Light-induced Orbital and Spin Magnetism in $3d$, $4d$, and $5d$ Transition Metals

TL;DR

This paper provides a comprehensive first-principles analysis of light-induced spin and orbital magnetism in transition metals, revealing how light polarization, frequency, and crystal structure influence these effects, advancing understanding in optical magnetism.

Contribution

First detailed first-principles study of spin and orbital inverse Faraday effect in transition metals, highlighting the roles of crystal field and spin-orbit coupling.

Findings

Spin and orbital moments vary with light polarization and frequency.

Crystal field and spin-orbit interaction determine the response.

Effect shows anisotropy with respect to magnetization and crystal structure.

Abstract

Understanding the coherent interplay of light with the magnetization in metals has been a long-standing problem in ultrafast magnetism. While it is known that when laser light acts on a metal it can induce magnetization via the process known as the inverse Faraday effect (IFE), the most basic ingredients of this phenomenon are still largely unexplored. In particular, given a strong recent interest in orbital non-equilibrium dynamics and its role in mediating THz emission in transition metals, the exploration of distinct features in spin and orbital IFE is pertinent. Here, we present a first complete study of the spin and orbital IFE in $3d$, $4d$ and $5d$ transition metals of groups IV$-$XI from first-principles. By examining the dependence on the light polarization and frequency, we show that the laser-induced spin and orbital moments may vary significantly both in magnitude and sign. We underpin the interplay between the crystal field splitting and spin-orbit interaction as the key factor which determines the magnitude and key differences between the spin and orbital response. Additionally, we highlight the anisotropy of the effect with respect to the ferromagnetic magnetization and to the crystal structure. The provided complete map of IFE in transition metals is a key reference point in the field of optical magnetism.