magnetic tunnel junction (mtj) or tunnel magnetoresistance...

Magnetic Tunnel Junction (MTJ)or

Tunnel Magnetoresistance (TMR)or

Junction Magneto- Resistance (JMR)

Lecture 5

H

FM I

I

FM II

TMR = 14 % at 4.2 K

Fe/Ge/CoM. Julliere, Phys. Lett. 54A (1975)

↑↑

↑↑↑↓ −=

RRR

TMR

TMR = 18 % at 300 K

Fe/Al2O3/FeT. Miyazaki, J. Magn. Magn. Mat . 54A (1995)

TMR = 11.8 % at 295 K

CoFe/Al2O3/CoJ. S. Moodera, Phys. Rev. Lett, 74 (1995)

TMR = 20.2% at 295 K

Co/Al2O3/ Ni80 Fe20

J. S. Moodera, et al. Phys. Rev. Lett, 74 (1998)-100 -75 -50 -25 0 25 50 75 100

2

3

4

R [k

Ω]

H [kA/m]

-200 -150 -100 -50 0 50 100 150 200

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

M [T

]

H [kA/m]

History of MTJ

Streszczenie

W 1995 roku magnetyczne, metaliczne złącza tunelowe wykazywaływ temperaturze pokojowej 20 % wzrost magnetorezystancji tunelowej, w roku 2002 złącza tunelowe o strukturze zaworu spinowego wykazywały już 60% wzrost, a w roku 2004 (październik) wzrost aż 220% IBM, S.S.P. Parkin

2005 – New world record230%! Anelva & Advanced Industrial Science and Technology (AIST), Japan2006 - 472% AIS2008 – 604%

128 Mbit ⇒ 370 mV

472% AIST(2006)

Ta10/PtMn15/CoFe2.4/Ru0.7/CoFeB2.8/Alx/Ox/CoFeB3.5/Ta5 Ta10/PtMn20/CoFe2.2/Ru0.8/CoFe2.2/Alx/Ox/CoFe1.5/NiFe4/Ta5

TMR vs. RA summary Singulus Al-O

0

50

100

150

200

250

0,1 1,0 10,0 100,0 1 000,0 10 000,0RA [Ω µm²]

TMR

[%]

nat ox CAPRES

nat ox patterned

plasma ox CAPRES

plasma ox patterned

Freescale MgO_4

Anelva2006 (MgO+Mg)

Anelva2006 (MgO)

TDK2006

TMR vs. RA summary Singulus MgO

S.Yuasa, et al., Nature vol.3 December (2004), 868

S.Yuasa, et al. – Giant room temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel juctins , Nature vol.3 December (2004), 868

•The origin of giant TMR effect in single-crystal Fe(001)/ MgO(001)/Fe(001) structure (prepared by MBE) is coherent spin-polarized tunnelling, where the symmetry of electron wave functions play an important role

•The oscillations as a function of tunnel barrier thickness, indicating that coherency of the wave functions is conserved across the tunnel barrier

• The coherent TMR effect is a key to making spintronic devices with novel quantum-mechanical functions, and to developing to giga-bit scale MRAM

S.S.P. Parkin et al. – Nature vol.3 December (2004), 862

•Sputter-deposited polycrystalline MTJs grown on amorphous underlayer, but with highly oriented (100) MgO tunnel barrier and CoFe electrodes, exhibit TMR values of up to ~ 220% at RT and ~ 300% at low temperature.

•Superconducting tunnelling spectroscopy experiments indicate that the tunnelling current has a ver high spin polarization of ~ 85%.

