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Oral presentation made at EUROMAT 2013. Describes the work done about a magnetic sensor based on DW movement. The sensors tracks the movement of a DW using anisotropic magnetoresistance. DW dynamics can be affected by externar magnetic fields like the ones created by magnetic nanobeads.
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Magnetic pinning geometry for sensing with magnetic domains walls
Héctor Corte-León1, Vahid Nabaei2,3, Alessandra Manzin2, Jon Fletcher1, Patryck Kryzstecko4, Hans Schumacher4, and Olga Kazakova1
1National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK.2Istituto Nazionale di Ricerca Metrologica (INRIM), Torino, I-10135, Italy3Dipartimento Energia, Politecnico di Torino, Torino, I-10129, Italy4Physikalisch-Technische Bundesanstalt, Braunschweig, D-38116, Germany
Project motivation and objectives Design and fabrication Identification of stable states Electrical transport
State space Conclusion
Project motivation and objectives Design and fabrication Identification of stable states Electrical transport
State space Conclusion
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Project motivation and objectives
DW electronics
Magnetization carries the information.
Practically no heating.
Very stable states.
Simpler designs
D.A. Allwood, G. Xiong, C. C. Faulkner, D. Atkinson, D. Petit, R. P. Cowburn, Science 309, 1688 (2005)
L. Thomas, S-H. Yang, K-S. Ryu, B. hughes, C. Rettner, D-S. Wang, C-H Tsai, K-H. Shen, S. Parkin, IEDM, 24.2 (2011)
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Project motivation and objectives
P. Vavassori, Donolato et al, Appl. Phys. Lett. 93, 203502 (2008)
Biosensors and manipulators
Nanobead transport and detection.
Cell manipulation.
Standarization needed.
E. Rapoport, Appl. Phys. Lett. 100, 082401 (2012)
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Proposed structure for nanobead detection
Domain Walls attract nanobeads.
Nanobead modifies local magnetic field.
Resistance is affected by Domain Wall through Anisotropic Magnetoresistance effect.
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Project motivation and objectives
Donolato et al, Nanotechnology 20 385501 (2009)
Project motivation and objectives Design and fabrication Identification of stable states Electrical transport
State space Conclusion
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Design and fabrication
L-shape nanostructure of Py (Ni20Fe80)
Si/SiO2 substrate
Pt protective layer on top of Py
Gold contacts
Project motivation and objectives. Design and fabrication. Identification of stable states. Electrical transport.
State space. Conclusion.
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Identification of stable states
Using a Magnetic Force Microscope and an electromagnetic coil we are able to trap and remove DW in the corner of the device.
Magnetic Field
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Identification of stable states 4 States were identified at zero field.
Project motivation and objectives Design and fabrication Identification of stable states Electrical transport
State space Conclusion
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Transport measurements
Anisotropic magnetoresistance.Resistance of a material depends on the interaction between
magnetization and electrical current.
R=R┴+∆Rcos2
Magnetic Material
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Transport measurements
Setup.AC current,10A.
Voltage across corner.
Measure ∆R
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Magnetic Field
Transport measurements
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B(mt)
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State space
4 stable states identified at zero field.
Device is set into one of these 4 states.
Starting with a well defined state, measure the evolution of the device when applying magnetic field in different directions.
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State space
[1,1] [-1,-1]
[-1,1] [1,-1]
[1,1][-1,-1]
[1,-1][-1,1]
[-1,1]
[-1,-1]
[1,-1][-1,1]
[1,-1]
[1,1]
[1,-1]
[-1,-1]
[-1,1]
[1,1][1,1]
[-1,1][1,-1]
[-1,-1]
57.6
57.1
57.35
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State space
1
2
23 3
4
5 ≡1
12 3
4 5≡1Res
ista
nce
()
Time (a.u.)
4
57.6
57.1
57.35
Extracted
Measured
Project motivation and objectives Design and fabrication Identification of stable states Electrical transport
State space Conclusion
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Conclusion
Domain wall pining geometry has been tested with AMR.
Stable states have been identified. Low/high resistance states correspond to
presence/absence of the domain wall. Complete state space map has been measured. Noise analysis is used for determination of the best
working parameters.
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Future experiments:Bead Detection
Focus Ion Beam and micromanipulators.
Beads placed manually one by one.
Superparamagnetic Dynal® beads.
Magnetic Nanobead experiments will quantify the sensing properties of the structure.
Thanks to everyone.
