Bad topological semimetals in layered honeycomb compounds

The Mott transition in honeycomb compounds with significant spin-orbit coupling is explored. At finite temperatures we identify a novel semimetallic phase located between a topological insulator and a topological Mott insulator. This semimetal is characterized by having no charge gap, no quasiparticles, and gapped spin excitations with nontrivial topological properties. While charge conduction is incoherent involving mean-free paths violating the Mott-Ioffe-Regel limit, spin excitations can be transported ballistically along the edges giving rise to a quantized spin conductance. Such bad topological semimetal could be searched for close to the Mott transition in certain twisted bilayers of transition metal dicalchogenides.

Automated summary

The Mott transition in honeycomb compounds with significant spin-orbit coupling was explored. At finite temperatures, a novel semimetallic phase was identified between a topological insulator and a topological Mott insulator, characterized by gapped spin excitations with nontrivial topological properties.