S.S.P. Parkin et al.- Giant tunnelling magnetoresistance at room temperature with MgO(100) tunnel barriers Nature vol.3 December(2004), 868

DeBrosse J, Arndt C, Barwin C, Bette A, Gogl D, Gow E, Hoenigschmid H, Lammers S, Lamorey M, Lu Y, Maffitt T, Maloney K, Obermeyer W, Sturm A, Viehmann H, Willmott D, Wood M, Gallagher WJ, Mueller G, Sitaram AR. A 16Mb MRAM featuring bootstrapped write drivers. [Conference Paper] 2004 Symposium on VLSI Circuits. Digest of Technical Papers (IEEE Cat. No.04CH37525). Widerkehr and Associates. 2004, pp.454-7. Gaithersburg, MD, USA.

Abstract

A 16Mb Magnetic Random Access Memory (MRAM) is demonstrated in 0.18 mu m three-Cu-level CMOS with a three-level MRAM process adder. The chip, the highest density MRAM reported to date, utilizes a 1.42 mum/sup 2/ 1-Transistor 1-Magnetic Tunnel Junction (1T1MTJ) cell, measures 79mm/sup 2/ and features a *16 asynchronous SRAM-like interface. The paper describes the cell, architecture, and circuit techniques unique to multi-Mb MRAM design, including a novel bootstrapped write driver circuit. Hardware results are presented. (5 References).

News

Infineon and IBM Present World´s First 16 Mbit MRAM - Innovative Chip Design Results in Highest Density Reported to Date

2004-06-22

The increasing number of mobile applications such as smartphones and notebooks with additional multimedia features results in the need for more advanced memory chips. MRAM is a promising candidate for universal memory in high-performance and mobile computing as it is faster and consumes less power than existing technologies.

Spin Polarization, Density of States

Ferromagnetic metal (Fe)

↓↑

↓↑

+

−=

nnnn

P

Spin Polarization Density of states 3d

Ni 33 %

Co 42 %

Fe 45 %

Ni80 Fe20 48 %

Co84 Fe16 55 %

CoFeB 60%

CoFe/MgO/ 85%

Material Polarizations

Normal metal (Cu)

EF

Majority Spin Minority Spin

E

DOS

nn

)()( FF EnEn ↓↑ > )()( FF EnEn ↓↑ =

N

EF


E

DOS

nn

Tunneling in FM/I/FM junction

↓↑

↓↑

+−

=II

III nn

nnP↓↑

↓↑

+−=

IIII

IIIIII nn

nnP

III

III

M

MM

PPPP

III

TMR−

=−

=↑↓

↑↓↑↑

12

↑↑

↑↑↑↓ −=

RRR

TMR

↓↓↑↑↑↑ +∝ IIIIIIM nnnnI

↑↓↓↑↑↓ +∝ IIIIIIM nnnnI

↓I↑I

↑I ↓I

FM I (PI) FM II (PII)

Barrier

eVN

EF


E

DOS

nnN

EF


E

DOS

nn

EF


E

DOSNnn

Type of MTJsStandard junction

FM

I

FM

FM

I

FM

I

FM

Spin valve junction(SV- MTJ)

Double barrier junction

B

AF

FM

I

FM

-100 -50 0 50

-0.8

-0.4

0.0

0.4

0.8

M [T

]

H [kA/m]-200 -150 -100 -50 0 50 100 150 200

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

M [T

]

H [kA/m] -150 -100 -50 0 50

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

M [T

]

H [kA/m]

Application-Oriented Properties of S-V MTJ

• Tunnel Magnetoresistance -TMR

• Resistance area product -RxA

• Interlayer coupling field HS

• Exchange bias field HEXB

• Coercive field pinned HCPand free HCF layer

• Switching field HSF

Magnetic

Materials• I (Al-O,MgO..)

