Abstract

Topological materials exhibit exotic properties such as dissipantionless charge and spin currents that could form the basis for novel technological applications such as low-power electronics or spintronics devices. However, many topological materials lose their topological order upon increasing temperature, thus hampering practical applications.

I will describe the interplay between topology and temperature, showing that thermal expansion and electron-phonon coupling contribute similarly to the temperature dependence of the properties of topological materials. Using the Bi2Se3 family of topological insulators as an example, I will explain why increasing temperature tends to destroy topological order. However, I will argue that this is not a fundamental constraint on topological materials, and I will show how it is also possible to design materials in which the opposite behaviour is observed, presenting PbO2 as the first example of a material in which temperature promotes a topologically ordered phase. Finally, I will discuss how temperature may be exploited to identify the correct topological phase of a material, an approach that will prove particularly useful close to the boundary between two phases with different topological order.