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
Majority Spin Minority Spin
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
Majority Spin Minority Spin
E
DOS
nnN
EF
Majority Spin Minority Spin
E
DOS
nn
EF
Majority Spin Minority Spin
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
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
Dziękuje za uwagę!