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Antiferromagnetic domain - PowerPoint Presentation

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Antiferromagnetic domain - PPT Presentation

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

coo domain afm field domain coo field afm energy barrier motion nucleation wall possibility moke spin cooling direction fitting

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Slide1

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