Microscopic theory of spin transport
This presentation is the property of its rightful owner.
Sponsored Links
1 / 27

Microscopic theory of spin transport PowerPoint PPT Presentation


  • 226 Views
  • Uploaded on
  • Presentation posted in: General

Microscopic theory of spin transport. K. Hosono, A. Takeuchi, Y. Takezoe, N. Nakabayashi Gen Tatara. Tokyo Metropolitan University. Spin current. r s. j s. E, T. j s. E. S. Spin-orbit. Ferromagnet Spin Seebeck. Spin Hall. Spin pumping. Spin diffusion. Hirsch 99 Murakami 03.

Download Presentation

Microscopic theory of spin transport

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Microscopic theory of spin transport

Microscopic theory of spin transport

K. Hosono, A. Takeuchi, Y. Takezoe, N. Nakabayashi

Gen Tatara

Tokyo Metropolitan University


Microscopic theory of spin transport

Spin current

rs

js

E, T

js

E

S

Spin-orbit

Ferromagnet

Spin Seebeck

Spin Hall

Spin pumping

Spin diffusion

Hirsch 99

Murakami 03

Son 87

Valet 93

Silsbee 79

Tserkovnyak 02

Uchida 08


Microscopic theory of spin transport

Spin current

rs

js

E, T

js

E

S

Spin-orbit

Ferromagnet

Spin Seebeck

Spin Hall

Spin pumping

Spin diffusion

Hirsch 99

Murakami 03

Son 87

Valet 93

Silsbee 79

Tserkovnyak 02

Uchida 08

Pure spin current


Microscopic theory of spin transport

Spin current : Questions

  • These spin currents behave the same?

  • Thermally and electrically induced

  • Local and diffusive

  • What is ms ?

As function of applied field

  • Spin relaxation torque ?


Microscopic theory of spin transport

  • Thermally induced spin currents

  • Takezoe et al.

  • Discrete model (ferromagnetic metal)

  • Local equilibrium

Tn temperature

mn chemical potential

nn magnetization

  • Electron hopping


Microscopic theory of spin transport

  • Uniform magnetization

  • Charge current

  • Spin current

  • Driving force

m,T


Microscopic theory of spin transport

  • Continuum limit

m/m, T/T << 1/d

  • Charge current

S= sT /sB

Aschcroft Mermin

  • Spin current


Microscopic theory of spin transport

  • Non uniform magnetization

  • Gauge field

Anm

  • Spin current

js,i= b(nin) + (in) [c2T+c’ E]

equilibrium

driven

+ n(sBEi+sT iT)

homogeneous

T=Eeff

For spin current


Microscopic theory of spin transport

Spin current : Questions

  • These spin currents behave the same?

  • Thermally and electrically induced

The same

  • Local and diffusive

  • What is ms ?

As function of applied field

  • Spin relaxation torque ?


Microscopic theory of spin transport

  • Local and diffusive spin current

  • Spin pumping + Inverse spin Hall


Microscopic theory of spin transport

Spin pumping effect

Silsbee 79

Tserkovnyak 02

  • Ferro-Normal junction

  • Spin dynamics

 Spin current

rs

  • Silsbee 79

Boltzmann equation

Spin precession

js

 Spin accumulation

 Diffusive spin current

  • Spin continuity equation

Spin precession

 Spin current

  • Tserkovnyak 02


Microscopic theory of spin transport

Detection of spin current

  • Inverse spin Hall effect

  • Saitoh, App. Phys. Lett. 06

Analogy with Ampere’s law

js

j

B

E, j

…?

