Floquet engineering of topological states in realistic quantum materials via light-matter interactions

Abstract

Electronic states in quantum materials can be engineered by light irradiation, which is greatly advanced by ab-initio computational predictions in realistic light-matter coupled systems. Here we review the most recent progresses from first principles computation in the light-driven Floquet steady states and transient dynamical states with topological electronic bands in real crystals. We first introduce the first-principles modeling approach, dubbed time-dependent Wannier scheme, for simulating real quantum materials under light irradiation. Then, we present a few examples of theoretically-predicted Floquet-Bloch electronic bands engineered by time-periodic light fields, which include the three types of Floquet-Dirac fermions in graphene and black phosphorus, the Floquet-Chern flat bands with an unprecedented high flatness ratio of band width over band gap in a Kagome material, and the Floquet conversion between bright and dark valley excitons in monolayer transition-metal dichalcogenides. Next, we show the ultrafast dynamical evolution of Weyl nodal points in orthorhombic WTe₂ driven by a time-aperiodic short light pulse, and discuss the connection between the Floquet and transient states engineered by light. After that, we introduce three prominent experiments, inspired by theoretical predictions, on the light-induced topological Floquet electronic bands in quantum crystalline materials. Finally, we make a brief summary and perspective on the engineering of topological electronic states through light-matter interactions.