• FM (Co, CoFe, NiFe)

• AF (MnIr, PtMn, NiO)

• Buffer (Ta,Cu, NiFe)

Treatment• Annealing

• Field cooling

Preparation• Sputtering deposition

• Oxidation

SV-MTJ

Electric

Magnetic and Electric Parameters

B

AFFM II (Pinned)

IFM I (Free)

Interlayer couplingHS

Exchange couplingHEXB

HSF switching fields

-150 -100 -50 0 50

-1.2

-0.8

-0.4

0.0

0.4

0.8

1.2

M [T

]

H [kA/m]

HS

HEXBHCP

HCF

HSF

-160 -120 -80 -40 0 40 800

10

20

30

40

50

TMR

[%]

H [kA/m]

↑↑

↑↑↑↓ −=

RRR

TMR

Our experiments on SV -MTJs

A

3 6 10 30 50

Substrate Si (100)

Cu 25 nm

MnIr 12 nm

CoFe t nm

Al2O3 1.4 nm

NiFe 3 nm

Ta 5 nm

Cu 30 nm

Ta 3 nm

Au 25 nm

010 30 60 100

Substrate Si (100)

SiO2

Ta 5 nm

Cu 10 nm

Ta 5 nm

NiFe 2 nm

Cu 5 nm

MnIr 10 nm

CoFe 2.5 nm

Al2O3 1.4 nm

CoFe 2.5 nm

NiFe x nm

Ta 5 nm

B

A structure prrepared in laboratory of University BielefeldB structure prepared in laboratory of Tohoku University

10 mm

Junction

Junction

Junctions size (180×180) μm2

Effect of Annealing on TMRAs deposited Annealed

-150 -100 -50 0 50 100 1500

2

4

6

8

10

12

14

TMR = 13.4 %

TMR

[%]

H [kA/m]

100 150 200 250 300 3500

5

10

15

20

25

30

35

40

TMR

[%]

Annealing temperature (oC)

100 nm (10 sec) 100 nm (13 sec) 100 nm (16 sec) 10 nm (10 sec) 10 nm (13 sec) 10 nm (16 sec)

-120 -80 -40 0 40 80 1200

10

20

30

40

50 TMR = 48 %

TMR

[%]

H [kA/m]

10 mm

H=80 kA/m

annealing 1 hour in vacuum 10-6 hPa

MTJ systems for electrical measurements

AGH samples

Substrate Si(100)

SiO

Cu 25

IrMn 12

CoFe xAlO 1.4NiFe 3

Ta 5

Cu 30

Ta 3

Au 25

pinned

free

Substrate Si(100)

SiOTa 5

Cu 25

a b

Buffers

-100 -50 0 50 100

0

10

20

30

40

50

60

a1 b1

TMR

(%)

H (Oe)

(a1) Hs = 13.8(b1) Hs = 49.5

-1500 -1000 -500 0 500 1000 1500

0

10

20

30

40

50

60

(a1) HEXB = 618 (b1) HEXB = 920

a1 b1

TMR

(%)

H (Oe)

a1= 2.5 nmb1= 2.5 nm

TEM measurement – columnar growth of grains

Barrier quality

0 5 10 15 20 25 30 35 400

1000

2000

3000

4000

IrMn(111)

a b

Inte

nsity

[cou

nts/

sec]

ω [deg]

0

100

a) RMS = 0.3 nm b) RMS = 0.6 nm

bufferIrMn

Ta20

40

60

80a2_m - IrMn[111]

20

40

60

80b2_m - IrMn[111]

a) b)AFM

XRD – rocking curve

XRD – pole figure

Pole figure measurements

20

40

60

80a2_c - Cu[111]

20

40

60

80b2_c - Cu[111]

20

40

60

80c2_c - Cu[111]

20

40

60

80d2_c - Cu[111]

20

40

60

80a2_m - IrMn[111]

20

40

60

80b2_m - IrMn[111]

20

40

60

80c2_m - IrMn[111]

20

40

60

80d2_m - IrMn[111]

20

40

60

80a2_p - CoFe[111]

20

40

60

80b2_p - CoFe[111]

20

40

60

80c2_p - CoFe[111]

20

40

60

80d2_p - CoFe[111]

IrMn(111)

a) c)

Cu(111)

CoFe(110)

b) d)buffer:

