Floquet valley-polarized quantum anomalous Hall state in nonmagnetic heterobilayers
Fangyang Zhan, Zhen Ning, Li‐Yong Gan, Baobing Zheng, Jing Fan, Rui Wang
Abstract
The valley-polarized quantum anomalous Hall (VQAH) state, which forwards a strategy for combining valleytronics and spintronics with nontrivial topology, attracts intensive interest in condensed-matter physics. So far, the exploration of VQAH states has still been limited to magnetic systems. Here, using the low-energy effective model and Floquet theorem, we propose an alternative mechanism to realize the Floquet VQAH state in nonmagnetic heterobilayers under light irradiation. We then realize this proposal via first-principles calculations in transition metal dichalcogenide heterobilayers, which initially possess the time-reversal invariant valley quantum spin Hall (VQSH) state. By irradiating circularly polarized light, the time-reversal invariant VQSH state can evolve into the VQAH state, behaving as an optically switchable topological spin-valley filter. These findings not only offer a rational scheme to realize the VQAH state in periodically driven nonmagnetic systems, but also pave a fascinating path for designing topological spintronic and valleytronic devices with high tunability. Our proposal can also be extended to design the general QAH effect without magnetic orders.