Abstract-Terahertz photoresistivity of a high-mobility 3D topological insulator based on a strained HgTe film
We report on a detailed study of the terahertz (THz) photoresistivity in a strained HgTe three-dimensional topological insulator (3D TI) for all Fermi level positions: inside the conduction and valence bands, and in the bulk gap. In the presence of magnetic field we detected a resonance corresponding to the cyclotron resonance (CR) in top surface Dirac fermions (DF) and examined the nontrivial dependence of the surface state cyclotron mass on the Fermi level position. We also detected additional resonant features at moderate electron densities and demonstrated that they are caused by the interaction of surface DF and bulk electrons. At high electron densities, we observed THz radiation induced 1/B-periodic low-field magneto-oscillations coupled to harmonics of the CR and demonstrated that they have a common origin with microwave-induced resistance oscillations (MIRO) previously observed in high mobility GaAs based heterostructures.
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