (SPR) of the Au elements that has been measured by optical spectroscopy in reflection mode. For the characterization of the magnetic properties we have used magneto-optic Kerr effect. In order to reduce the background contribution from the substrate, we configured the setup to measure the first maximum in the diffraction pattern of the array. Finally we study the possible effects of the excitation of SPR on the magnetic properties of the nanostructure. In particular we focused on the possibility to heat the nanostructure by exciting the SPR with a laser and check whether the induced heating modifies the magnetization curve of the nanobars.

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Self-assembled Permalloy nanodisks for biomedical applications

M. Goiriena-Goikoetxea1*, J. Feuchtwanger2, M.L. Fdez-Gubieda1,2 and A. García-

Arribas1,2

1BCMaterials, Universidad del País Vasco (UPV/EHU), Barrio de Sarriena s/n, 48940, Leioa, Spain.

2Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), Barrio de Sarriena s/n, 48940, Leioa, Spain.

*e mail: [email protected]

Magnetic nanoparticles are extensively studied for biomedical applications because their size are comparable to biological entities, while providing remote capabilities of actuation [1]. Disk shaped ferromagnetic nanoparticles add attractive possibilities to these characteristics. First, Permalloy (Py) nanodisks display much higher saturation magnetization values than oxide nanoparticles and second, depending on their geometry, they can present a spin vortex configuration which leads to net zero magnetization at remanence, eliminating the problem of particle agglomeration. Therefore, Py nanodisks present a huge potential for biomedical applications, ranging from cancer cell destroy by hyperthermia or mechanical actuation to MRI contrast enhancement and drug delivery [2]. While oxide nanoparticles are chemically synthetized, nanodisk physical fabrication methods offer higher control on particle size and the possibility of choosing among a larger spectrum of materials. Electron beam lithography (EBL) and Photolithography allow for tightly controlled fabrication of particles with virtually any size, shape and composition. The use of these techniques, though, imply a very low yield production (in the case of EBL) and the use of quite sophisticated and expensive equipment. As an alternative, self-assembling fabrication routes provide high volume and low cost production of well-defined Py nanodisks. In this work we present the results obtained by two different approaches: Hole-mask Colloidal Lithography (HCL) [3] and Nanosphere Lithography (NSL) [4]. HCL utilizes the definition of a dense hole-pattern in a sacrificial resist layer onto which a layer of Py is deposited. Py disks are produced after lift-of of the resist layer. The NSL route proposed here relies on the patterning of nanopillars using self-assembled polystyrene spheres, onto which the Py disks are formed by deposition. The results obtained show promising structures. The magnetic characterization performed by Magneto-Optical Kerr Effect (MOKE) indicates that vortex and single-domain states can be present [5]. References [1] Q. A. Pankhurst et al. Journal of Physics D: Applied Physics, 167 (2003). [2] D.-H. Kim, et. al. Nature Materials, 9 165 (2009). [3] H. Fredriksson, et. al Advanced Materials, 19 4297 (2007). [4] P. Tiberto, et. al, Journal of Nanoparticle Research, 13 4211 (2011). [5] G. Shimon, et. al, Physical Review B, 87 214422 (2013).

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Nanostructuring Thin Polymer Films with 2 and 3-Beam

Single Pulse Laser Interference Lithography

I. Martín-Fabiani,1 S. Riedel,2 D.R. Rueda,1 J. Siegel,3 J. Boneberg,2 T.A. Ezquerra1 and A. Nogales1

1 Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006 Madrid, Spain 2 University of Konstanz, Fach 676, 78457 Konstanz, Germany

3 Instituto de Óptica (IO-CSIC), Serrano 121, 28006 Madrid, Spain aurora.nogalesEmail@address

In this work we report the application of 2 and 3-beam Single Pulse Laser Interference Lithography to thin polymer films of Poly (trimethylene terephthalate) (PTT). Previous work have proven the possibility of nanostructuring polymer surfaces by imprinting optical near fields.[1] In this case we show that, by irradiating the sample surface with a single pulse from two or three coherent beams and changing the incidence angles, it is possible to the fabricate polymer micro and nanogratings over large areas as well as nanocavities arranged in a distorted hexagonal lattice. Their characterization in real space by atomic force microscopy (AFM) and scanning electron microscopy (SEM) has allowed us to investigate the formation mechanism of the microgratings, identifying three different steps in the ablation process depending on the local fluence. Moreover, characterization in reciprocal space by grazing incidence small angle x-ray scattering (GISAXS) of the nanocavities is in agreement with the information provided by AFM and supports the existence of large areas where two-dimensional partial crystalline order is present. References [1] I Martín-Fabiani, J Siegel, S Riedel, J Boneberg, TA. Ezquerra, A Nogales, ACS

Appl. Mater. Interfaces 5 (21), 11402–11408, (2013) Figures

Figure 1: Optical setup used in the Single Pulse Laser Interference Lithography experiments.

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Effect of oxygen on EBID deposited platinum structures

E. Villamor,1 J.J.L. Mulders,2 P.H.F. Trompenaars2

1 CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country, Spain 2 FEI Electron Optics, 5651GG Eindhoven, The Netherlands

[email protected]

