NANOCOMPUTING BY FIELD-COUPLED NANOMAGNETS n AUTHORS : Gyorgy Csaba Alexandra Imre Gary H. Bernstein Wolfang Porod (fellow IEEE) Vitali Metlushko n REFERENCE.

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


Basic structure:Basic structure:

use of individual ferromagnetic dotsuse of individual ferromagnetic dots

ONE DOT ONE BIT OF INFORMATIONONE DOT ONE BIT OF INFORMATION


ADVANTAGES:ADVANTAGES:

• Lower energy dissipationLower energy dissipation

• Higher speedHigher speed

• Larger storage density Larger storage density


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


We need models for:We need models for:

• each single micromagnetic doteach single micromagnetic dot

• interaction dot to dot interaction dot to dot


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


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


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.


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’


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


STANDARD STEPS FOR A NANOWIRE : STANDARD STEPS FOR A NANOWIRE :

1) we considered a general initial 1) we considered a general initial configuration configuration



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



3) an input current influence the 3) an input current influence the magnetization of the input dot magnetization of the input dot



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


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


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


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


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


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

NANOCOMPUTING BY FIELD-COUPLED NANOMAGNETS n AUTHORS : Gyorgy Csaba Alexandra Imre Gary H. Bernstein Wolfang Porod (fellow IEEE) Vitali Metlushko n REFERENCE.

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