Magnetization dissipation in ferromagnets from scattering theory

Magnetization dissipation in ferromagnets from scattering theory

Brataas, A.
Tserkovnyak, Y.
Bauer, G.E.W.

Applied Sciences

QN/Quantum Nanoscience

2011-08-05

The magnetization dynamics of ferromagnets is often formulated in terms of the Landau-Lifshitz-Gilbert (LLG) equation. The reactive part of this equation describes the response of the magnetization in terms of effective fields, whereas the dissipative part is parametrized by the Gilbert damping tensor. We formulate a scattering theory for the magnetization dynamics and map this description on the linearized LLG equation by attaching electric contacts to the ferromagnet. The reactive part can then be expressed in terms of the static scattering matrix. The dissipative contribution to the low-frequency magnetization dynamics can be described as an adiabatic energy pumping process to the electronic subsystem by the time-dependent magnetization. The Gilbert damping tensor depends on the time derivative of the scattering matrix as a function of the magnetization direction. By the fluctuation-dissipation theorem, the fluctuations of the effective fields can also be formulated in terms of the quasistatic scattering matrix. The theory is formulated for general magnetization textures and worked out for monodomain precessions and domain-wall motions. We prove that the Gilbert damping from scattering theory is identical to the result obtained by the Kubo formalism.

https://doi.org/10.4233/uuid:a6b4ab4b-208d-4240-8357-e397e58f3d92

https://doi.org/10.1103/PhysRevB.84.054416

American Physical Society

1098-0121

http://link.aps.org/doi/10.1103/PhysRevB.84.054416

Physical Review B, 84 (5), 2011

Institutional Repository

journal article

© 2011 the Author(s)
American Physical Society