Electron beam induced deposition (EBID) is a direct write technique based on the electron-beam (e-beam) induced dissociation of precursor molecules [1]. The fact of being a direct technique can provide several advantages as compared to conventional lithography techniques, where intermediate steps such as resist coating, exposure, developing and lift off are required. The drawback of EBID is the low purity of most of the deposited materials due to an incomplete dissociation of the precursor molecules [2]. For the present work, we deposited platinum (Pt) structures from a methylcyclopentadienyl trimethyl platinum (MeCpPtMe3) precursor, and studied the effect of oxygen (O2) in the purification of such structures. The experimental work was carried out at a FEI Helios NanoLab 650. Pt structures were deposited (5 kV and 1.6 nA) and e-beam irradiated afterwards (5 kV and 26 nA) under a constant O2 flux at room temperature. Figure 1(a) shows that the ratio between the net intensities of carbon (CK) and PtM (from the EDX analysis) decreases with the applied dose, until a completely pure Pt structure is obtained [3]. On the other hand, the ratio between the OK and PtM net intensities increases with the irradiation dose. However, due to a disappearance of the O peak with time, we conclude that the O2 is physically absorbed by the Pt and oxidation of Pt does not occur. The electrical resistance of the deposited structures is obtained as a function of the dose (see Fig. 1(b)), improving from 249 to 54 with increasing the dose, whereas a standard deposition presents a resistance of the order of k [3]. For the highest applied dose, after measuring the volume of the wire, a resistivity of 88 cm is calculated, only 8 times higher than bulk Pt. Finally, based on these results, a simultaneous deposition and purification process is developed, where the precursor supply, and thus the Pt deposition, takes place under a constant O2 flux. This work was supported by NanoNextNL, a programme of the Dutch Government and 130 partners. E.V. thanks the Basque Government for a PhD fellowship (Grant No. 2010-163). References [1] I. Utke, P. Hoffmann, and J. Melngailis, J. Vac. Sci. Technol. B 26, 1197 (2008). [2] J.J.L. Mulders, L.M. Belova, and A. Riazanova, Nanotechnology 22, 055302 (2011). [3] S. Mehendale, J.J.L. Mulders, and P.H.F. Trompenaars, Nanotechnology 24, 145303 (2013). Figures

ure 1: (a) Ratio of net intensities (measured by EDX) of C and Pt, and O and Pt as a function of the e-beamradiation dose (for an e-beam current of 26 nA) during a constant O flux for Pt purification. (b) Electrical istance of the deposited wires as a function of the e-beam irradiation dose (for an e-beam current of 26 nA

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Perylendiimide-based second-order Distributed Feedback Lasers fabricated by Thermal Nanoimprint Lithography

A. Retolaza1,2, A. Juarros1,2, D. Otaduy1,2, S. Merino1,2, E.M. Calzado3, J.M.

Villalvilla4, M. Morales-Vidal4, P.G. Boj5, J.A. Quintana5, V. Navarro-Fuster4, M.A. Díaz-García4

1Micro and Nano Fabrication Unit, IK4-Tekniker, C/ Iñaki Goenaga 5, 20600 Eibar, Spain

2CIC microGUNE, Goiru Kalea 9 Polo Innovación Garaia, 20500 Arrasate-Mondragón, Spain 3Dpto. de Física, Ingeniería de Sistemas y Teoría de la señal and Instituto Universitario de Materiales de

Alicante (IUMA), Universidad de Alicante, 03080 Alicante, Spain 4Dpto. de Física Aplicada and IUMA, Universidad de Alicante, 03080 Alicante, Spain

5Dpto. de Óptica and IUMA, Universidad de Alicante, 03080, Alicante, Spain [email protected]

In the past years organic solid-state lasers (OSLs) have been widely investigated due to the advantages of easy processability, chemical versatility, wavelength tuneability and low cost offered by organic materials [1,2]. Among the various types of OSLs reported in the literature, distributed feedback (DFB) lasers have been particularly successful [1,2], since they present several advantages, such as easy deposition of the organic film, low thresholds, single mode emission and no need of mirrors, and they also have potential interest in various applications, such as optical communications, biosensing and chemical sensing [3,4]. Among the methods generally used for grating engraving, nanoimprint lithography (NIL) [5] is one of the most promising technologies, even for future industrial applications, due to its high throughput, high resolution (sub-10 nm) and low cost. In this work the fabrication of perylendiimide-based second-order DFBs will be reported, and the effect of different parameters such as the grating depth, active film thickness and pump size on the laser performance will be analyzed [6]. Moreover, the potential use of these DFB devices as biosensor will be studied. For that, the laser wavelength shift experienced when a liquid or solid layer of material is deposited on top of the device will be studied. The influence on the sensor sensitivity of changing the thickness of the active film and the addition of TiO2 top layer will be also analyzed. References [1] D.W. Samuel, G.A. Turnbull, Chem. Rev., 107, 1272 (2007) [2] J. Clark, G. Lanzani, Nat. Photonics, 4, 438 (2010) [3] M. Lu, S.S. Choi, C.J. Wagner, J.G. Eden, B.T. Cunningham, Appl. Phys. Lett., 92, 261502 (2008) [4] C. Vannahme, M.C. Leung, F. Richter, C.L.C. Smith, P.G. Hermannson, A. Kristensen, “Laser Photonics Rev.”, 7, 1036 (2013) [5] S.Y. Chou, P.R. Krauss, P.J. Renstrom, Appl. Phys. Lett. 67, 3114 (1995) [6] E.M. Calzado, J.M. Villalvilla, P.G. Boj, J.A. Quintana, V. Navarro, A. Retolaza, S. Merino, M.A. Díaz-García, Appl. Phys. Letters, 101, 223303 (2012)

Figures Figure 1: a) SEM micrograph of the cross-section of DFB device by thermal-NIL and spin-coating process. b) Laser

thresholds for DFB devices with two grating depths (d = 120 nm and d = 400 nm) as a function of the excitation area over the sample expressed as energy density (right axis) and power density (left axis).

