Upload
sunila
View
45
Download
2
Embed Size (px)
DESCRIPTION
Properties and Fabricating Technique of Tunneling Magnetoresistance. Reporter : Kuo-Ming Wu Day : 2006/04/08. Outline. Development of Spintronics Tunneling Magnetoresistance Spin Torque Transfer Conclusion. Development of Spintronics. Spin elec tronic : Spintronics. - PowerPoint PPT Presentation
Citation preview
Properties and Fabricating Technique
of Tunneling Magnetoresistance
Reporter : Kuo-Ming WuDay : 2006/04/08
Outline
Development of Spintronics
Tunneling Magnetoresistance
Spin Torque Transfer
Conclusion
Development of Spintronics
Spin electronic : Spintronics
The spin induced ferromagnetic phenomena has a large application valuation, and hence
builds on the Spintronics that the device working principle depends on the electron
spin direction.
Development of Spintronics
• The lower density of state of the spin-up than that of spin-down one at Fermi-level energy.
• The majority and minority spin electrons play important roles of the magneto-electric behaviors, such as magnetoresistance(MR).
Development of Spintronics
%100)(
)()(
21
21
orHHR
HRHRMR
The MR ratio is the variation of the sample resistance under different
magnetic field.
Development of Spintronics
Type Order FieldTemperatu
re
OMR 10-2% 1 T RT
AMR 2 % 10 Oe RT
GMR 5 % 10 Oe RT
CMR 106 % 5 T 100 KTMR 102 % 100~1 Oe RT
Tunneling Magnetoresistance
The energy band structure the 3d ferromagnetic materials near the Fermi level, such as Fe, Co, Ni
EF
Majority
Minority
n↑(EF) n↓(EF)%100)()(
)()(
FF
FF
EnEn
EnEnP
Tunneling Magnetoresistance
↑ ↑
Parallel-state SSLL
PG 2121
Tunneling Magnetoresistance
↑ ↓
AntiParallel-stateLSSL
APG 2121
Tunneling Magnetoresistance
LSSLAPG 2121
SSLLPG 2121
AP
APP
G
GGTMR
SL
SL
P11
111
SL
SL
P22
222
%1001
2
21
21
PP
PPTMR
M. Julliere Phys. Lett. A 54 225 (1975)
Tunneling Magnetoresistance
32
4
2
42
2
2
)exp(64
23
64
2)exp(
2
2
3VA
dh
mAe
dh
meAVA
dh
meJ
h
dmA
24
J. G. Simmons, J. Appl. Phys. 34,2581(1963)
Tunneling Magnetoresistance
-400 -200 0 200 400
-0.0010
-0.0005
0.0000
0.0005
0.0010
Mag
netiz
atio
n (E
MU
)
Magnetic Field(Oe)
→→
←←
→←
←→
-1000 -800 -600 -400 -200 0 200 400 600 800 1000-2
0
2
4
6
8
10
12
14
16
MR
ra
tio (
%)
Magnetic Field (Oe)
→→
←←
→←
←→
Ta 20/CoFe 25/AlOx 1.2/NiFe 30/Ta 40
Tunneling MagnetoresistanceTa 20/CoFe 25/AlOx 1.2 or 1.5/NiFe 30/Ta 40
-1.0 -0.5 0.0 0.5 1.0
-4.0x10-7
-2.0x10-7
0.0
2.0x10-7
4.0x10-7
J (A
mp/
um2 )
DC Bias(Voltage)
Simulator AlOx 1.2nm J-V
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6
-4.0x10-8
-2.0x10-8
0.0
2.0x10-8
4.0x10-8
J (A
mp/
um2 )
DC Bias (Voltage)
Simulator AlOx 1.5nm J-V
AlOx thickness
Barrier WidthBarrier Height
Inaccuracy
1.2 nm 1.126 nm 2.793 eV 0.255 %1.5 nm 1.482 nm 1.839 eV 0.290 %
-1000 -800 -600 -400 -200 0 200 400 600 800 1000
0
2
4
6
8
10
12
MR
Ra
tio (
%)
Magnetic Field (Oe)
Tunneling Magnetoresistance
-2000 -1000 0 1000 2000
-8.0x10-5
-6.0x10-5
-4.0x10-5
-2.0x10-5
0.0
2.0x10-5
4.0x10-5
6.0x10-5
8.0x10-5
Mag
netiz
atio
n (E
MU
)
Magnetic Field (Oe)
Ta 20/MnIr 12/CoFe 3/AlOx 1.2/CoFe 3 /NiFe 45/Ta 20
→→
←← →
←
←→
←←
→←
←→
→→
Spin Torque Transfer
0 100 200 300 400 500
0.00
0.05
0.10
0.15
0.20
Req
uirie
d C
urre
nt (
mA
)
Device Dimension (nm)
Field Induced Current Induced
Jc:5x106 A/cm2
→
←
Spin Torque Transfer
• In 1996, Slonczewski and Berger predicted that the magnetization of a magnetic layer can be reversed by injection of a spin polarized current and spin transfer to the layer.
• Magnetization reversal without application of an external magnetic field would be of considerable interest to switch magnetic microdevices.
Spin Torque TransferSlonczewski brought out that polarized spin current contribute torque is equal to:
eeff Ie
ssg
dt
dScScHs
dt
dS 21222
2 ˆˆˆ
Where γis the gyromagnetic ratio Heff is effect magnetic field c is the direction of symmetry axis of anisotropy αis the damping coefficient
1
23
213
4
ˆˆ314
P
ssPg
Spin Torque Transfer
Write to parallel
Spin Torque Transfer
Write to antiparallel
Spin Torque Transfer
SiO2/Ta 20nm/PtMn 15nm/CoFeB 3nm/Ru 0.8nm/CoFeB 3nm / AlOx 0.7 before oxide/CoFeB 2nm/Ta 40 nm
→
←
Spin Torque Transfer
Beam
holder
45° etching
hold
er
Beam
75° etching
holder
Beam
0° etching Redepositio
n
Spin Torque Transfer
Spin Torque Transfer
Spin Torque Transfer
Wafer
Coil
Source Chamber
ProcessChamber
ICP Power(13.56
MHz)
Bias Power(13.56
MHz) Coller
Inductively Coupled Plasma Reactive Ion Etching
Spin Torque Transfer
Spin Torque Transfer
500 x 250 nm
130 x 130 nm
Spin Torque Transfer
Spin Torque Transfer
Conclusion
• Spin torque transfer effect is more competent than field induced switching for TMR or GMR nano-devices.
• ICP-RIE etching procures higher taper angle and less damage than Ion Beam Etching for TMR fabrication process.
Thank YouFor
Your Attention