Controlling edge state transport in a HgTe topological insulator by superlattice effect

We investigate theoretically the edge state transport in a HgTe topological insulator under periodic electrical modulation. We find constructive interference of the backscattering amplitudes, leading to the formation of superlattice minigaps and hence complete suppression of the edge state transmission. Consequently, the edge channel can be switched on/off by appropriately tuning the modulation amplitude via gate voltages, even for wide Hall bar with a small finite size effect. We also find efficient conversion between spin-up and spin-down edge channels by the gate-induced Rashba spin-orbit interaction.