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NANOCOMPUTING BY FIELD-NANOCOMPUTING BY FIELD-COUPLED NANOMAGNETSCOUPLED NANOMAGNETS
AUTHORSAUTHORS ::
Gyorgy CsabaGyorgy Csaba
Alexandra ImreAlexandra Imre
Gary H. BernsteinGary H. Bernstein
Wolfang Porod (fellow IEEE)Wolfang Porod (fellow IEEE)
Vitali MetlushkoVitali Metlushko
REFERENCE :REFERENCE :IEEE TRANSACTION ON NANOTECHNOLOGY, VOL 1, NO. 4, DECEMBER IEEE TRANSACTION ON NANOTECHNOLOGY, VOL 1, NO. 4, DECEMBER 20022002
REPORT EDITED BY :REPORT EDITED BY :
Andrea AnzaloneAndrea Anzalone
Marco ScagnoMarco Scagno
CIRCLE :CIRCLE :
course of:course of:
NANOELETTRONICA 1NANOELETTRONICA 1
professor:professor:E. DIZITTIE. DIZITTI
SUMMARYSUMMARY
• INTRODUCTIONINTRODUCTION
• SPICE MODEL FOR SIMULATIONSPICE MODEL FOR SIMULATION
• NANOMAGNETIC WIRENANOMAGNETIC WIRE
• MAGNETIC MAJORITY GATEMAGNETIC MAJORITY GATE
• FINAL REMARKSFINAL REMARKS
INTRODUCTIONINTRODUCTION
Achievements:Achievements:
fromfrom
thin magnetic film technologiesthin magnetic film technologies
toto
patterned magnetic media on the deep patterned magnetic media on the deep submicron and nanoscalesubmicron and nanoscale
INTRODUCTIONINTRODUCTION
Basic structure:Basic structure:
use of individual ferromagnetic dotsuse of individual ferromagnetic dots
ONE DOT ONE BIT OF INFORMATIONONE DOT ONE BIT OF INFORMATION
INTRODUCTIONINTRODUCTION
ADVANTAGES:ADVANTAGES:
• Lower energy dissipationLower energy dissipation
• Higher speedHigher speed
• Larger storage density Larger storage density
INTRODUCTIONINTRODUCTION
STORAGE :STORAGE :
Hard Disk Drives (HDDs)Hard Disk Drives (HDDs)
Magnetic Random Access Memories (MRAM)Magnetic Random Access Memories (MRAM)
NANOMAGNETIC WIRESNANOMAGNETIC WIRES
MAGNETIC MAJORITY GATESMAGNETIC MAJORITY GATES ( “programmable” elementary logic devices )( “programmable” elementary logic devices )
TARGET DEVICES :TARGET DEVICES :
FIG 1 - (a) Individual access of nanomagnets in an MRAM device (b) Field-coupled structure
SPICE MODEL FOR SPICE MODEL FOR SIMULATIONSIMULATION
Presence of dipolar interaction between Presence of dipolar interaction between neighbouring magnetic particles:neighbouring magnetic particles:
THIS EFFECT IS :THIS EFFECT IS :
a disadvantage for HDDs and MRAMa disadvantage for HDDs and MRAM( limit to packing density of dots)( limit to packing density of dots)
an advantage for nanomagnetic wires and an advantage for nanomagnetic wires and magnetic majority gatesmagnetic majority gates
SPICE MODEL FOR SPICE MODEL FOR SIMULATIONSIMULATION
We need models for:We need models for:
• each single micromagnetic doteach single micromagnetic dot
• interaction dot to dot interaction dot to dot
SPICE MODEL FOR SPICE MODEL FOR SIMULATIONSIMULATION
1) General mathematical approach : 1) General mathematical approach :
use of the well-established theory of use of the well-established theory of micromagneticsmicromagnetics
PROBLEM : this theory is:PROBLEM : this theory is:• TOO COMPLEXTOO COMPLEX
• COMPUTATIONALLY INTENSIVECOMPUTATIONALLY INTENSIVE
SPICE MODEL FOR SPICE MODEL FOR SIMULATIONSIMULATION
2) Use of SPICE macromodels : 2) Use of SPICE macromodels :
based on single-domain approximation ( SDA )based on single-domain approximation ( SDA )
THIS IS A NEW, INNOVATIVETHIS IS A NEW, INNOVATIVESOLUTIONSOLUTION
useful to design large dots arraysuseful to design large dots arrays
SPICE MODEL FOR SPICE MODEL FOR SIMULATIONSIMULATION
ADVANTAGES:ADVANTAGES:
• more efficient simulations more efficient simulations
• very powerful possibility to design very powerful possibility to design nanomagnetic structures integrated in nanomagnetic structures integrated in
microelectronic circuits microelectronic circuits
FIG 2 - Circuit blocks of two coupled nanomagnets FIG 2 - Circuit blocks of two coupled nanomagnets ii e e jj
FIG 3 - Schematic diagram of the dot-circuit. It have six inputs and three-outputsFIG 3 - Schematic diagram of the dot-circuit. It have six inputs and three-outputs
NANOMAGNETIC WIRENANOMAGNETIC WIRE
WHAT IS IT ?WHAT IS IT ?
It is a line of coupled nanomagnetsIt is a line of coupled nanomagnets
FIG 4 - Operating scheme of the nanowire. (a) Initial configuration (b) High-FIG 4 - Operating scheme of the nanowire. (a) Initial configuration (b) High-field state before and (c) after the application of the input. (d) Final ordered field state before and (c) after the application of the input. (d) Final ordered state. state.
