Topological Insulator in an Atomic Liquid (Vol. 50, No. 4)

Topological insulators are a new class of materials whose electronic states are characterized by global topological invariants. Due to their nontrivial topology, these materials are able to conduct electricity on the surface despite being insulating in the bulk. Moreover, the metallic surface is robust against disorder and other imperfections, making topological insulators strong candidates for the building blocks of next-generation electronics technology. Although almost all known topological insulators are crystals, it has recently been shown that topological insulators and superconductors can also exist in the amorphous or glass states, as long as the relevant symmetries are maintained.

This work further generalizes the notion of topological materials by theoretically demonstrating an atomic liquid phase that supports topologically nontrivial electronic structure. Using quantum molecular dynamics simulations, it is shown that by melting a topological crystalline state with elevated temperatures, the resultant liquid phase inherits the nontrivial topology that is characterized by a nonzero Bott index, named after the famous topologist Raoul Bott. This work points to a new systematic approach for searching topological phases in amorphous and liquid systems.

G.-W. Chern, Topological insulator in an atomic liquid, EPL 126, 37002 (2019)
[Abstract]