Electric field control of phonon angular momentum in perovskite BaTiO$_3$

TL;DR

This paper demonstrates that in ferroelectric BaTiO$_3$, external electric fields can control phonon angular momentum directions, opening new avenues for manipulating phenomena dependent on phonon angular momentum.

Contribution

It introduces a first-principles based model explaining how electric polarization influences phonon angular momentum in BaTiO$_3$, revealing a new control mechanism.

Findings

Phonon angular momentum in BaTiO$_3$ is perpendicular to electrical polarization.

Electric fields can manipulate phonon angular momentum directions.

A model explains the relationship between polarization and phonon angular momentum.

Abstract

We find that in BaTiO$_3$ the phonon angular momentum is dominantly pointing in directions perpendicular to the electrical polarization. Therefore, external electric field in ferroelectric BaTiO$_3$ does not control only the direction of electrical polarization, but also the direction of phonon angular momentum. This finding opens up the possibility for electric-field control of physical phenomena that rely on phonon angular momentum. We construct an intuitive model, based on our first-principles calculations, that captures the origin of the relationship between phonon angular momentum and electric polarization.