jB

Spin-orbit

  • Hirsche 99


Microscopic theory of spin transport

Inverse spin Hall effect

  • Saitoh, App. Phys. Lett. 06

Spin-orbit

Charge current

j or E

Spin current

js

Magnetization

dynamics

Spin pumping

Seems O.K. phenomenologically


Microscopic theory of spin transport

Spin pumping

  • Takeuchi Hosono GT, PRB2010

  • Spin current transmission through FN interface

  • sd exchange interaction

  • weak sd interaction perturvation

  • disordered metal vertex correction


Microscopic theory of spin transport

Spin pumping

  • Takeuchi Hosono GT, PRB2010

  • Spin current

Without spin-orbit

rs

Spin accumulation due to spin dynamics

Electron diffusion


Microscopic theory of spin transport

Spin pumping

  • Takeuchi Hosono GT, PRB2010

  • Spin current

rs

No effective field

  • o(q1) contribution may exist

(as interface effect (within mean free path))

  • Charge current (general)

O(q0)

O(q0)


Microscopic theory of spin transport

Spin pumping + Inverse spin Hall

  • Hosono Takeuchi GT, JPSJ 2010

  • Takeuchi Hosono GT, PRB 2010

Spin-orbit interaction

  • Charge current


Microscopic theory of spin transport

Spin pumping + Inverse spin Hall

  • Hosono Takeuchi GT, JPSJ 2010

  • Takeuchi Hosono GT, PRB 2010

  • Charge current

  • Impurity spin-orbit interaction

Charge accumulation

by spin pumping

Inverse spin Hall

Small contribution to js

O(q)

Dominant contribution


Microscopic theory of spin transport

Spin pumping + Inverse spin Hall

  • Hosono Takeuchi GT, JPSJ 2010

  • Takeuchi Hosono GT, PRB 2010

  • Impurity spin-orbit

r

Large diffusive current

Not useful ?

Experiment ?

j

S

j

Inverse spin Hall (Saitoh 06)


Microscopic theory of spin transport

Spin pumping + Inverse spin Hall

  • Depends much on the spin-orbit interaction

  • Impurity spin-orbit

  • Rashba spin-orbit

Large inverse spin Hall current

  • Strong Rashba at interface

Beff=1T for Pt/Co/AlO Miron 2010


Microscopic theory of spin transport

Spin currents: Questions

  • These spin currents behave the same?

  • Thermally and electrically induced

The same

  • Local and diffusive

Different in spin-charge conversion

  • What is ms ?

As function of applied field

  • Spin relaxation torque ?


Microscopic theory of spin transport

Spin chemical potential ?

  • Nakabayashi, cond-mat 2010

Represents spin accumulation

Son 87, Valet&Fert 93

  • Calculated from vertex correction to js

  • Applied electric field

Linear response theory


Microscopic theory of spin transport

Spin chemical potential ?

  • Nakabayashi, cond-mat 2010

c e-r/ls

  • Arises from discontinuity

F N

  • Agrees with phenomenology

ms

  • Spin injection

E

ls


Microscopic theory of spin transport

Spin chemical potential ?

  • Nakabayashi, cond-mat 2010

  • Spin injection

Spin injection

No spin injection


Microscopic theory of spin transport

Spin relaxation torque?

  • Nakabayashi, cond-mat 2010

  • Spin continuity equation

  • Electrically and thermally induced

+gT2T

Arises from discontinuity

T=Eeff

For spin relaxation


Microscopic theory of spin transport

  • Hosono Takeuchi GT, JPSJ 79(2010)

  • Takeuchi Hosono GT, PRB (2010)

  • Nakabayashi, arXiv:1002.0207

  • Takezoe

Summary

  • Thermally and electrically induced spin currents

Equivalent

Spin current, spin relxation

T=Eeff

  • Direct and diffusive spin currents

Inverse spin Hall effect

Different roles

  • Spin chemical potential

Arises from E,2T

  • Spin relaxation torque


Microscopic theory of spin transport

Spin pumping and

Inverse spin Hall effects

-Microscopic study-

Narita

Tokyo

K. Hosono, A. Takeuchi, Y. Takezoe, N. Nakabayashi

Gen Tatara

Mt. Fuji

富士山

Tokyo Metropolitan University

Post doc position : [email protected]


  • Login