Quantum phase transitions in the Kane-Mele-Hubbard model

TL;DR

This paper uses quantum Monte Carlo simulations to explore phase transitions in the Kane-Mele-Hubbard model, revealing refined phase boundaries and the nature of various quantum phase transitions in a two-dimensional topological system.

Contribution

It provides a detailed phase diagram of the Kane-Mele-Hubbard model, identifying the nature of phase transitions and the connection between topological insulators and magnetic phases.

Findings

Refined phase boundary for the quantum spin liquid.

Topological insulator remains connected to the Kane-Mele ground state at finite interactions.

Transitions are continuous and belong to the 3D XY universality class.

Abstract

We study the two-dimensional Kane-Mele-Hubbard model at half filling by means of quantum Monte Carlo simulations. We present a refined phase boundary for the quantum spin liquid. The topological insulator at finite Hubbard interaction strength is adiabatically connected to the groundstate of the Kane-Mele model. In the presence of spin-orbit coupling, magnetic order at large Hubbard U is restricted to the transverse direction. The transition from the topological band insulator to the antiferromagnetic Mott insulator is in the universality class of the three-dimensional XY model. The numerical data suggest that the spin liquid to topological insulator and spin liquid to Mott insulator transitions are both continuous.