CoFe thickness =15nm

Si(100)SiOTa 5

Cu 25Ta 5

NiFe 2Cu 5

Si(100)SiOTa 5

Cu 25Ta 5Cu 5

Si(100)SiOTa 5

Cu 25

Si(100)SiO

Cu 25

buffer

AFM measurements

Rms: 0.42 nm 0.69 nm 0.59 nm 0.51 nm

a) b) c) d)

Rms: 0.30 nm 0.61 nm 0.53 nm 0.42 nm

a) b) c) d)

IrMn

CoFeAlONiFe

Ta

buffer

IrMn

Ta

a) b) c) d)Si(100)

SiOTa 5

Cu 25Ta 5

NiFe 2Cu 5

Si(100)SiOTa 5

Cu 25Ta 5Cu 5

Si(100)SiOTa 5

Cu 25

Si(100)SiO

Cu 25

buffer:

Magnetic parameters

-500 -250 0 250 500 750 10000

10

20

30

40

50

TMR

[%]

H [Oe]

HEX HCP

AF

FM I (pinned)

I

FM II (free)

Exchange couplingHEX

Interlayer couplingHS

-20 0 20 40 600

10

20

30

40

50

TMR

[%]

H [Oe]

HS HCF

FF

SS tM

JH0μ

=PP

EXEX tM

JH0μ

=

For applications is important small Hs and HCF

Nèel coupling

CoFe

Al-O

NiFe

Ta

tf

tS

tpMp

Mf

λ

h

)22exp()]22

exp(1[)]22

exp(1[2

22

λπ

λπ

λπ

λπ Spf

f

ps

ttttMh

H −−−×

−−=

2 4 6 8 10 12 14 160

2

4

6

8

10

12 a b

HS [k

A/m

]

t CoFe [nm]

λ=50,h=0.7 nm

λ=50, h=0.4 nm

roughness induces magnetic dipoles

no interlayer coupling (HS=0) if interfaces are smooth (h=0)

roughness amplitude (h) determine the coupling strength

Domain images

Free layer reversal magnetization – NiFe 3nm

Pinned layer reversal magnetization – CoFe 15nm

a

a) b)

c) d)

Si(100)

SiOTa 5

Cu 25

Ta 5NiFe 2Cu 5

Si(100)

SiOTa 5

Cu 25

Ta 5Cu 5

Si(100)

SiOTa 5

Cu 25

Si(100)

SiO

Cu 25

IrMn 12

CoFe 15

AlO 1.4

NiFe 3

Ta 5

IrMn 12

CoFe 15

AlO 1.4

NiFe 3

Ta 5

IrMn 12

CoFe 15

AlO 1.4

NiFe 3

Ta 5

IrMn 12

CoFe 15

AlO 1.4

NiFe 3

Ta 5

dcb

a dcb

Domain crossing in free layer of MTJ

Si/Ta(5)/Cu(30)/Ta(20)/Cu(5)/MnIr(12)/CoFe(3)/AlOx(1.6)/NiFe(8)/Ta(10)

Courtesy of G.Reiss, J.Schötter, BielefeldUniversity, Germany

5o, HC1 5o, HC2

0o, HC1 0o, HC2

-5o, HC1 -5o, HC2

HC1 HC2

TMR measurements

2 4 6 8 10 12 14 160

10

20

30

40

50

a b c d

TMR

[%]

t CoFe [nm]

TMR(tCoFe)

↑↑

↑↑↑↓ −=

RRR

TMR

TMR for strong textured (b) MTJ monotonically decreases with increasing the thickness of pinned layer. For weak textured (a) MTJ, TMR decreases significantly for tCoFe> 9 nm.

Sputtering system– EMRALD II

Sputtering system University of Bielefeld

UHV sputtering system of Takahashi Lab. Tohoku Univ.

Metal depo.