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Lithography techniques for graphene-based nanodevices

Inés Serrano-Esparza1,2, Jan Michalik2,3, M.R. Ibarra2,3 and José María de Teresa1, 2, 3

1 Instituto de Ciencia de Materiales de Aragón, C/Pedro Cerbuna 12, 50009, Zaragoza, Spain

2 Departamento de Física de la Materia Condensa, C/Pedro Cerbuna 12, 50009, Zaragoza, Spain 3 Laboratorio de Microscopias Avanzadas, C/ Mariano Esquillor s/n, 50018, Zaragoza, Spain

[email protected]

The recent discovery of graphene [1] has opened a broad field of study which might lead to some amazing applications in the future, such as: flexible screens, intelligent contact lenses, light planes, etc. However, far from reality, a lot of work must be done in order to optimize the lithography process. The first point is the graphene production. So far, the graphene of best quality is the exfoliated one [2] and devices based on this graphene must be taken as the target for other kinds of graphene (such as, chemical vapor deposition (CVD), growth on SiC, liquid phase exfoliation, etc.[2]). We are going to indicate our different approaches to make devices using exfoliated graphene: we could either deposit the graphene flakes and make contacts on it (Figure 1a); or make the contacts first and deposit the graphene (Figure 1b). For the first option, we should use EBL and positive resist (like PMMA 950k); whereas, for the second option, we can also use optical lithography. In both cases, negative resist (like AR-N 7700) can be used to pattern graphene in a desirable form. Finally, we will show different techniques to transfer exfoliated graphene on top of metallic contacts (using PMMA resist, PDMS gel). To sum up, we will show different lithography approaches and will discuss which one is the best candidate for future production of graphene-based devices in terms of graphene damage and its possible introduction in the current Si-based production line (for example using CVD-graphene). References

[1] K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, “Electric field effect in atomically thin carbon films.,” Science, vol. 306, no. 5696, pp. 666–9, Oct. 2004.

[2] F. Bonaccorso, A. Lombardo, T. Hasan, Z. Sun, L. Colombo, and A. C. Ferrari, “Production and processing of graphene and 2d crystals,” Mater. Today, vol. 15, no. 12, pp. 564–589, 2012.

Figures

Figure 1: Left. Device where contacts were grown on top of graphene flake, previously patterned with O2 plasma. Right. Device where graphene was deposited over contacts.

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Standardization of deposition techniques for SnO2

nanoparticles on microhoplates for gas sensing applications

Eguizábal, A1; Pallarés, M.C2; Gracia-Lostao, A.I2,3; Pellejero, I1; Sesé, J1; Pina M.P1

1 Nanoscience Institute of Aragon, 50018, Zaragoza, Spain 2Advanced Microscopies Laboratory, Nanoscience Institute of Aragon, 50018, Zaragoza, Spain

3Fundación Araid, Spain [email protected]; [email protected]

Unlike the progress and matureness in microfabrication, the incorporation of nanostructured materials (nanoparticles, nanowires, nanoshells, nanoplates, nanograss) prepared by controllable-scalable synthesis by reliable and feasible deposition techniques over suitable platforms has been scarcely attempted in the literature in a systematic way. Thus, the development of outperforming nanosensors by controlling the properties (size and shape control, surface area, thermal stability, orientation, crystallinity) of the sensing material at the nanoscale should also considered the peculiarities imposed by the transducer itself (surface energy, zeta potential, roughness, thermal expansion coefficient). In this work, tiny SnO2 nanoparticles prepared by a facile, scalable and sustainable synthetic route [1] have been deployed over reference Si substrates and also commercial microhotplates (KMHP-100) by different techniques: micro-dropping, spin-coating, opaline method, did-pen nanolithography. Special emphasis has also been devoted to the chemical functionalization of the transducer surface by means of polyelectrolytes, organosilanes and thiolated compounds. References [1] P. Manjula, R. Boppella, S.V. Manorama, ACS Applied Materials & Interfaces 4, 6252 (2012). Figures

Figure 1: Deposition Strategies for monodisperse SnO2 nanoparticles (i.e. 50 nm in size) on commercial microhotplates for sensing applications.

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Fabrication of a thin layer MoS2 field effect transistor

by oxidation scanning probe lithography

Francisco Espinosa1, Kolyo Marinov2, Yu Kyoung Ryu Cho1, Ricardo Garcia1 and Andras Kis2

1Instituto de Ciencia de Materiales, CSIC, Sor Juana Inés de la Cruz 3, Madrid, Spain

2École Polytechnique Fédérale de Lausanne, LANES, Station 17, Lausanne, Switzeland [email protected]

MoS2 thin layers offer a two-dimensional platform to develop devices such as field effect transistors (FETs) with very high mobilities and good mechanical properties [1-3]. Moreover, MoS2 monolayers present a direct bandgap which makes them very attractive for optoelectronic applications [4]. The positioning capabilities and the resolution of oxidation scanning probe lithography (oSPL) [5] can be used to make MoS2 FETs with very small channels. Here, we have applied oxidation SPL to fabricate a MoS2 transistor with a channel width of 300 nm. The electrical characterization of the device before and after the fabrication of the barriers by oSPL confirms the changes in the channel width. This work shows the potential of oSPL to pattern novel two dimensional electron materials. We acknowledge support from the European Union under Grant Agreement No. 318804 (SNM). References [1] B. Radisavljevic, A. Radenovic, J. Brivio, V. Giacometti and A. Kis, Nature Nanotechnology 6, 147 (2011) [2] B. Radisavljevic and A. Kis, Nature Materials, 12 815 (2013) [3] S. Bertolazzi, J. Brivio, and A. Kis, ACS Nano, 5, 9703 (2011) [4] O. Lopez-Sanchez, D. Lembke, M. Kayci, A. Radenovic and A. Kis, Nature Nanotechnology, 8 497 (2013) [5] R. V. Martínez, J. Martínez and R. García, Nanotechnology 21, 245301 (2010)

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Mechano-Selective Bacteria Surface Adhersion

Felipe Viela1, Manuel Rodriguez1, Aitziber Lopez Cortajarena1,2,, Santiago Casado1, and Isabel Rodriguez1

1 Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanoscience), C/Faraday 9, Ciudad Universitaria de Cantoblanco, Madrid 28049, Spain.

2CNB-CSIC-IMDEA Nanociencia Associated Unit "Unidad de Nanobiotecnología" 28049-Madrid, Spain.

