Ab initio investigation of Elliott-Yafet electron-phonon mechanism in laser-induced ultrafast demagnetization

TL;DR

This study uses first-principles calculations to analyze the Elliott-Yafet electron-phonon mechanism in ultrafast laser-induced demagnetization of ferromagnetic nickel, finding it contributes minimally to the observed rapid demagnetization.

Contribution

First-principles calculation of the spin-flip Eliashberg function for Ni to quantify the electron-phonon contribution to ultrafast demagnetization.

Findings

Increased spin-flip probabilities for thermalized electrons but negligible demagnetization rate.

Non-equilibrium electrons show larger demagnetization rates, yet still too small to explain femtosecond demagnetization.

Electron-phonon spin-flip scattering alone cannot account for the ultrafast demagnetization observed experimentally.

Abstract

The spin-flip (SF) Eliashberg function is calculated from first-principles for ferromagnetic Ni to accurately establish the contribution of Elliott-Yafet electron-phonon SF scattering to Ni's femtosecond laser-driven demagnetization. This is used to compute the SF probability and demagnetization rate for laser-created thermalized as well as non-equilibrium electron distributions. Increased SF probabilities are found for thermalized electrons, but the induced demagnetization rate is extremely small. A larger demagnetization rate is obtained for {non-equilibrium} electron distributions, but its contribution is too small to account for femtosecond demagnetization.