Plasma Oxidation

LL１: wafer-in

LL２: BridgeReactive sputter : surface

smooth

TIMARIS: Tool status

Tool #1 – process optimization on ∅200 mm wafers since mid of March 03

Tool #2 – The Worlds 1st ∅300 mm MRAM System is Ready for Process in August 03

Multi (10) TargetModule

Oxidation / Pre-clean Module

Transport Module

Clean room

Sample

H coilsy

H coilsx

MOKE with Orthogonal Coils

Measurement tools

R-VSMMOKE

Real time image processing – hardware for Kerr microscope

PC-configuration

System memory

Chip Set

Pentium III procesor

1 GB/s

1GB/s

Graphiccard

(dualhead)

Monitor 1

Monitor 2

PCI 132

MB/s 8 bit framegraber

PCI Interface card

AGP528

MB/s

Kerr microscope

Analyzer

Polarizer

Objective

SampleMagnet

MirrorCCIR

camera

16-bits digitalcamera

M. Zoladz et al. Real time image processing during observation of the magnetic domain structures by Kerr microscopy - phys. stat. sol. (a) vol. 189, (2002), 791

monitor

monitor

PC

Spin Transfer Torque (STT)

T.Devolder ‘06

M2, m2- FL magnetic momentM1, m1- RL magnetic moment

dtdmmmH

dtdm

eff2

20

22

0

1×+×=⋅

γα

γ

( ) ( )( )122220

22

02

2

0

1 mmmMte

Jpdt

dmmmHdt

dmS

effectiveeff ××+×+×=⋅μγ

αγ

h( ) ( )( )122220

22

02

2

0

1 mmmMte

Jpdt

dmmmHdt

dmS

effectiveeff ××+×+×=⋅μγ

αγ

h

Slonczewski ‘96

STT• According to theory:

a) electrons with certain spin orientation (filtered by pinned layer) transfers magnetization direction to the free layer – favors parallel state

b) electrons with spin orientation antiparallel to the pinned layer magnetization cannot pass (bands are occupied) - they accumulate in the free layer - favors antiparallel state

D.C. Ralph, M.D. Stiles, J. Magn. Magn. Mater. 320 (2008)

Deriving the critical current

J- current density (A/m2)S-Area (m2)e- electron charge (A*s)ħ– Planck constant (J*s)

μ0Ms – Magnetization (T)Hk- Anisotropy field (A/m)V- Volume (m3)

Dimension lessefficiency factor

Energy of free layer

Dimension lessenergy loss rate

Available energy

energyVHM volumeKS =

20μ

eJS

energy surfaceh=

444 3444 21

h2202 volumeSeffeffective VMH

eIp μα ×=⎟

⎠⎞

⎜⎝⎛

Critical current

Micromagnetic switching modelling (OOMMF)Current-assisted switching Field-assisted switching

I= 7 mA, P=0.7 α=0.01 H= 796 kA/m

g yMeasurements (PIMM) [Q2]

• New collaboration with PTB in Braunschweigprof. Schumacher

• Precession ofmagnetization of thefree layer measurement

-2

0

2

-2

0

2

-2

0

2

-2

0

2

0 2 4

-2

0

2

0 2 4

-2

0

2

15 mT10 mT

4 mT 0 mT

-5 mT

a)

-10 mT

d)

b)

c)

Vol

tage

(mV

)

Vol

tage

(mV

)

e)

Time (ns)

f)

Time (ns)

( )

Serrano-Guisan et al. JPD 41 (2008)

( )ϕπτ −⋅⋅⋅⋅=− tfeAtV

t2sin

sM⋅⋅= τγα 2

MgO WEDGE• Samples with following structure (nm):Ta(5)/CuN(50)/Ta(3)/CuN(50)/Ta(3)/PtMn(16)/CoFe(2)/Ru(0.9/CoFeB(2.3)/MgO(0.6-1)/CoFeB(2.3)/Ta(10)/CuN(30)/Ru(7)

with MgO wedge sputtered in Singulus, J.WronaRA product range: 0.4 – 10 Ω μm2

0,6 0,7 0,8 0,9 1,0

0

50

100

150

200

0,0

2,5

5,0

7,5

10,0

0 2 4 6 8 10 12

0

50

100

150

200

MgO (nm)

