Synopsis: Topological Insulators Feel the Heat

Calculations based on density-functional theory show that certain topological insulators can turn into conventional insulators at high temperature.  
Synopsis figure
M. Crispin-Ortuzar/Memorial Sloan Kettering Cancer Center

Pop into a condensed-matter physics conference today, and you’ll find many talks on topological insulators. Not surprisingly, for they are fascinating materials and might offer a path towards fault-tolerant quantum computing and high-performance electronics. Now, Bartomeu Monserrat and David Vanderbilt from Rutgers University, New Jersey, predict that these materials can turn into normal insulators at high temperature. This surprising finding underscores the importance of considering the role of temperature in future searches for and applications of topological insulators.

The duo calculated the effect of increased temperature on the electronic band structure of topological insulators from the family of materials that includes bismuth selenide and antimony selenide. They used density-functional theory (DFT), the method of choice for calculating the electronic structure of solids and surfaces. They found that increased temperature decreases the band gap of the materials and suppresses their topological conducting surface states, with thermal expansion of the lattice and coupling between electrons and phonons playing equal parts in the process.

These results are at variance with a previous (non-DFT) theoretical study, which found that high temperatures favor topological phases. But that study did not factor in the effect of thermal expansion. What’s more, Monserrat and Vanderbilt derived a phase diagram for antimony selenide that details the temperature and pressure at which the transition to the normal insulating state might occur and hinder potential applications.

This research is published in Physical Review Letters.

–Ana Lopes

Ana Lopes is a Senior Editor of Physics.


Features

More Features »

Announcements

More Announcements »

Subject Areas

Topological InsulatorsCondensed Matter Physics

Previous Synopsis

Biological Physics

Maintaining the Sequence

Read More »

Next Synopsis

Atomic and Molecular Physics

Quantum Droplets Swell to a Macrodrop

Read More »

Related Articles

Synopsis: Instant-Freeze Water
Fluid Dynamics

Synopsis: Instant-Freeze Water

Laser pulses can turn liquid water into an exotic type of ice within a few nanoseconds. Read More »

Viewpoint: Type-II Dirac Fermions Spotted
Quantum Information

Viewpoint: Type-II Dirac Fermions Spotted

Three separate groups report experimental evidence of novel type-II Dirac quasiparticles, suggesting possible applications in future quantum technology. Read More »

Synopsis: Crumpled Graphene
Graphene

Synopsis: Crumpled Graphene

The crumpling of graphene sheets explains a “soft spot” in the material’s mechanical response. Read More »

More Articles