Floquet-Engineering Topological Phase Transition in Graphene Nanoribbons by Light

Abstract Quasi-one-dimensional (1D) graphene nanoribbons (GNRs) play a crucial role in advancement of next-generation devices. Recent studies have suggested their potential to exhibit unique symmetry-protected topological phases defined by aZ₂ invariant. By employing both the tight-binding model and the Floquet theory, our investigation demonstrates the effective control of the topological phase within quasi-1D armchair GNRs (AGNRs) using elliptically polarized light, unveiling rich topological phase diagrams. Specifically, we observe that varying the amplitude of the light can induce transitions in the band gap (E_g) of AGNRs, leading to multiple changes in the system’sZ₂ invariant. Furthermore, for heterojunctions composed of different AGNR segments, the junction state can be either created or eliminated by the application of elliptically polarized light.