RA

(Ohm

μm2 )

TM

R (%

)

a)TM

R (%

)

RA (Ohmμm2)

b)

BASIC CHARACTERISTICS

80

100

120

140

160

180

200

220

-200 -100 0 100 200 -2000 -1000 0 1000 2000

80

100

120

140

160

180

200

220

-0,8 -0,6 -0,4 -0,2 0,0 0,2 0,4 0,6 0,8

-10

-5

0

5

10

15

Field(Oe) R

esis

tanc

e (O

hm) a)

Field (Oe)

Res

ista

nce

(Ohm

)

b)

Cur

rent

(mA

)

Voltage (V)

c)

parallel

antiparallel

JUNCTION FABRICATION• Layer structure (nm):Ta(5)/CuN(30)/Ta(5)/PtMn(20)/CoFe(2.5)/Ru(0.8)/CoFeB(3)/MgO(1.1)/CoFeB(3)/Ta(10)/CuN(10)/Ru(7)/Au(50)• Two lithography steps

40um

0 200 400 600 800 1000 1200 1400 1600 1800 20003000

3500

4000

4500

5000

5500

6000

parti

cles

cou

nts

a. u

.

Time [s]

Mg Si Mn Co Fe Cu Ta Ru

e-beam LITOGRAPHY• Nanopillars fabricated on standard MTJ stack wafer from

Singulus A.G. company ( 0.25, 1 μm2) by J. Wrona• MTJ with MgO wedge wafer (0.03 – 0.15 μm2)

K. Rott, not published

Nanofabrication INESC-MN Lisbon

40x7050x8060x8070x10090x120100x200150x350200x450300x700400x900(in nm)

optical lithographybottom electrode

optical lithography top electrode

e-beam lithographynanopillar

MEASUREMENT SETUP• Constant voltage method – measurement of current 4 probe system• During CIMS measurement – „high” voltage switches junction,

resistance measured under low voltage

-0.002 0.000 0.002

400

500

600

700

800

900

1000

1100

-1.0 -0.5 0.0 0.5 1.0

400

500

600

700

800

900

1000

1100

-1.0 -0.5 0.0 0.5 1.0

400

500

600

700

800

900

1000

1100

400

500

600

700

800

900

1000

-200 -100 0 100 200

Res

ista

nce

(Ohm

)

Current (A)

c)

Voltage (V)

Res

ista

nce

(Ohm

)

b)

Voltage (V)

Res

ista

nce

(Ohm

)

d)

Field (Oe)

Res

ista

nce

(Ohm

)

a)

CIMS MEASUREMENTS

-0,3 -0,2 -0,1 0,0 0,1 0,2 0,3

60

80

100

120

140

-200 -100 0 100 20060

80

100

120

140

Voltage (V)

Res

ista

nce

(Ohm

)

b)

Field (Oe)

Res

ista

nce

(Ohm

)a)

-1.0 -0.5 0.0 0.5 1.0

400

500

600

700

800

900

1000

-200 -100 0 100 200

400

500

600

700

800

900

1000

Voltage (V)

Res

ista

nce

(Ohm

)

b)

Field (Oe)

Res

ista

nce

(Ohm

)

a)

Pillar switches with currents 1.7 mA and -2.4 mA (5.7 ×106 A/cm2 , -8 ×106 A/cm2) from AP to P state and from P to AP state, respectively.

