A Symmetry Strategy for Large Bandgap Quantum Anomalous Hall Insulators

ABSTRACT

Quantum anomalous Hall insulators (QAHIs) are an ideal platform for exploring exotic quantum phenomena, yet typically depend on strong relativistic effects to achieve a substantial bandgap. Here, we propose a symmetry‐lowering strategy for designing robust QAHIs without introducing heavy elements. Using the tetragonal space group as a prototypical system, we find that reducing symmetry from P 4/ nmm to Pmmn activates hybridization of distinct orbital sets near the Dirac cone, producing a large topological bandgap in correlated systems. First‐principles calculations identify the Pmmn VAs monolayer as a high‐temperature QAHI with a bandgap of 1018 meV, much larger than 857 meV of its P 4/ nmm counterpart. This strategy also facilitates bandgap engineering in QAHIs via symmetry manipulation, such as strain and substrate applications.