Ultrafast spin-lattice relaxation in ferromagnets including effective spin-orbit fields

TL;DR

This paper explores the microscopic mechanisms of ultrafast demagnetization in ferromagnets, emphasizing the role of electron-phonon interactions, spin precession, and effective spin-orbit fields in spin dynamics.

Contribution

It introduces a detailed model showing how spin precession around internal spin-orbit fields influences ultrafast spin-lattice relaxation in ferromagnets.

Findings

Spin precession around effective spin-orbit fields affects demagnetization dynamics.

Fast precession averages out transverse spin components, mimicking spin-flip transitions.

Electron-phonon interactions are key to ultrafast spin-lattice relaxation.

Abstract

We investigate ultrafast demagnetization due to electron-phonon interaction in a model band-ferromagnet. We show that the microscopic mechanism behind the spin dynamics due to electron-phonon interaction is the interplay of scattering and the precession around momentum-dependent effective internal spin-orbit magnetic fields. The resulting magnetization dynamics can only be mimicked by spin-flip transitions if the spin precession around the internal fields is sufficiently fast (compared to the scattering time) so that it averages out the transverse spin components.