Experimentally feasible Na3Bi monolayer: Floquet quantum anomalous Hall effect with a high Chern number

The high-Chern-number quantum anomalous Hall effect (QAHE) hosts multiple dissipationless edge channels, holding both fundamental significance and promise for low-power spintronic applications. Here, we reveal that, unlike the conventional QAHE realized in two-dimensional (2D) ferromagnets, Floquet engineering offers a fertile strategy to achieve the QAHE in 2D nonmagnetic topological insulators, with the Chern number reaching as much as C = ± 3. Moreover, based on analyses of the Z2 invariant, Chern number, and edge states, the hexagonal monolayer of the Dirac semimetal Na3Bi is identified as an experimentally feasible candidate for the proposed Floquet QAHE, in which remarkably a topological phase transition from the nonmagnetic 2D TI to QAHE occurs. Our results greatly enrich the fundamental physical phenomena and expand the domain of QAHE with a high Chern number, which is expected to draw great experimental attention.