Engineering Quantum Anomalous Hall Effect with a High Chern Number in Nonmagnetic Second-Order Topological Insulator

Quantum anomalous Hall effect (QAHE) with a high Chern number hosts multiple dissipationless edge states, which is of significant fundamental and technological importance in low-dissipation spintronics. Here, in contrast to generally reported QAHE in 2D ferromagnets, the emergence of high-Chern-number QAHE in 2D nonmagnets is theoretically demonstrated. Remarkably, tight-binding model analyses and calculations show that Floquet engineering offers a fertile strategy to achieve the QAHE in 2D nonmagnetic second-order topological insulators (SOTIs), with the Chern number reaching as much as $C=\pm 6$. Moreover, based on the Chern number, corner states, and edge states analyses, the SMoSiN₂ monolayer is identified as an experimentally feasible candidate of the proposed mechanism of Floquet QAHE, where a topological phase transition from the 2D nonmagnetic SOTI to QAHE emerges. These findings pave a technological avenue to bridge the higher-order topology and exotic QAH physics with high feasibility of applications in topological spintronics.