E-mail: [email protected]

Most bacteria live attached to surfaces as means of survival. Once bacteria attach onto a surface, they proliferate and form a sessile community of bacteria called biofilm in which the microorganisms are shielded in a self-produced matrix. Biofilms are notoriously resistant to antibiotic treatment and to immune defenses and as such, they are either impossible or very difficult to eliminate. Accordingly, the most effective means to avoid bacterial infection is by preventing the early stages of bacteria attachment and biofilm formation. Our approach to develop antibacterial surfaces is based on using strictly physical means to affect bacteria attachment exploiting the response of bacteria to nanomechanical surface characteristics such as stiffness [1, 2]. To this end, we fabricate mechanoselective surfaces based on dense high aspect ratio high density pillar structures in polymers. This topography reduces the effective stiffness of a substrate and alongside, it reduces the effective contacting area of the bacteria with the surface. The effective stiffness of the surface is decided by the topographical design with precise dimensions in terms of pillar diameter, height and density. The mechano-selective topographies are fabricated via polymer replication using thermal nanoimprinting. Initially, molds containing the negative geometry of pillars are fabricated in silicon by micromachining techniques. The molds are then imprinted onto thermoplastic substrates like polycarbonate and polypropylene.The effective stiffness of the textured substrates is calculated from the force–distance (f-d) curves of indentation experiments applying Oliver and Pharr analysis [3].

Preliminary experiments of adhesion of Staphylococcus aureus onto textured surfaces indicate that the topography disrupts the formation of the continuous biofilm that is seen on flat pristine surfaces (Fig 1A). On 500 nm pillared surfaces, the S. aureus attaches individually within the 500 nm pillar gaps where the spacing allows the coccus to reach the bottom of the substrate (Fig. 1B). On the other hand, the adhesion of S aureus on to 200 nm dense pillared surfaces is much reduced as this topography does not allow the bacteria to reach the base surface, and only a few bacteria adhere onto the top of the pillars (Fig 1C) .Nanoindetation tests indicated that the effective stiffness of this substrate is significantly reduced compared to the stiffness of the pristine polymer substrate.

References [1] A.I. Hochbaum, J. Aizenberg. Nano Lett., vol 10, pp 3717–3721 (2010) [2] E.P. Ivanova, J. Hasan, H.K. Webb, V.K. Truong, G.S. Watson, J.A. Watson, V.A. Baulin , S. Pogodin, J.Y. Wang, M.J. Tobin, C. Löbbe, R.J. Crawford. Small vol 8, pp 2489–2494 (2012) [3] W.C. Oliver, G.M. Pharr. J. Mater Res, vol 19, pp 3-20 (2004)

Figures

Figure 1: A) Comparison of the S. aureus attachment onto flat (A) and pillared surfaces after 24 hours of incubation. B) S. aureus attached over 500 nm pillars, C) S. aureus attached over 200 nm pillars

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Fabricating devices beyond the limits of electron

beam lithography

Libe Arzubiaga1, Emmanouil Masourakis1, Estitxu Villamor1, Roger Llopis1, Fèlix Casanova1,2, Luis E. Hueso1,2

1CIC Nanogune, Tolosa Hiribidea 76 20018, Donostia-San Sebastián, Spain

2IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain [email protected]

Fabricating devices for research applications can be very challenging, especially when the experiments aim at probing objects as small as metal nanoclusters, isolated molecules or even single atoms [1]. Direct write electron beam lithography (EBL) is probably the most suitable technique for facing this challenge, due to its versatility and its high resolution (around 10 nm). However, sometimes the elements and feature sizes conceived for novel devices go beyond the limits of the state-of-the-art e-beam writers. Several strategies have helped to fill in the gap between the resolution capability of the lithographic resources and the actual requirements for the designed experiments [2, 3]. As an example of such strategies, we present two different approaches aimed for overcoming the limits of EBL: electromigration and oxide-overhang masking. The use of these strategies in combination with EBL has allowed us to obtain a range of devices for different applications, such as: ‐ Lateral spin valves with nanoconstrictions. ‐ Single electron transistors with metallic quantum dots. ‐ High aspect ratio nanogaps for molecular electronics. We would like to acknowledge financial support from he European Union 7th Framework Programme under the European Research Council (Grant 257654-SPINTROS), the Marie Curie Actions (PIRG06-GA-2009-256470), and the NMP project (NMP3-SL-2011-263104- HINTS); the Spanish Ministry of Economy under Project No. MAT2012-37638 as well as by the Basque Government through Project No. PI2011-1. References [1] Vincent, R., Klyatskaya, S., Ruben, M., Wensdorfer, W., Balestro, F., Nature 488, 357 (2012) [2] Fursina, A., Lee, S., Sofin, R.G.S., Shvets, I.V., Natelson, D., Appl. Phys. Lett. 92, 113102 (2006) [3] Song, H., Kim, Y., Jang, Y.H., Jeong, H. Reed, M.A., Nature 462, 1039 (2009) Figures

Figure 1: Lateral spin valve with an electromigrated nanoconstriction.

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Control of magnetic domain wall motion in Co microwires by

tridimensional e-beam lithographied structures

C. Blanco-Roldán1,2, C. Quirós1,2, G. Rodriguez-Rodriguez3, J. I. Martín1,2 and J. M. Alameda1,2

1Departamento de Física, Universidad de Oviedo, Avda. Calvo Sotelo s/n, 33007 Oviedo, Spain 2Centro de Investigación en Nanomateriales y Nanotecnología CINN (CSIC, Universidad de

Oviedo), Avda. de la Vega 4-6, 33940 El Entrego, Spain 3 Madrid Institute for Advanced studies in Nanoscience (IMDEA nanoscience) c/Faraday 9,

28049, Campus de Cantoblanco, Madrid. [email protected]

