Topological phonons in oxide perovskites controlled by light

参赛者：

彭博-剑桥大学卡文迪许实验室

作品简介：

钙钛矿氧化物结构丰富，拥有多样的物理性质，可以实现很多应用。BaTiO₃、SrTiO₃ 和 PbTiO₃ 等钙钛矿氧化物可以在四方相、正交相和菱方相等不同结构中实现外尔点、节点线和节点环等多种拓扑声子态，而且这些拓扑态可以被光照、应变和温度等外界环境调节。光照可以在不引发结构相变的前提下改变拓扑声子态，引发拓扑相变。我们发现钙钛矿氧化物是研究拓扑声子及其光调控的完美材料平台。

Perovskite oxides exhibit a rich variety of structural phases hosting different physical phenomena that generate multiple technological applications. We find that topological phonons – 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). 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.