First order topological phase transition of the Haldane--Hubbard model

TL;DR

This paper demonstrates a first order topological phase transition in the Haldane--Hubbard model, shifting from a Chern insulator to an antiferromagnetic insulator, challenging previous intermediate state findings.

Contribution

It provides evidence of a first order transition in the Haldane--Hubbard model using dynamical cluster approximation, contrasting with prior continuous transition assumptions.

Findings

First order transition from Chern insulator to antiferromagnetic insulator.

Hysteretic behavior observed in double occupancy and spin correlations.

Contrasts with continuous transition in the ionic Hubbard model.

Abstract

We study the interplay of topological band structure and conventional magnetic long-range order in spinful Haldane model with onsite repulsive interaction. Using the dynamical cluster approximation with clusters of up to 24 sites we find evidence of a first order phase transition from a Chern insulator at weak coupling to a topologically trivial antiferromagnetic insulator at strong coupling. These results call into question a previously found intermediate state with coexisting topological character and antiferromagnetic long-range order. Experimentally measurable signatures of the first order transition include hysteretic behavior of the double occupancy, single-particle excitation gap and nearest neighbor spin-spin correlations. This first order transition is contrasted with a continuous phase transition from the conventional band insulator to the antiferromagnetic insulator in the ionic Hubbard model on the honeycomb lattice.