In the last few years, being capable of controlling the motion of magnetic domain walls has been a matter of increasing attention as it is a key factor in the development of modern memory devices [1]. In this work we present how wall motion can be pinned along a cobalt microwire by the presence of a cobalt 3D e-beam lithographied bridge that crosses over it. Co microwires and bridges are both patterned over a Si substrate by electron beam lithography in a multistep method consisting in double exposition of the stripes and bridges separately. First, Si substrates are spin-coated with PMMA to pattern pairs of 50 µm length x 3 µm width wires with a needle-like shape and alignment marks, then a 40 nm Co film is grown by magnetron sputtering and Co wires are obtained after a lift-off process. Subsequently the sample is again spin-coated with a bilayer combination of PMMA and MMA in order to achieve a more suitable T-shape sidewall profile, due to the different resist sensibility to an electron flux. Bridges are then patterned over one Co wire in each pair using the previously lithographied alignment marks. Typical sizes of these Co bridges, also grown by magnetron sputtering, are 8 µm length, 3 µm width and 250 nm thickness, with 4 x 3 µm pillars, and rise over the substrate surface 240 nm on average [Figure 1(a)]. Magnetization process in these systems has been analyzed by Kerr Microscopy in longitudinal geometry. It is found that when a magnetic field is applied in the direction along the Co microwires, Co bridges act as pinning sites for the magnetic wall coming from the nucleation area [Figure 1(b)], confirming that this kind of 3D microstructures can be a useful tool to control magnetic domain wall motion. Acknowledgements Work supported by the Spanish MICINN FIS2008-06249 and CSIC JAE Predoc grants. We thank A. Hierro-Rodríguez for his helpful advice. References [1] S. S. P. Parkin, M. Hayashi and L. Thomas, Science 320, 190 (2008) Figures

Figure 1: (a) Scanning Electron Microscopy (SEM) image showing the patterned microstructures: a Co bridge is seen clearly above the Co wire with a needle-like shape to control domain nucleation and wall propagation direction. (b) Propagation of the

magnetic wall is pinned by the effect of the Co bridge.

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Laser Induced Periodic Surface Structures (LIPSS) on

Semiconducting Polymers: Poly(3-alkylthiophene)

A. Rodríguez-Rodríguez1, E. Rebollar2, M. Soccio3, T.A. Ezquerra1,

M. Castillejo2, M.C. García-Gutiérrez1

1Instituto de Estructura de la Materia, IEM-CSIC. C/ Serrano 121, Madrid 28006, Spain. 2Instituto de Química Física Rocasolano, IQFR-CSIC, C/Serrano 119, Madrid 28006,

Spain 3Dipartamento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Universitá di

Bologna, Via Terracini 28, Bologna 40131, Italy.

[email protected]

Sub-microstructured thin polymer films on solid substrates are used in many technological applications such as optical elements, photonic crystals, high-density magnetic data storage devices, microchip reactors and biosensors among others. Formation of Laser Induced Periodic Surface Structures (LIPSS) with sub-micron periodicities is possible due to the interference between an incoming wave and a surface scattered one[1,2]. The period of LIPPS is close to the laser wavelength. In one hand, the characteristics of LIPSS preparation as compared to those of standard nanolithography methods allows to avoid clean rooms, high vacuum systems or complex stamp fabrication. On the other hand, the available LIPSS morphologies obtained are still limited. Semiconducting polymers like poly(3-alkyl thiophene) (P3HT) have been widely studied as the active layer in organic thin film transistors (OTFT) [3] and organic photovoltaic (OPV) solar cells[4]. In order to improve the interfacial area and thus device efficiency, Nanoimprint Lithography (NIL) has been employed in semiconducting polymers [4]. Here, as an alternative to NIL, we report the formation of LIPSS in P3HT thin films at two different wavelengths: 266 nm and 532 nm. The effect of laser parameters such as number of pulses and fluence will be discussed. By optimization of these parameters polymer gratings with different level of order can be obtained (Fig.1). A better absorption of P3HT at 532 nm than at 266 nm enables the preparation of rather good quality submicron structures with 532 nm period. (Fig.l). References [1] E. Rebollar, S. Pérez, J.J. Hernández, I. Martín-Fabiani, D.R. Rueda,T.A. Ezquerra,M.Castillejo, Langmuir, 27, 5596 (2011) [2] I. Martin-Fabiani, E. Rebollar, S. Pérez, D.R. Rueda, M.C. García-Gutiérrez, A. Szymczyk, Z. Roslaniec, M. Castillejo,T. A. Ezquerra, Langmuir 28, 7938 (2012) [3] A. Facchetti, Chem. Mater., 23 (3), 733 (2011) [4] F. Liu, Y. Gu, J. W. Jung,W.H. Jo, T. P. Russell1,, J. Polym. Sci. B: Polym. Phys., 15, 1018 (2012)

Figures

Figure 1: LIPPS of P3HT at 532 nm (Left) and 266 nm (Right) for optimized laser parameters.

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W-based nanowires grown by FEBID as temperature sensors for cryogenic picocalorimetry

J.J. Morales,1 M. Evangelisti,1 J. Sesé2

1 Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Departamento

de Física de la Materia Condensada, Zaragoza, 50009, Spain 2 Instituto de Nanociencia de Aragón and Laboratorio de Microscopias Avanzadas, Universidad

de Zaragoza, Zaragoza, 50018, Spain [email protected]

We have grown tungsten-based nanowires by Focused Electron Beam Induced Deposition (FEBID), using W(CO)6 as the precursor gas. Electronic transport measurements show that the resistance of the nanowires depends strongly on temperature below 4.2 K (see, e.g., Fig. 1), suggesting their potential application as thermometers. This allowed us to improve the Si membrane-based MEMS calorimeters, which are under development in our group. These devices are designed for AC calorimetry, viz., an AC current is applied to the heater and the AC temperature response in the thermometer is analyzed thereof. The amplitude of this oscillation is inversely proportional to the heat capacity of the sample [1]. The quality and sensitivity of the measurements strongly depend on the characteristics of the thermometer, making this element as the most important component of the device. Here, we present a new generation of calorimeters that we have developed by implementing a W-based nanowire as the temperature sensor (Fig. 2). The Si membrane size is 500 x 500 x 2 μ3. We sputter Cu-Ni for fabricating the heater. The reduced size of all components result in the significantly small addenda of c.a. 10 pJ/K at 4 K. This sensitivity permits measuring the heat capacity of sub-μg samples. Our devices are versatile and can be used in different platforms. The electronic set-up and software for the automatic data acquisition have been implemented in-house and tested in a Quantum Design PPMS, equipped with the 3He option, and in an 3He/4He dilution refrigerator, down to sub-Kelvin temperatures. References [1] J.-L. Garden, H. Guillou, a. F. Lopeandia, J. Richard, J.-S. Heron, G. M. Souche, F. R.

