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

Spontaneous topological phases driven by interactions have been proposed in various lattice models, which, however, have not been observed in experiments. In this work, we report an experimentally feasible scheme of realizing spontaneous quantum anomalous Hall effect (QAHE) driven by spatially decaying interactions between spinless Fermions on a topologically trivial kagome lattice with a quadratic band touching Fermi point. In the presence of weak first and second nearest-neighbor repulsive interactions (V₁ and V₂), the presence of QAHE is demonstrated by employing exact diagonalization and density-matrix renormalization group methods. The time-reversal symmetry is broken spontaneously by forming loop currents with long-range correlation. Quantized Hall conductance is obtained by measuring the pumped charge through inserting flux in a cylinder geometry. We find that the topologically nontrivial energy gap can be enhanced remarkably by a moderate V₂<V₁ via calculating the spectrum and charge excitation gaps.