From single-gap to multi-gap topological materials

Topology has become a powerful tool to classify and understand materials. The standard paradigm divides the energy bands into two groups separated by a gap, or with at most some low-dimensional band crossings. Single-gap topological materials include topological insulators, Chern insulators, and topological semimetals. Recent work has extended these ideas to multi-gap systems, in which the energy bands are separated into three or more groups. The resulting phases can be characterized using the Euler class, and exhibit some interesting properties such as non-Abelian charges in the bulk.

In this talk, I will describe our work using first principles calculations to explore topological phases in materials, including both electronic and phononic spectra. In the context of single-gap topology, I will describe the interplay between temperature and topology in electronic systems; while in the context of multi-gap topology, I will present the manipulation of non-Abelian band nodes in phononic systems.

Zoom Link: https://pitp.zoom.us/j/93085720537?pwd=RlhrVFJZU1RmY284Nm5xUXRJakdMZz09