Light-induced Nonlinear Resonant Spin Magnetization

TL;DR

This paper demonstrates light-induced nonlinear spin magnetization in centrosymmetric materials, revealing quantum geometric origins and helicity-dependent effects, paving the way for advanced opto-spintronic applications.

Contribution

It introduces the concept of light-induced nonlinear spin magnetization and analyzes its quantum geometric origins in both metallic and insulating systems.

Findings

Significant LNSM predicted in CuMnAs.

Helicity-dependent spin magnetization observed under circularly polarized light.

LNSM can drive nonlinear spin-orbit torques.

Abstract

The optical generation of nonequilibrium spin magnetization plays a crucial role in advancing spintronics, providing ultrafast control of magnetization dynamics without the need for magnetic fields. Here, we demonstrate the feasibility of light-induced nonlinear spin magnetization (LNSM), which becomes a dominant effect in centrosymmetric materials. We reveal the quantum geometric origins of various LNSM contributions in both metallic and insulating systems. Through detailed symmetry analysis, we predict significant LNSM in the antiferromagnetic material CuMnAs. Notably, under circularly polarized light, the spin magnetization exhibits helicity-dependent behavior, reversing with opposite light helicity. These findings open up new possibilities for generating LNSM-driven nonlinear spin-orbit torques and developing innovative opto-spintronic devices.