Electron-phonon scattering dynamics in ferromagnets on ultrafast timescales: Influence of the phonon temperature

TL;DR

This study models ultrafast magnetization dynamics in ferromagnets considering electron-phonon interactions and phonon temperature effects, revealing limited magnetization quenching and minimal impact of phonon heating on ultrafast timescales.

Contribution

It introduces a dynamical model incorporating spin-orbit coupling, electron-phonon scattering, and phonon temperature changes to analyze ultrafast magnetization responses.

Findings

Maximum magnetization quenching is smaller than experimental observations.

Phonon bath heating does not significantly affect ultrafast magnetization dynamics.

Electron-phonon scattering alone cannot explain the observed quenching.

Abstract

The magnetization response of bulk ferromagnets after excitation by an ultrashort optical pulse is calculated using a dynamical model of the Elliott-Yafet type that includes the effects of the spin-orbit interaction in the ab-initio ferromagnetic band structure, the electron-phonon interaction at the level of Boltzmann scattering integrals, and dynamical changes in the temperature of the phonon bath. Using realistic parameters for the ultrashort optical pulse, the computed maximum magnetization quenching achievable with electron-phonon scattering in a fixed band structure is much smaller than the quenching observed in experiments. Heating of the phonon bath is found to not appreciably change the magnetization dynamics on ultrashort timescales.