Ong, B. Vianay, and O. Bourgeois, “Thermodynamics of small systems by nanocalorimetry: From physical to biological nano-objects,” Thermochim. Acta, vol. 492, no. 1–2, pp. 16–28, Aug. 2009.

Figures

Figure 1. Electrical resistivity as a function of temperature for a NbN thin film, in which we have implemented a W-nanowire thermometer (inset). Figure 2. Design of the new

picocalorimeter, highlighting the deposition area of the W-nanowire.

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Transversal orientation of the magnetization in Cu/Ni/Cu patterned rings and lines

E. C. Corredor1, 3, D. Coffey2,3, J. I. Arnaudas1,3 and M. Ciria2,3

1Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain

2Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas, Zaragoza, Spain

3Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain [email protected]

Nanostructures with high-symmetry geometries, as rings and lines, have a remarkable importance for the future development of technological applications due to the fact that they present stable magnetic states that can be further tuned by an appropriate selection of the structure's dimensions [1]. In this work, rings with external diameter of 3 μm and linewidth between 200 nm and 1200 nm, and lines with linewidth between 250 nm and 1200 nm, were both fabricated by focused ion beam and electron beam lithographies from a Cu/Ni (14nm)/Cu multilayer [2]. The magnetic domain structure was visualized by using magnetic force microscopy (MFM). A domain structure with transverse magnetization was observed in both kinds of systems, with magnetic domains along the radial direction for the case of the rings, or transverse to the line direction in the other case (see Fig. 1). This fact is explained by the existence of transverse magnetoelastic anisotropy in patterned Ni films [3], due to an in-plane anisotropic relaxation of the strain existing in the continuous film. Rings and lines having widths larger than 1000 nm show out-of-plane domains suggesting that the radial strain relaxation decreases as the width increases. Micromagnetic calculations on narrow-linewidth structures indicate that the domain-wall structure consists of elliptical Bloch lines [4]. References [1] M. Kläui, C A F Vaz, L. Lopez-Diaz and J A C Bland, J. Phys.: Condens. Matter 15, R985–R1023 (2003). [2] E. C. Corredor, D. Coffey, J. I. Arnaudas, C. A. Ross, and M. Ciria, Eur. Phys J. B 86, 134 (2013). [3] M. Ciria, F. J. Castaño, J. L. Diez-Ferrer, J. I. Arnaudas, B. G. Ng, R. C. O'Handley, and C. A. Ross, Phys Rev. B 80, 094417 (2009). [4] E. C. Corredor, D. Coffey, J.I. Arnaudas, J. Aisa, C. A. Ross, M. Ciria, Phys. Rev. B 88, 054418 (2013). Figures

Figure 1: MFM images of Cu/Ni(14nm)/Cu patterned structures. (a) A ring with 3 μm external diameter and

linewidth of 250 nm. (b) Line with 300 nm width.

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Arrays of densely-packed isolated nanowires by Focused Beam

Induced Deposition plus Ar+ milling

José María De Teresa1,2,3, R. Córdoba2,3

1 Instituto de Ciencia de Materiales de Aragón, Facultad de Ciencias, Universidad de Zaragoza-CSIC, E-50009, Zaragoza, Spain.

2 Departamento de Física de la Materia Condensada, Universidad de Zaragoza, E-50009, Zaragoza, Spain. 3 Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA),

Universidad de Zaragoza, Campus Río Ebro, E-50018, Zaragoza, Spain.

[email protected]

Over the past decade there has been a significant effort in the field of focused beam induced deposition to demonstrate that high resolutions (in the order of only a few nanometers) can be achieved [1, 2]. But until now the functionality of the deposits at these small scales has received little attention. Our target is to explore novel routes to achieve densely-packed structures based on functional materials grown by focused beam induced deposition. The isolation of such small magnetic or superconducting structures grown by focused beam induced deposition is very important for the exhibited properties, as we have previously demonstrated [3]. Here, we show the growth of arrays of densely-packed isolated nanowires based on the use of Focused Beam Induced Deposition plus Ar+ milling. The growth strategy presented allows the creation of films showing thickness modulation with periodicity determined by the beam scan pitch. The subsequent Ar+ milling translates such modulation into an array of isolated nanowires. This approach has been applied to grow arrays of W-based nanowires by Focused Ion Beam Induced Deposition, using W(CO)6 precursor, and Co nanowires by Focused Electron Beam Induced Deposition, using Co2(CO)8 precursor. We have achieved linear densities up to 2.5 x 107 nanowires/cm (one nanowire every 40 nm) [4]. References [1] L. Serrano-Ramon et al., ACS Nano 5, 7781 (2011) [2] A. Fernández-Pacheco et al. Sci Rep 3, 1492 (2013) [3] R. Córdoba et al., Nature Communications 4, 1437 (2013) [4] J. M. De Teresa and R. Córdoba, ACS Nano 8, 3788 (2014) Figures

Figure 1: Strategy developed to create highly-dense isolated cobalt nanowires: first, modulated deposits are grown by tuning the pitch of the beam scan in the “y” direction and optimizing other growth parameters;

second, an Ar+ milling process transfers such modulation into an array of isolated nanowires [4].

