SpinFET Raja Shekar Baddula – 134366001

Sreejith K P – 133076005

Titto Thomas – 133079015

Nandakumar S R - 133070053

Need of Nanostructure device

Spin of a electron S = ħσ/2

Magnetic moment of a electron µspin = -gµBS/ ħ

σ = Pauli spin operator

µB = Bohr magnetron (eħ/2m)

Miniaturization Problems

Power dissipation

Short channel effects

Quantum mechanical

effects

ballistic

tunneling

http://www.nims.go.jp/apfim/SpinFET.html

Spin FET

EE733 : SpinFET 2

Atomic case

In Electron rest frame

Amperes' law

Heterojunction:

In analogy with the atomic

case Rashba S-O term

0 0( )eff nucleusB v E

2( )B

S O spin eff

g SE B v E

hc

2( )

2

BS O

gH p V

mc

ˆdV

V zdz

2[ ( )]

2

BS O

g dVH p z

mc dz

2[ ( )]

2

BS O

g dVH z p

mc dz

[ ( )]S OH z ph

2 21( ) ( )

2x y x y y xH p p p p

m h

, ,

y

k x k

k

k

, ,

xk y k

k

k

, , 0k z k

Spin-Orbit interaction

0

24

j rB

r

j Zev

2

0

ˆ

4nucleus

Ze rE

r

AlGaAs

InGaAs

EE733 : SpinFET 3

EE733 : SpinFET 4

RA: Resistance in the antiparallel configuration

RP: Resistance in the parallel configuration

Giant magnetoresistance (GMR)

http://www.aist.go.jp/aist_e/latest_research/2004/20041124/20041124.html

http://www.nims.go.jp/apfim/halfmetal.html

http://www.directvacuum.com/spin.asp

Origin of GMR

Parallel Antiparallel

Mott Model

Different resistivities

Scattering is :

Strong for electrons with spin antiparallel to the magnetization direction

Weak for electrons with spin parallel to the magnetization direction

EE733 : SpinFET 5

H. Ehrenreich and F. Spaepen, Academic Press, 2001, Vol. 56 pp.113-237

http://physics.unl.edu/tsymbal/reference/giant_magnetoresistance/origin_of_gmr.shtml

SpinFET : Structure & Working

EE733 : SpinFET 6

Electron spin photon polarization

Supriyo Datta & Biswajit Das, Electronic analog of the eiectro-optic modulator, APL ,1989

http://nanohub.org/resources/11128

EE733 : SpinFET 7

Structure & Working of spinFET

Supriyo Datta & Biswajit Das, Electronic analog of the eiectro-optic modulator, APL ,1989

Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010

http://nanohub.org/resources/11128

EE733 : SpinFET 8

=

Spin Injection Source(polarizer) and drain(analyzer) made of

ferromagnetic material(Fe).

Conditions with the polarizer (source) and analyzer

(drain) magnetizations parallel or antiparallel, resulting

in relatively high or low spin-dependent voltages at the

detector.

Conductance(G) = 𝑞2𝐷/𝑡.

Supriyo Datta & Biswajit Das, Electronic analog of the eiectro-optic modulator, APL ,1989

Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010

http://nanohub.org/resources/11128

EE733 : SpinFET 9

2DEGs in narrow band gap semiconductor

Ballistic tranport

Avoid spin relaxation[1]

Elliot Yafet

D'yakonov-Perl

Bir-Aronov-Pikus

[1] J. Fabian and S. Das Sarma, Spin relaxation of conduction electrons, 1993

[2] Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010

[2]

EE733 : SpinFET 10

Channel Requirements

[1] J. Nitta, F. E. Meijer, and H. Takayanagi, Spin-interference device, 1999

[2] Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010

[2]

Applied potential controls

the polarization of the

electron

Aharonov – Bohm

Experiment

Conductance

variation

Phase difference in the

wave vector

[1]

∆𝜽 = 𝟐 𝒎∗𝜼𝒍

ћ𝟐

EE733 : SpinFET 11

Electrostatic control of spin

Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010

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Gate control of the channel

J. Schliemann, J. C. Egues, and D. Loss, Nonballistic spin-field-effect transistor, 2003

[1] Satoshi Sugahara and Junsaku Nitta, Spin-Transistor Electronics: An Overview and Outlook, 2010

[1]

Scattering tolerent

Dresselhaus spin-orbit

coupling

Making both the

coefficients equal

EE733 : SpinFET 13

Non-ballistic SpinFET

[1] D. M. Gvozdie, U. Ekenberg, and I. Thylen, Comparison of performance of spin transistors with conventional transistors, 2005

[2] J. Wan, M. Cahay, and S. Bandyopadhyay, Proposal for a dual-gate spin field effect transistor: A device with very small

switching voltage and a large ON to OFF conductance ratio, 2008

Improvements

Holes as carriers

Strain engineering to shift the hole subbands

Modified device structure

Gate control hinderance

Fano resonance

Ramsauer resonance

Dual gate as an option

[1]

[2]

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SpinFET improvemts

Spintronics so far..

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Discovered by Albert Fert

and Peter Gruenberg

independently in 1988.

IBM researcher Stuart Parkin

created hard disk read

heads, which tremendously

improved data storage and

speed.

Nobel prize for GMR in

2007.

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Giant Magneto-Resistance (GMR)

MRAM

Non-volatile

Lower power consumption

than a DRAM

Write power only slightly

greater than read.

Slightly lower performance

than SRAM

Viewed as a universal

memory element.

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Memory Applications

Depending on the relative direction of magnetization of

Free electrode relative to the Fixed magnetization

electrode the channel will provide a low/high resistance .

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SpinFET based Memory

AND Logic NAND Logic

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Magnetoelectric Spin-FET for Memory, Logic,and Amplifier Applications, S. G. Tan et al., 2005

Logic Applications

A family of silicon-based semiconductors that exhibit

magnetic properties has been discovered in 2004.

A team of Princeton scientists has turned semiconductors into

magnets by the precise placement of metal atoms within a

material from which chips are made in 2006.

Scientists prove the existence of a spin battery.

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Things that gives hope..

Thank You

EE733 : SpinFET 21