Inverse Faraday Effect in Rashba two-dimensional electron systems: interplay of spin and orbital effects

TL;DR

This paper theoretically investigates the inverse Faraday effect in Rashba two-dimensional electron systems, revealing how spin-orbit coupling influences orbital and spin magnetizations and their resonant behaviors under circularly polarized light.

Contribution

It provides a detailed theoretical analysis of the orbital contribution to the inverse Faraday effect in Rashba systems, highlighting the interplay of spin and orbital effects and their enhancement near resonance.

Findings

Orbital magnetization can be comparable to or exceed spin magnetization in Rashba metals.

Spin-orbit coupling significantly modifies the orbital magnetization.

Resonant enhancement occurs when radiation frequency matches Rashba spin splitting.

Abstract

The inverse Faraday effect (IFE) refers to the generation of a DC magnetization by circularly polarized light through the transfer of optical angular momentum to electronic degrees of freedom. In conducting systems, this response can arise from two microscopic channels - spin polarization of itinerant electrons and orbital magnetization generated by circulating charge currents. However, the orbital contribution to the inverse Faraday effect in spin-orbit-coupled conducting systems remains largely unexplored. We present a theoretical analysis of the IFE in disordered two-dimensional electron systems with Rashba spin-orbit coupling using both the quantum kinetic equation and Green's-function diagrammatics. We find that in a noninteracting Rashba metal the orbital magnetization is strongly modified by spin-orbit coupling and can become comparable to, or exceed, the spin magnetization for realistic parameter regimes. When the radiation frequency approaches the Rashba spin splitting, both spin and orbital magnetizations exhibit resonant enhancement. These results clarify the microscopic origin of light-induced magnetization and highlight the interplay of spin and orbital mechanisms in optically driven magnetization dynamics in low-dimensional electronic systems.