  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.
