Quantum Anomalous Hall Phase Stabilized via Realistic Interactions on a Kagome Lattice

TL;DR

This paper demonstrates that weak repulsive interactions on a Kagome lattice can induce a quantum anomalous Hall phase with spontaneous time-reversal symmetry breaking, quantized conductance, and enhanced energy gaps, suggesting feasible experimental realization.

Contribution

It reveals that realistic weak interactions on a Kagome lattice can stabilize a topologically nontrivial quantum anomalous Hall phase through spontaneous symmetry breaking.

Findings

Interaction-driven quantum anomalous Hall effect observed.

Long-range correlations of loop currents confirmed.

Energy gap can be enhanced by moderate second-neighbor interactions.

Abstract

We study the quantum phases of spinless fermion at one-third filling on a Kagome lattice featuring a quadratic band touching Fermi point. In the presence of weak first and second nearest-neighbor repulsive interactions ($V_1$ and $V_2$), we demonstrate an interaction driven quantum anomalous Hall effect by employing exact diagonalization and density-matrix renormalization group methods. The time-reversal symmetry is broken spontaneously by forming loop currents that exhibit long-range correlation. Quantized Hall conductance corresponding to Chern number of $\pm1$ is obtained by measuring the pumped charge through inserting flux in a cylinder geometry. We find that the energy gap, which topologically protects the emerging ground states, can be enhanced remarkably by a moderate $V_2 < V_1$ via calculating the spectrum and charge excitation gaps, which highlights the experimentally feasible scheme of realizing interaction driven topological phase by spatially decaying interactions on topologically trivial lattice models.