Many-body theory of ultrafast demagnetization and angular momentum transfer in ferromagnetic transition metals

TL;DR

This paper uses a many-electron model to provide a detailed microscopic understanding of laser-induced ultrafast demagnetization in ferromagnetic transition metals, highlighting the roles of spin-orbit interactions and angular momentum transfer.

Contribution

It introduces a rigorous microscopic model that explains the mechanisms of ultrafast demagnetization and angular momentum transfer, consistent with conservation laws.

Findings

Demagnetization efficiency approaches 100% in excited states

Local spin-orbit interactions and interatomic hopping cause breakdown of ferromagnetic correlations

Microscopic insights into spin and angular momentum transfer mechanisms

Abstract

Exact calculated time evolutions in the framework of a many-electron model of itinerant magnetism provide new insights into the laser-induced ultrafast demagnetization observed in ferromagnetic (FM) transition metal thin films. The interplay between local spin-orbit interactions and interatomic hopping is shown to be at the origin of the observed post-excitation breakdown of FM correlations between highly stable local magnetic moments. The mechanism behind spin- and angular-momentum transfer is revealed from a microscopic perspective by rigorously complying with all fundamental conservation laws. An energy-resolved analysis of the time evolution shows that the efficiency of the demagnetization process reaches almost 100% in the excited states.