Coupling of acoustic phonon to a spin-orbit entangled pseudospin

TL;DR

This paper investigates how acoustic phonons interact with spin-orbit entangled pseudospins, revealing effects like mode splitting, chirality, and Berry curvature modifications under magnetic fields.

Contribution

It introduces a Berry phase term arising from pseudospin-phonon coupling and analyzes its impact on phonon modes in spin-orbit coupled systems.

Findings

Berry phase affects phonon mode splitting

External magnetic field induces phonon chirality

Berry curvature influences phonon dynamics

Abstract

We consider coupling of acoustic phonon to pseudospins consisting of electronic spins locked to orbital angular momentum states. We show that a Berry phase term arises from projection onto the time-dependent lowest energy manifold. We examine consequences on the phonon modes, in particular mode splitting, induced chirality and Berry curvatures under an external magnetic field which Zeeman couples to the pseudospin.