Resonant Spin Hall Effect in Two-Dimensional Electron Systems

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Resonant Spin Hall Effect in Two-Dimensional
Electron Systems
Student Yunjuan Bao Supervisor Shunqing Shen
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GMR, MTJ Read head MRAM
Nonvolatility Increased processing
speed Decreased power consumption Increased
integration densities
Successful Magnetolelctronics
Spintronics
Spin valve Spin injection junction Spin transistor
SOC
Spin Hall effect
Progressing Spin-electronics
Magnetic
controversial
Many Definitions Spin currents
Resonant Spin Hall effect
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What is Spin Hall Effect
Extrinsic type Electrons moving in a
longitudinal x-direction are scattered to y and
y direction respectively for z and -z spins.
Intrinsic type Spins tilt up for gt0 and
tilt down for lt0. The tilting is from the
change of spin-orbit field induced by an electric
field.
Spin-orbit coupling
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Spin-Orbit Coupling
KP theory EFA
Relativistic effect
Dresselhaus
Where is it from
In semiconductor band structures
Luttinger
Rashba
What properties
Rashba effect
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2D Electron Gas in Magnetic Fields
Alternating occupations
Magnetization susceptibility
B
Semiconductor Band structures
Degenerate Landau Levels
KP
SdH Oscillation
Effective Mass
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Resonant Spin Hall Effect
Origin Scaling behavior
Rashba or Dresselhaus
Infinite
Landau System
y
E
Resonant SHE
x
B
Finite
Edge States Current Distribution
Where come from? How about the Spin Hall
Conductance?
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Resonant SHE in Infinite Systems
Model
Level Crossing!!!
Energy spectra
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Linear Response Results
Kicking Point
Spin Hall Conductance
Divergent Peak!!!
Polarization
Reason?
Energy degeneracy at the Fermi surface!
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Scaling Behavior from Nonlinear Method
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Modulating the Resonant Peak
R D
g-factor
Zeeman Splitting!!!
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Resonant SHE in Finite Systems
Model
E
y
x
B
Edge States
Truncation method
Energy dispersed in y-direction Eigenfunction
centered at y0
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Electric Field Effect
No changes to edge currents.
But generating a large currrent in bulk regime.
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Distribution of Polarization and Current
Super saturation
Strong Weak Perturbation
Linear relation
To Measure Spin Currents!!!
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Quantum Hall Conductance and Spin Hall Conductance
Fixed density
Resonance Survives!
Fixed Chemical potential
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Conclusion

• Introduction
• Spin-orbit coupling
• 2D electron gas in magnetic field
• Resonant spin-Hall effect

Origin of the resonant SHE Scaling behaviors

• In infinite systems

Edge states Current distribution Electric field
effect QHC and SHC The resonant SHE holds in
finite systems

• In finite systems

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Thank You