Correlation effects on topological insulator

TL;DR

This paper investigates how strong electron correlations influence topological phases in a two-sublattice system, revealing phase transitions between topological insulators, trivial insulators, and antiferromagnetic states, with implications for solid state and cold atom experiments.

Contribution

It demonstrates how onsite interactions and sublattice energy differences induce topological phase transitions, including the emergence of quantum anomalous Hall states, in correlated two-sublattice systems.

Findings

Interaction U drives transition from quantum spin Hall to antiferromagnetic Mott insulator.

Large sublattice energy difference can induce quantum anomalous Hall state.

Proposed experimental schemes for cold atom realization and detection.

Abstract

The strong correlation effects on topological insulator are studied in a two-sublattice system with an onsite single-particle energy difference $\Delta$ between two sublattices. At $\Delta=0$, increasing the onsite interaction strength $U$ drives the transition from the quantum spin Hall insulating state to the non-topological antiferromagnetic Mott-insulating (AFMI) state. When $\Delta$ is larger than a certain value, a topologically trivial band insulator or AFMI at small values of $U$ may change into a quantum anomalous Hall state with antiferromagnetic ordering at intermediate values of $U$. Further increasing $U$ drives the system back into the topologically trivial state of AFMI. The corresponding phenomena is observable in the solid state and cold atom systems. We also propose a scheme to realize and detect these effects in cold atom systems.