Pillar switches with currents 2.2 mA and -3.75 mA (7.3 ×106 A/cm2 , 12.5 ×106 A/cm2) from AP to P state and from P to AP state, respectively

TMR loop (a) and CIMS loop (b) of MTJ with 0.71 nm (1) and 0.96 nm (2) thick MgO

H=-23 Oe

H=53 Oe

AP

AP

P

P

Ellipsis0.03 μm2

160 nm x 0.24 nm

Ellipsis0.03 μm2

160 nm x 240 nm

Surface energy

-4000 -3000 -2000 -1000 0 1000 2000 3000 4000

0,0

0,2

0,4

0,6

0,8

1,0

Kerr

sign

al [n

orm

aliz

ed]

Field [Oe]

sample 8 sample 7 sample 6 sample 5 sample 4 sample 3 sample 2 sample 1

2296MOKE major loops

-50 0 50 100 150 200 250

0,0

0,2

0,4

0,6

0,8

1,0

Ker

r sig

nal [

norm

aliz

ed]

Field [Oe]

sample 3 sample 4 sample 5 sample 6 sample 7 sample 8

2296MOKE minor loops

MOKE measurements

Applications of SV-MTJ

M-RAM

SPIN-LOGIC READ HEADS

SENSORS

SV-MTJ

SV-MTJ Based MRAM

Bit lines

Word lines

IB

IW

Writing “0”

Writing “1”

IB

Memory Cell

Reading current IR

Memory Matrix

SV-MTJ

IW

Writing - rotation of the free layer

Reading - detection of a resistance of a junction

SV- MTJ as MRAM component must fulfill requirements

- Thermal stability- Magnetic stability - Single domain like switching behaviour- Reproducibility of RxA, TMR and Asteroids

Hy/H

(0)

1

-1-1 10

0

Critical switching fields Hx , Hy (S-W) asteroid

Motorola: S.Tehrani et al. PROCEEDINGS OF THE IEEE, VOL. 91, NO. 5, MAY 2003

Features of M-RAM

- Non-volatility of FLASH with fast programming, no program endurance limitation

- Density competitive with DRAM, with no refresh- Speed competitive with SRAM - Nondestructive read- Resistance to ionization radiation- Low power consumption (current pulses)

• Single 3.3 V power supply

• Commercial temperature range (0°C to 70°C)

• Symmetrical high-speed read and write with fast access time (15, 20 or 25ns)

• Flexible data bus control — 8 bit or 16 bit access

• Equal address and chip-enable access times

• All inputs and outputs are transistor-transistor logic (TTL) compatible

• Full nonvolatile operation with 10 years minimum data retention

Motorola: S.Tehrani et al. PROCEEDINGS OF THE IEEE, VOL. 91, NO. 5, MAY 2003

SV-MTJ Based Spin Logic Gates

Siemens & Univ. Bielefeld: R. Richter et al. J. Magn.Magn. Mat. 240 (2002) 127–129

SV- MTJ as spin logic gates must fulfill requirements

- Thermal stability- Magnetic stability - Centered minor loop- Single domain like switching behaviour- Reproducibility of R, TMR

RMTJ2

Logic Inputs

Logic Output

Programing Inputs

SV-MTJs

RMTJ3

RMTJ1

RMTJ4

(+, )− IB

(+, )− IA

IS

ISVOUT

VOUT= IS(RMTJ3 + RMTJ3 – RMTJ1 – RMTJ2)

Logic Inputs MTJ 3, MTJ 4

0

2 VOUT

(0,0) (1,1)(1,0)(0,1) (0,0) (1,1)(1,0)(0,1)

MTJ 1 MTJ 2 MTJ 1 MTJ 2

NAND NOR

„1"

„0"Logi

c O

utpu

t

-2 VOUT

Features of Spin Logic Gates

- Programmable logic functions (reconfigurable computing)- Non-volatile logic inputs and outputs- Fast operation (up to 5 GHz) - Low power consumption - Compatibility to M-RAM

SV-MTJ Based Read Heads

SV-MTJ as a read sensor for high density (>100Gb/in2) must fulfill requirements

- Resistance area product (RxA) < 6 Ω-μm2

- High TMR at low RxA

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