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NANOCOMPUTING BY FIELD-COUPLED NANOMAGNETS. AUTHORS : Gyorgy Csaba Alexandra Imre Gary H. Bernstein Wolfang Porod (fellow IEEE) Vitali Metlushko REFERENCE : IEEE TRANSACTION ON NANOTECHNOLOGY, VOL 1, NO. 4, DECEMBER 2002. REPORT EDITED BY : Andrea Anzalone Marco Scagno CIRCLE :

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nanocomputing by field coupled nanomagnets
NANOCOMPUTING BY FIELD-COUPLED NANOMAGNETS
  • AUTHORS:

Gyorgy Csaba

Alexandra Imre

Gary H. Bernstein

Wolfang Porod (fellow IEEE)

Vitali Metlushko

  • REFERENCE :

IEEE TRANSACTION ON NANOTECHNOLOGY, VOL 1, NO. 4, DECEMBER 2002

slide2

REPORT EDITED BY :

Andrea Anzalone

Marco Scagno

  • CIRCLE :

course of:

NANOELETTRONICA 1

professor:

E. DIZITTI

summary
SUMMARY
  • INTRODUCTION
  • SPICE MODEL FOR SIMULATION
  • NANOMAGNETIC WIRE
  • MAGNETIC MAJORITY GATE
  • FINAL REMARKS
introduction
INTRODUCTION

Achievements:

from

thin magnetic film technologies

to

patterned magnetic media on the deep

submicron and nanoscale

slide5

INTRODUCTION

Basic structure:

use of individual ferromagnetic dots

ONE DOT ONE BIT OF INFORMATION

slide6

INTRODUCTION

ADVANTAGES:

  • Lower energy dissipation
  • Higher speed
  • Larger storage density
slide7

INTRODUCTION

TARGET DEVICES :

STORAGE :

Hard Disk Drives (HDDs)

Magnetic Random Access Memories (MRAM)

NANOMAGNETIC WIRES

MAGNETIC MAJORITY GATES

( “programmable” elementary logic devices )

slide9

SPICE MODEL FOR SIMULATION

Presence of dipolar interaction between neighbouring magnetic particles:

THIS EFFECT IS :

a disadvantage for HDDs and MRAM

( limit to packing density of dots)

an advantage for nanomagnetic wires and magnetic majority gates

slide10

SPICE MODEL FOR SIMULATION

We need models for:

  • each single micromagnetic dot
  • interaction dot to dot
slide11

SPICE MODEL FOR SIMULATION

1) General mathematical approach :

use of the well-established theory of micromagnetics

  • PROBLEM : this theory is:
          • TOO COMPLEX
          • COMPUTATIONALLY INTENSIVE
slide12

SPICE MODEL FOR SIMULATION

2) Use of SPICE macromodels :

based on single-domain approximation ( SDA )

THIS IS A NEW, INNOVATIVE

SOLUTION

useful to design large dots arrays

slide13

SPICE MODEL FOR SIMULATION

ADVANTAGES:

  • more efficient simulations
  • very powerful possibility to design nanomagnetic structures integrated in microelectronic circuits
slide16

NANOMAGNETIC WIRE

WHAT IS IT ?

  • It is a line of coupled nanomagnets
slide17

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 state.

slide18

NANOMAGNETIC WIRE

Digital information is represented by the vertical component of the magnetization (mz)

  • mz = 1 if BIT = ‘1’
  • mz = -1 if BIT = ‘0’
slide19

NANOMAGNETIC WIRE

An external magnetic field is applied to drive the dots from an arbitrary initial state to the ordered final state

slide20

NANOMAGNETIC WIRE

STANDARD STEPS FOR A NANOWIRE :

  • 1) we considered a general initial configuration
slide21

NANOMAGNETIC WIRE

STANDARD STEPS FOR A NANOWIRE :

  • 2) an initial strong external field erase the “memory” of the initial state:
  • mz = 0 for each dot
slide22

NANOMAGNETIC WIRE

STANDARD STEPS FOR A NANOWIRE :

  • 3) an input current influence the magnetization of the input dot
slide23

NANOMAGNETIC WIRE

STANDARD STEPS FOR A NANOWIRE :

  • 4) the external field is adiabatically lowered and the input signal can propagate through the structure
slide24

FIG 5 - SPICE simulation of the nanowire. The driver current and the mz components are shown . The phases (a), (b), (c), (d), corresponds to schematics of FIG 4 . The dashed line is the pump field

slide25

MAGNETIC MAJORITY GATE

IT IS THE BASIC LOGIC BUILDING BLOCK OF NANOMAGNETIC CIRCUITS

slide26

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 6

slide27

MAGNETIC MAJORITY GATE

IT HAS:

  • 3 inputs
  • 1 output
  • The device is clocked by an external pumping field in a similar way to the nanowires
slide28

MAGNETIC MAJORITY GATE

THE INPUTS HAVE NO PREDEFINED FUCTIONS:

if we force one of them to ‘1’ the device realizes a logic NOR function between the other two inputs and the output

if one input is ‘0’ the gate computes the NANDfunction

slide29

FIG 7 - SPICE simulation of the magnetic majority gate. The currents correspond to the perpendicular magnetization of the dots. The dashed line is the pump field.

slide30

FINAL REMARKS

Need of input wires and output sensors only at the interface of the device:

WHITIN IT EACH SINGLE BASIC MODULE CAN BE CONNECTED USING NANOWIRES

  • High integration density:
  • above TERABIT / inch²
slide31

FINAL REMARKS

If only quasi-static behaviour is of interest the dinamic circuit model can be replaced by its non-linear static model:

IT DEPENDS ON GEOMETRIC PARAMETERS :

High pliability for the models

  • USE OF NANOMAGNETICS ARRAYS TO SIMULATE BEHAVIOUR OF GENERAL NON LINEAR CIRCUITS
slide32

FINAL REMARKS

We have seen that a magnetic majority gates can perform basic logic functions ( NAND & NOR ):

we can suppose to use more gates (connected with nanowires) to realize any kind of boolean function and more in general to manage signal-processing tasks

slide33

FINAL REMARKS

PROMISING APPLICATIONS FOR THE FUTURE:

  • Intelligent magnetic field sensors
  • Processing-in-memory type architectures
  • Complex signal-processing units
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