Raman Scattering by a Two-Dimensional Fermi Liquid with Spin-Orbit Coupling

TL;DR

This paper develops a microscopic theory for Raman scattering in a two-dimensional Fermi liquid with spin-orbit coupling and magnetic field, revealing collective chiral spin wave modes with unique dispersion features.

Contribution

It introduces a detailed theoretical framework for understanding Raman spectra in 2D Fermi liquids with spin-orbit interactions and magnetic fields, connecting theory with recent experimental observations.

Findings

Identification of chiral spin waves in Raman spectra

Linear-in-q dispersion of collective modes

Dependence of mode frequency on q and B directions

Abstract

We present a microscopic theory of Raman scattering by a two-dimensional Fermi liquid (FL) with Rashba and Dresselhaus types of spin-orbit coupling, and subject to an in-plane magnetic field (B). In the long-wavelength limit, the Raman spectrum probes the collective modes of such a FL: the chiral spin waves. The characteristic features of these modes are a linear-in-q term in the dispersion and the dependence of the mode frequency on the directions of both q and B. All of these features have been observed in recent Raman experiments on CdTe quantum wells.