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Focused Electron and Focused Ion Beam Induced Processing as tools for nanodevice fabrication: from basics to prototype fabrication and testing

Jordi Sama1, Juan Daniel Prades1, Olga Casals1, Francisco Hernandez-Ramirez1,2,

Sven Barth3, Isabel Gracia4, Carles Cané4, Albert Romano-Rodriguez1

1 Universitat de Barcelona (UB), MIND-IN2UB-Departament d’Electrònica, c/Martí i Franquès, 1, 08028 Barcelona, Spain

2 Institut de Recerca en Energia de Catalunya (IREC), c/Jardins de les Dones de Negre, 1, 08930 Sant Adrià de Besòs, Spain

3 Technical University Vienna, Institute of Materials Chemistry, Getreidemarkt 9/BC/02, 1060 Vienna, Austria

4 Consejo Superior de Investigaciones Científicas (CSIC), Institut de Microelectrònica de Barcelona-Centro Nacional de Microelectrónica, Campus UAB, 08193 Bellaterra, Spain

e-mail: [email protected]

In the last two decades, the development, fabrication and characterisation of 1D nanostructures have received large efforts because of their new and improved properties derived from their reduced size and well controlled chemical characteristics [1]. The extraction of electrical parameters of such materials and their manipulation, positioning and contacting for the fabrication of nanodevices is still quite scarce.

In this work we report the activity carried out on the development, fabrication and test of advanced gas nanosensors prototypes based on individual SnO2 nanowire chemiresistors, whose principle of operation is the resistance change due to the adsorption of gas [2]. Vapor-liquid-solid (VLS) growth method was employed, leading to defect-free monocrystalline nanowires [3]. The fabrication of the nanodevices involved dispersion on top of substrates with photolithographically prepatterned microelectrodes and contact fabrication using Focused Electron- and Focused Ion Beam Induced Processing [4] (Figure 1). The characterization of these chemiresistors towards different oxidizing and reducing gases at their usual operation temperatures (between 150 and 325ºC) has been carried out and the nanodevices have shown their sensitivity to the gases and their reliable operation, even up to long times. When operated as chemiresistors, the measurement of the resistance is obtained from the current-voltage characteristics, which causes Joule heating of the nanowire and that can be positively used for achieving the operation temperature local when using stabilized currents (Figure 2), giving rise to ultralow power consumption devices that only require few W for their heating and readout [5].

References [1] M. Law, J. Goldberger, P. Yang, Annu. Rev. Mater. Res. 34, 151 (2004). [2] P.T. Moseley. B.C. Tofield, Solid State Gas Sensors, Adam Hilger, Bristol, 1987. [3] S. Mathur, S. Barth, H. Shen et al, Small 1, 713 (2005). [4] F. Hernandez-Ramirez, A. Tarancon, O. Casals, et al, Nanotechnol. 17, 5577 (2006). [5] J. D. Prades, R. Jimenez-Diaz, F. Hernandez-Ramirez, et al, Appl. Phys. Lett. 93, 123110 (2008). Figures

Figure 1: SnO2 nanowire (centre) contacted byFEBIP and FIBIP deposition of Pt

Figure 2: Response of a nanowire to NO2 pulses when heated with external heater vs heated by Joule effect.

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Tailoring of nanostructure in thin films through control of

self-assembled block-copolymers morphology by small guest molecules.

A. Álvarez-Fernández1, F. Valdés-Bango 2,3, F. J. García-Alonso1,3, M. Vélez 2, J. I. Martín 2,3 J. M. Alameda2,3

1 Depto. Química Orgánica e Inorgánica, Universidad de Oviedo, 33006 Oviedo, Spain.

2 Depto. Física, Universidad de Oviedo, 33007 Oviedo, Spain. 3 CINN (CSIC - Universidad de Oviedo - Principado de Asturias), Llanera, Asturias, Spain.

Recently, block copolymers (BCPs) have attracted much attention as a powerful and very promising tool for the fabrication of nanoscale ordered structures. Amphiphilic BCPs can self-assemble into various nanostructures such as spherical/cylindrical micelles, lamella phases, or vesicle membranes depending on different factors. BCPs in thin films can be utilized to realize various potential applications, including nanolithography [1], high density array for information storage media [2], photonic band-gap materials [3], or templates to synthesize inorganic materials [4] in nanotechnology. On the other hand, a strategy that combines supramolecular chemistry with BCPs self-assembly has been developed and provides a simple and powerful technique for controlling the morphology and size of these nanostructures in thin films. In our case, spin-coating toluene solutions of PS-b-P4VP containing acetic acid leads to micellar thin films, where the micelles contain acetic acid as a guest molecule. The size and the intermicellar distances can be conveniently modified altering the copolymer concentration, the amount of the organic acid in the starting solutions and the spin coating conditions. For a 10:1 CH3COOH:P4VP ratio, even the morphology can be tuned from micelles to cylinder films increasing copolymer concentration. Surface reconstruction of micellar and cylindrical films using EtOH to extract the acetic acid guest molecules produces ring-shaped copolymer nanoporous films and mushroom-like structured films, respectively. Finally, we have also obtained metallic nanoparticles by incorporating metallic salts with a chemical affinity for the P4VP domains. References [1] C.J. Hawker, T.P. Russell, MRS Bull. 30 952 (2005). [2] W. Lee, H. Han, A. Lotnyk, M.A. Schubert, S. Senz, M. Alexe, D. Hesse, S. Baik, U. Gösele Nat, Nanotechnology 3 402 (2008). [3] A.C. Edrington, A.M. Urbas, P. DeRege, C.X. Chen, T.M. Swager, N. Hadjichristidis, M. Xenidou, L.J. Fetters, J.D. Joannopoulos, Y. Fink, E.L. Thomas, Adv. Mater. 13 421 (2001). [4] D.H. Lee, S. Park, W. Gu, T.P. Russell, ACS Nano 5 1207 (2011).

