Floquet interface states in illuminated three-dimensional topological insulators

Recent experiments showed that the surface of a three dimensional topological insulator develops gaps in the Floquet-Bloch band spectrum when illuminated with a circularly polarized laser. These Floquet-Bloch bands are characterized by non-trivial Chern numbers which only depend on the helicity of the polarization of the radiation field. Here we propose a setup consisting of a pair of counter-rotating lasers, and show that one-dimensional chiral states emerge at the interface between the two lasers. These interface states turn out to be spin-polarized and may trigger interesting applications in the field of optoelectronics and spintronics.Comment: 5 pages with 3 figures + supplemental materia

Multiterminal conductance of a floquet topological insulator

We report on simulations of the dc conductance and quantum Hall response of a Floquet topological insulator using Floquet scattering theory. Our results reveal that laser-induced edge states lead to quantum Hall plateaus once imperfect matching with the nonilluminated leads is lessened. The magnitude of the Hall plateaus, however, is not directly related to the number and chirality of all the edge states at a given energy, as usual. Instead, the plateaus are dominated by those edge states adding to the time-averaged density of states. Therefore, the dc quantum Hall conductance of a Floquet topological insulator is not directly linked to topological invariants of the full Floquet bands.publishedVersionFil: Foa Torres, Luis Eduardo Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Foa Torres, Luis Eduardo Francisco. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Pérez Piskunow, Pablo Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Pérez Piskunow, Pablo Matías. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Balseiro, Carlos A. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina.Fil: Balseiro, Carlos A. Comisión Nacional de Energía Atómica. Instituto Balseiro; Argentina.Fil: Balseiro, Carlos A. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Usaj, Gonzalo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina.Fil: Usaj, Gonzalo. Comisión Nacional de Energía Atómica. Instituto Balseiro; Argentina.Fil: Usaj, Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Física de los Materiales Condensado