x-rays on magnetism and domain wall...
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X-rays on Magnetism and Domain Wall X rays on Magnetism and Domain Wall Motion
김 동 현김 동 현충북대학교 물리학과
2008.07.23
Soft X-ray Microscope at BL6.1.2, ALS
time resolutionelement specificity
Δt<70ps
lateral resolution
XMCD Contrast Mechanism for XM-1
absorberX-ray magnetic circular dichroism
right circ.
I0 I1 μ+
xg
I0 I1 μ−
(I /I ) =exp(- x)1 0 μ
element-specifichuge magnetic contrastM·σPhoton
spin-orbit information
1μm
Layer-Resolved Magnetic Imaging Using Element-Specificity
[Pt 0.75nm/Co 0.35nm]*50/Pt 3nm/Tb45Fe55 25nm
p yPhys. Rev. B, accepted (2008)
Fe L3 edge (706eV) Co L3 edge (777eV)
Magnetic Imaging at 15-nm Resolution with Element-Specificity
(C C ) Pt (50 )
p yJ. Appl. Phys (invited) 99, 08H303 (2006)
(Co84Cr16)87Pt13 (50nm)
10%)
TEM analysis
1
10
den
sity
(
0 10 20 30 40 50 600,1
num
ber
d
1,00
1,02
(a.u
.)
0 10 20 30 40 50 60n
grain size (nm)
►imaging at 0 96
0,98
inte
nsi
ty
Co L3 edge @777eV
►imaging at fundamental magnetic length scales
0 20 40 60 80 100 1200,96
distance (nm)
Co L3 edge @777eV
Imaging DW in Magnetic Ring Structures
Phys. Rev. Lett. (2007), Selected for Phys. Rev. Focus
PY ring and AMR measurementPY ring and AMR measurement
Direct Observation of Spin-Torque Phenomenon
1000-nm wide PY ring : Each step after spin-current pulses
Phys. Rev. Lett. 98, 187202 (2007), Selected for Phys. Rev. Focus
1000-nm wide PY ring : Each step after spin-current pulses
Before pulse After ten pulsesAfter ten pulses
Barkhausen Avalanche in Spin-Torque Phenomenon ?
Phys. Rev. Lett. 98, 187202 (2007), Selected for Phys. Rev. Focus
► Efficiency of DW displacement for 49 pulses of 1.0 ns width
Scaling Behavior of First Arrival Time of Traveling Domain Wallg
Phys. Rev. Lett. 100, 167204 (2008),
► Barkhausen avalanche phenomenon in CoCr and CoCrPt films and a scaling behavior of DW traveling time
Various Spin Fluctuation Phenomena
10000
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1000000
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1000000
x 200
x 1000
x 500
tCo = 25 nm τ=4/3
) (A
. U.)
100 1000 10000 10000010
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100 1000 10000 10000010
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1000
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100 1000 10000 10000010
100
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00 x 50P(
s)
2
Phys. Rev. Lett. (2003)
Jump Size, s (μm2)
Ph R L (2007) Phys Rev Lett (2008)Phys. Rev. Lett. (2007) Phys. Rev. Lett. (2008)
Spin Dynamics on ps-Timescale: Field-Driven Case
D.-H. Kim, in preparation
Element-Specific Imaging in Exchange-Biased System
edge -0.040A -0.050A -0.055A -0.060A -0.065A
Py(20nm)/FeMn(5nm)/CoFe(20nm)/Ta(5nm)
y
Ni
Co
Superp
osed
Element-Specific Imaging in Exchange-Biased System
edge -0.040A -0.050A -0.070A -0.080A -0.090A
Py(20nm)/FeMn(10nm)/CoFe(20nm)/Ta(5nm)
y
Ni
Co
Superp
osed
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