Figures

Figure 1: Atomic Force Microscope images of different structures obtained by PS-P4VP: Micelles with acetic acid as a guest molecule, with different size and

intermicellar distance (A, B); Vertical cylinders (C) and nanoporous ring-shaped film obtained from micelles with different intermicellar distance (D,E)

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List of Participants

Alberto Alvarez Fernandez University of Oviedo [email protected]

Libe Arzubiaga CIC nanoGUNE [email protected]

Cristina Blanco Roldán Univ. Oviedo & CINN (CSIC) [email protected]

Javier Bravo Fundación CETENA [email protected]

Laura Casado INA/LMA (Univ. Zaragoza) [email protected]

Vito Clericò University of Salamanca [email protected]

Ana Conde Rubio University of Barcelona [email protected]

Edna C. Corredor Vega INA (Univ. Zaragoza) [email protected]

José María De Teresa CSIC-University of Zaragoza [email protected]

Javier del Valle Granda Univ. Complutense Madrid [email protected]

Enrique Díez University of Salamanca [email protected]

Francisco Miguel Espinosa Barea Inst. Ciencia de Materiales de Madrid-CSIC [email protected]

Laura Evangelio Araujo IMB-CNM (CSIC) [email protected]

Tiberio Ezquerra Sanz IEM-CSIC [email protected]

Mercedes Fatás INA/LMA (Univ. Zaragoza) [email protected]

Amalio Fernández-Pacheco University of Cambridge [email protected]

Albert Fert CNRS/Thales [email protected]

Francisco Freire Fernández Raith GmbH & INA (Univ. Zaragoza) [email protected]

Fernando Gálvez Alonso Univ. Complutense Madrid [email protected]

Ismael García Serrano INA (Univ. Zaragoza) [email protected]

Ramón Bernardo Gavito Univ. Autónoma Madrid [email protected]

Klaus Gieb FAU Erlangen [email protected]

Peter Gnauk Carl Zeiss [email protected]

Phillippe Godignon IMB-CNM (CSIC) [email protected]

Maite Goiriena Goikoetxea Basque Center for Materials (BCMaterials) [email protected]

Federico Golmar Centro de Micro y Nano Electrónica - INTI [email protected]

Juan Carlos González Rosillo ICMAB/CSIC [email protected]

Ana Isabel Gracia Lostao INA/LMA (Univ. Zaragoza) [email protected]

102


Rainer Hillenbrand CIC nanoGUNE [email protected]

Luis Hueso CIC nanoGUNE [email protected]

Ricardo Ibarra INA/LMA (Univ. Zaragoza) [email protected]

Miren Isasa CIC nanoGUNE [email protected]

David Jiménez Carl Zeiss [email protected]

Jordi Llobet Sixto IMB-CNM (CSIC) [email protected]

Cristina López López Univ. Politécnica Madrid [email protected]

Lorena Marín Mercado INA (Univ. Zaragoza) [email protected]

José Ignacio Martín Univ.Oviedo & CINN (CSIC) [email protected]

Elena Martinez Solanas University of Zaragoza [email protected]

Santos Merino IK4-Tekniker [email protected]

Andrea Migliorini Univ. Politécnica Madrid [email protected]

Juan José Morales Chaves ICMA/CSIC [email protected]

Vincent Morin Raith GmbH [email protected]

Jana Muenchenberger Raith GmbH [email protected]

Aurora Nogales IEM-CSIC [email protected]

Mario Alberto Oliveira Ribeiro CIC nanoGUNE [email protected]

Deitze Otaduy IK4-TEKNIKER [email protected]

Mª Carmen Pallarés Matute INA/LMA (Univ. Zaragoza) [email protected]

Matteo Pancaldi CIC nanoGUNE [email protected]

Francesc Perez-Murano IMB-CNM (CSIC) [email protected]

José Luis Prieto Univ. Politécnica Madrid [email protected]

Ivo Rangelow Technische Universität Ilmenau [email protected]

Andreas Remscheid Raith GmbH [email protected]

Aritz Retolaza Muñoa IK4-TEKNIKER [email protected]

Isabel Rivas INA/LMA (Univ. Zaragoza) [email protected]

Álvaro Rodríguez Rodríguez IEM-CSIC [email protected]

Manuel Rodríguez Osorio Instituto IMDEA Nanociencia [email protected]

Isabel Rodríguez Instituto IMDEA Nanociencia [email protected]

Albert Romano-Rodriguez University of Barcelona [email protected]

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Luis Ruiz-Valdepeñas Univ. Complutense Madrid [email protected]

Yu Kyoung Ryu Cho Inst. Ciencia de Materiales de Madrid-CSIC [email protected]

Edurne Sagasta Urrutia CIC nanoGUNE [email protected]

Susana Sangiao Barral INA (Univ. Zaragoza) [email protected]

Soraya Sangiao ARAID / INA/LMA (Univ. Zaragoza) [email protected]

Ulrich Seitz FAU Erlangen [email protected]

Inés Serrano Esparza ICMA [email protected]

Luis Serrano CEMES-CNRS [email protected]

Javier Sesé INA (Univ. Zaragoza) [email protected]

Teobaldo Torres LMA/INA (Univ. Zaragoza) [email protected]

Oihana Txoperena Matxikote CIC nanoGUNE [email protected]

Fernando Valdés-Bango García Univ. Oviedo & CINN (CSIC) [email protected]

Ruben Valero Velilla INA/LMA (Univ. Zaragoza) [email protected]

Jose Luis Vicent Univ. Complutense Madrid [email protected]

Felipe Viela Instituto IMDEA Nanociencia [email protected]

Laia Vilar CETEMMSA Technological Center [email protected]

Estitxu Villamor CIC nanoGUNE [email protected]

Wenjing Yan CIC nanoGUNE [email protected]

Hanbin Zheng Centre de Recherche Paul Pascal/CNRS [email protected]

Documents

6th Spanish Workshop in - digital.csic.es