dynamics in Fe CoO System Qian Li Jie Zhu Tianping Ma Yan Huo Yizheng Wu Department of Physics Fudan University Shanghai China Ⅰ Introduction Ⅱ Fe CoO coupling characterization ID: 809938
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Antiferromagnetic domain dynamics in Fe/CoO SystemQian Li, Jie Zhu, Tianping Ma, Yan Huo, Yizheng WuDepartment of Physics, Fudan University, Shanghai, China
Ⅰ Introduction
Ⅱ Fe/
CoO
coupling characterization
Ⅲ AFM domain dynamics-‘training’ effect
Ⅳ AFM energy barrier determined by temperature dependence measurement
Ⅳ Field dependence of energy barrier
Ⅴ Discussion
Ⅵ Conclusion
CoO
[110
]
Field cooling direction0
CoO
[110
]
Field cooling direction
Sample
Polarizer
Polarizer
Laser
Photodiode
Magnet
MOKE set up
MgO
capping(4nm)
Fe (25nm)
CoO
(6nm)
MgO
sub(001)
CoO
[110
]
Field cooling direction
n——field switching times
S——AFM flipped spin domain area
——coefficient of domain nucleation possibility per field switching
——
coefficient of
domain motion
possibility per
field switching
142K
138K
Fitting formula
attempt frequency
energy barrier
Domain nucleation
Domain wall motion
Fitting Curve
Training field:600Oe
Fitting formula
Uniaxial anisotropy easy axis is along field cooling direction.
Perpendicular coupling
between Fe/
CoO
L-MOKE
T-MOKE
Our model
Monte Carlo simulation
Domain nucleation possibility-A
Domain wall motion possibility-B
CoO
spin
Exchange-spring model
FM
AFM
hopping
A
FM energy
In high field, both barrier energy increases with field increases.
In the low field, the domain nucleation barrier energy increases sharply while the domain motion barrier energy saturates.
AFM domain structure is important!
What is AFM domain dynamics under thermal excitation
?
82K
82K
143K
FM
AFM
Exchange bias
Exchange coupling
Training effect……
thermal excitation
How to determine AFM domain nucleation and wall motion energy barrier more directly?
PRB 57,1085(1998)
Co/
Pd
multilayer
PRB 75,014434(2007)
NiO
/
NiCoFe
Magnetization
reversal
Domain nucleation
Domain wall motion
AFM magnetization reversal process are clearly revealed in Fe/
CoO
system.
AFM domain nucleation and wall motion energy barrier is directly determined from T
depedence
of
CoO
training process.
Arrhenius law
CoO
spin configuration
Mr
Ms
Mr
ratio=
Mr
/
Ms
I
1
I
2
RL3=I
1
/I
2
Use XMLD to determine
CoO
spin orientation
Two mechanisms for
CoO
magnetization reversal
Transverse
Longitudinal
Transverse
Longitudinal
MOKE