Current-induced phonon Hall effect

TL;DR

This paper proposes a new mechanism for the phonon Hall effect induced by electric current via electron-phonon interactions, demonstrated in a graphene-like lattice, expanding understanding beyond spin-orbit effects.

Contribution

It introduces a novel current-induced phonon Hall effect mechanism based on electron-phonon interactions, with a theoretical model and demonstration in a graphene-like lattice.

Findings

Finite phonon Hall conductivity observed under electric current

Electron drift influences phonon degrees of freedom

New mechanism extends understanding of PHE beyond magnetic effects

Abstract

Since the first experimental observation of the phonon Hall effect (PHE) in 2005, its physical origin and theoretical explanation have been extensively investigated. While spin-orbit interactions are believed to play important roles under external magnetic fields, nonmagnetic effects are also possible. Here, we propose a mechanism of PHE which is induced by electric current in a nonequilibrium system through electron-phonon interactions. The influence of the drift electrons to the phonon degrees of freedom, as a correction to the Born-Oppenheimer approximation, is represented by an antisymmetric matrix which has the same form as in a typical phonon Hall model. We demonstrate the idea with a graphene-like hexagonal lattice having a finite phonon Hall conductivity under a driven electric current.