Quantum oscillations of helical edge states of periodically deformed 2D topological insulator in magnetic field

Abstract: We study edge-state transport in a two-dimensional topological insulator with a periodically deformed edge subjected to a uniform magnetic field. Zeeman coupling breaks time-reversal symmetry and enables elastic backscattering, producing oscillations of the forbidden-band widths. In the strong-field regime, the gaps can close completely at discrete field values. In the weak-field regime, we identify an important class of periodic deformations for which the dominant semiclassical scattering is controlled by complex infinity rather than by the nearest turning points. We develop a semiclassical treatment of this process and establish its agreement with perturbation theory and direct numerical calculations. The gap modulation should produce observable oscillations of the edge conductance. Unlike conventional magnetic quantum oscillations, which are periodic in inverse field, the predicted oscillations are periodic in the magnetic field itself, with a period determined by the Fermi velocity and effective g-factor