Screening properties of the two-dimensional electron gas with spin-orbit coupling

TL;DR

This paper investigates how Rashba spin-orbit coupling affects the screening behavior of a two-dimensional electron gas, revealing new features in particle-hole excitations and collective mode suppression.

Contribution

It provides an analytic calculation of the polarization operator and explores the impact of spin-orbit coupling on screening, collective modes, and the particle-hole continuum in 2D electron gases.

Findings

Extended particle-hole excitation region due to spin-orbit coupling

Suppression of collective modes like plasmons

Potential observation of effects in inelastic Raman scattering

Abstract

We study screening properties of the two-dimensional electron gas with Rashba spin-orbit coupling. Calculating the dielectric function within the random phase approximation, we describe the new features of screening induced by spin-orbit coupling, which are the extension of the region of particle-hole excitations and the spin-orbit-induced suppression of collective modes. The required polarization operator is calculated in an analytic form without any approximations. Carefully deriving its static limit, we prove the absence of a small-$q$ anomaly at zero frequency. On the basis of our results at finite frequencies we establish the new boundaries of the particle-hole continuum and calculate the SO-induced lifetime of collective modes such as plasmons and longitudinal optical phonons. According to our estimates, these effects can be resolved in inelastic Raman scattering. We evaluate the experimentally measurable dynamic structure factor and establish the range of parameters where the described phenomena are mostly pronounced.