NANOMAGNETIC WIRENANOMAGNETIC WIRE
Digital information is represented by Digital information is represented by the vertical component of the the vertical component of the magnetization (mmagnetization (mzz))
• mmzz = 1 if BIT = ‘1’ = 1 if BIT = ‘1’
• mmzz = -1 if BIT = ‘0’ = -1 if BIT = ‘0’
NANOMAGNETIC WIRENANOMAGNETIC WIRE
An external magnetic field is applied to An external magnetic field is applied to drive the dots from an arbitrary initial drive the dots from an arbitrary initial state to the ordered final state state to the ordered final state
NANOMAGNETIC WIRENANOMAGNETIC WIRE
STANDARD STEPS FOR A NANOWIRE : STANDARD STEPS FOR A NANOWIRE :
1) we considered a general initial 1) we considered a general initial configuration configuration
NANOMAGNETIC WIRENANOMAGNETIC WIRE
STANDARD STEPS FOR A NANOWIRE : STANDARD STEPS FOR A NANOWIRE :
2) an initial strong external field erase 2) an initial strong external field erase the “memory” of the initial state: the “memory” of the initial state:
mmzz = 0 for each dot = 0 for each dot
NANOMAGNETIC WIRENANOMAGNETIC WIRE
STANDARD STEPS FOR A NANOWIRE : STANDARD STEPS FOR A NANOWIRE :
3) an input current influence the 3) an input current influence the magnetization of the input dot magnetization of the input dot
NANOMAGNETIC WIRENANOMAGNETIC WIRE
STANDARD STEPS FOR A NANOWIRE : STANDARD STEPS FOR A NANOWIRE :
4) the external field is adiabatically 4) the external field is adiabatically lowered and the input signal can lowered and the input signal can propagate through the structure propagate through the structure
FIG 5 - SPICE simulation of the nanowire. The driver current and the FIG 5 - SPICE simulation of the nanowire. The driver current and the mmz z
components are shown . The phases (a), (b), (c), (d), corresponds to components are shown . The phases (a), (b), (c), (d), corresponds to schematics of FIG 4 . The dashed line is the pump fieldschematics of FIG 4 . The dashed line is the pump field
MAGNETIC MAJORITY GATEMAGNETIC MAJORITY GATE
IT IS THE BASIC LOGIC BUILDING BLOCK IT IS THE BASIC LOGIC BUILDING BLOCK OF NANOMAGNETIC CIRCUITS OF NANOMAGNETIC CIRCUITS
FIG 6 - Physical layout of the majority gate. The input dots (dot 2, 3, 4) are FIG 6 - Physical layout of the majority gate. The input dots (dot 2, 3, 4) are driven by electric wires and the result of the computation is represented by dot 6driven by electric wires and the result of the computation is represented by dot 6
MAGNETIC MAJORITY GATEMAGNETIC MAJORITY GATE
IT HAS: IT HAS: 3 inputs3 inputs 1 output 1 output
The device is clocked by an external The device is clocked by an external pumping field in a similar way to the pumping field in a similar way to the nanowires nanowires
MAGNETIC MAJORITY GATEMAGNETIC MAJORITY GATE
THE INPUTS HAVE NO PREDEFINED FUCTIONS:THE INPUTS HAVE NO PREDEFINED FUCTIONS:
if we force one of them to ‘1’ the device if we force one of them to ‘1’ the device realizes a logic NOR function between the realizes a logic NOR function between the other two inputs and the outputother two inputs and the output
if one input is ‘0’ the gate computes if one input is ‘0’ the gate computes the the NANDNAND functionfunction
FIG 7 - SPICE simulation of the magnetic majority gate. The currents FIG 7 - SPICE simulation of the magnetic majority gate. The currents correspond to the perpendicular magnetization of the dots. The dashed line is correspond to the perpendicular magnetization of the dots. The dashed line is the pump field. the pump field.
FINAL REMARKS FINAL REMARKS
Need of input wires and output sensors Need of input wires and output sensors only at the interface of the device:only at the interface of the device:
High integration density:High integration density:
above TERABIT / inchabove TERABIT / inch²²
WHITIN IT EACH SINGLE BASIC WHITIN IT EACH SINGLE BASIC MODULE CAN BE CONNECTED USING MODULE CAN BE CONNECTED USING NANOWIRESNANOWIRES
FINAL REMARKS FINAL REMARKS
If only quasi-static behaviour is of interest the If only quasi-static behaviour is of interest the dinamic circuit model can be replaced by its dinamic circuit model can be replaced by its non-linear static model:non-linear static model:
IT DEPENDS ON GEOMETRIC PARAMETERS :IT DEPENDS ON GEOMETRIC PARAMETERS :
High pliability for the models High pliability for the models
USE OF NANOMAGNETICS ARRAYS TO SIMULATE USE OF NANOMAGNETICS ARRAYS TO SIMULATE BEHAVIOUR OF GENERAL NON LINEAR CIRCUITSBEHAVIOUR OF GENERAL NON LINEAR CIRCUITS
FINAL REMARKS FINAL REMARKS
We have seen that a magnetic majority gates can We have seen that a magnetic majority gates can perform basic logic functions ( NAND & NOR ):perform basic logic functions ( NAND & NOR ):
we can suppose to use more gates we can suppose to use more gates (connected with nanowires) to realize any (connected with nanowires) to realize any kind of boolean function and more in kind of boolean function and more in general to manage signal-processing general to manage signal-processing taskstasks
FINAL REMARKS FINAL REMARKS
PROMISING APPLICATIONS FOR THE FUTUREPROMISING APPLICATIONS FOR THE FUTURE::
• Intelligent magnetic field sensorsIntelligent magnetic field sensors
• Processing-in-memory type architecturesProcessing-in-memory type architectures
• Complex signal-processing unitsComplex signal-processing units