# Topological phase transition based on the attractive Hubbard model

## TL;DR

This paper explores how attractive on-site interactions induce a topological phase transition from a band insulator to a quantum anomalous Hall state, enhancing edge state robustness in a two-band Dirac fermion model.

## Contribution

It introduces a theoretical phase diagram showing the transition driven by attractive interactions in a square lattice Dirac fermion system.

## Key findings

- Attractive interactions induce a transition to a quantum anomalous Hall state.
- The nontrivial band gap enlarges with increased attractive interaction.
- Edge states become more localized, improving transport robustness.

## Abstract

We theoretically investigate the effect of an attractive on-site interaction on the two-band magnetic Dirac fermion model based on a square lattice system. When the attractive fermion interaction is taken into account by the mean-field approximation, a phase diagram is obtained. It is found that a quantum phase transition from a band insulator state to quantum anomalous Hall state occurs with increased attractive interaction. For an existing quantum anomalous Hall state, the attractive interaction enlarges its nontrivial band gap and makes the topological edge states more localized, which protects the transport of linear-dispersive edge states against finite-size and further disorder effects.