Floquet Engineering of Nonequilibrium Valley-Polarized Quantum Anomalous Hall Effect with Tunable Chern Number

Here, we propose that Floquet engineering offers a strategy to realize the nonequilibrium quantum anomalous Hall effect (QAHE) with tunable Chern number. Using first-principles calculations and Floquet theorem, we unveil that QAHE related to valley polarization (VP-QAHE) is formed from the hybridization of Floquet sidebands in the two-dimensional family MSi2Z4 (M = Mo, W, V; Z = N, P, As) by irradiating circularly polarized light (CPL). Through the tuning of frequency, intensity, and handedness of CPL, the Chern number of VP-QAHE is highly tunable and up to C = +/- 4, which attributes to light-induced trigonal warping and multiple-band inversion at different valleys. The chiral edge states and quantized plateau of Hall conductance are visible inside the global band gap, thereby facilitating the experimental measurement. Our work not only establishes Floquet engineering of nonequilibrium VP-QAHE with tunable Chern number in realistic materials but also provides an avenue to explore emergent topological phases under light irradiation.

Automated summary

We propose that Floquet engineering can be used to realize the nonequilibrium quantum anomalous Hall effect (QAHE) with tunable Chern number. By irradiating circularly polarized light (CPL), the hybridization of Floquet sidebands in the two-dimensional family MSi2Z4 can lead to the formation of QAHE related to valley polarization (VP-QAHE). The Chern number of VP-QAHE can be highly tunable by adjusting the frequency, intensity, and handedness of CPL, allowing for the exploration of emergent topological phases under light irradiation.