Anisotropic plasmons in a two-dimensional electron gas with spin-orbit interaction

TL;DR

This paper explores how combined Rashba and Dresselhaus spin-orbit interactions create anisotropic plasmon behaviors in 2D electron gases, enabling control over plasmon propagation and revealing conditions where spin-orbit effects vanish.

Contribution

It demonstrates the significant impact of linear spin-orbit interactions on plasmon spectra and identifies a special case where these effects disappear.

Findings

Plasmon propagation is directionally dependent due to spin-orbit coupling.

The dynamical structure factor varies over several decades, affecting plasmon filtering.

Equal strengths of Rashba and Dresselhaus interactions eliminate spin-orbit effects in the response.

Abstract

Spin-orbit coupling induced anisotropies of plasmon dynamics are investigated in two-dimensional semiconductor structures. The interplay of the linear Bychkov-Rashba and Dresselhaus spin-orbit interactions drastically affects the plasmon spectrum: the dynamical structure factor exhibits variations over several decades, prohibiting plasmon propagation in specific directions. While this plasmon filtering makes the presence of spin-orbit coupling in plasmon dynamics observable, it also offers a control tool for plasmonic devices. Remarkably, if the strengths of the two interactions are equal, not only the anisotropy, but all the traces of the linear spin-orbit coupling in the collective response disappear.