Scattering Theory of Gilbert Damping

TL;DR

This paper develops a scattering theory approach to analyze the magnetization dynamics in ferromagnets, deriving the Gilbert damping tensor and effective fields, and connecting dissipation with energy currents and spin-pumping effects.

Contribution

It introduces a scattering theory framework for Gilbert damping, expressing damping and effective fields via the scattering matrix, and links dissipation to energy currents and spin-pumping.

Findings

Derived Gilbert damping tensor from scattering matrix

Connected magnetic energy dissipation to energy currents

Established equivalence with Kubo formalism in linear response

Abstract

The magnetization dynamics of a single domain ferromagnet in contact with a thermal bath is studied by scattering theory. We recover the Landau-Liftshitz-Gilbert equation and express the effective fields and Gilbert damping tensor in terms of the scattering matrix. Dissipation of magnetic energy equals energy current pumped out of the system by the time-dependent magnetization, with separable spin-relaxation induced bulk and spin-pumping generated interface contributions. In linear response, our scattering theory for the Gilbert damping tensor is equivalent with the Kubo formalism.