Mott Physics and Topological Phase Transition in Correlated Dirac Fermions

TL;DR

This paper explores how strong electron-electron interactions and spin-orbit coupling influence phase transitions in correlated Dirac fermions, revealing transitions from topological insulators to spin liquids or magnetic phases.

Contribution

It provides a qualitative phase diagram of the Kane-Mele-Hubbard model showing the effects of increasing Hubbard U on topological and magnetic phases.

Findings

Transition from topological insulator to spin liquid with increasing U

Transition from topological insulator to antiferromagnetic phase depending on spin-orbit strength

Evolution of bulk bands during the topological quantum phase transition

Abstract

We investigate the interplay between the strong correlation and the spin-orbital coupling in the Kane-Mele-Hubbard model and obtain the qualitative phase diagram via the variational cluster approach. We identify, through an increase of the Hubbard $U$, the transition from the topological band insulator to either the spin liquid phase or the easy-plane antiferromagnetic insulating phase, depending on the strength of the spin-orbit coupling. A nontrivial evolution of the bulk bands in the topological quantum phase transition is also demonstrated.