Topological phonons in oxide perovskites controlled by light

TL;DR

This paper demonstrates that oxide perovskites host diverse topological phonons, which can be controlled and tuned by light, strain, and temperature, revealing new ways to manipulate phononic topological states.

Contribution

It reveals the ubiquity of topological phonons in oxide perovskites and shows how photoexcitation can stabilize and tune these states without structural phase changes.

Findings

Topological phonons are common in various oxide perovskites.

Photoexcitation can stabilize and induce topological phonons.

Carrier concentration controls topological transitions.

Abstract

Perovskite oxides exhibit a rich variety of structural phases hosting different physical phenomena that generate multiple technological applications. We find that topological phonons, i.e., nodal rings, nodal lines, and Weyl points, are ubiquitous in oxide perovskites in terms of structures (tetragonal, orthorhombic, and rhombohedral), compounds (BaTiO3, PbTiO3, and SrTiO3), and external conditions (photoexcitation, strain, and temperature). In particular, in the tetragonal phase of these compounds, all types of topological phonons can simultaneously emerge when stabilized by photoexcitation, whereas the tetragonal phase stabilized by thermal fluctuations only hosts a more limited set of topological phonon states. Additionally, we find that the photoexcited carrier concentration can be used to tune the topological phonon states and induce topological transitions even without associated structural phase changes. Overall, we propose oxide perovskites as a versatile platform in which to study topological phonons and their manipulation with light.