Engineering edge-state currents at the interface between narrow ribbons of two-dimensional topological insulators

We consider a junction between two semi-infinite narrow ribbons of a two-dimensional (2D) topological insulator (TI) and calculate the electron current through the interface carried by one-dimensional (1D) edge states formed in the bulk band gap. In addition to an abrupt interface between ribbons, we also consider a configuration where one or two rectangular islands of finite length are sandwiched between these ribbons. We demonstrate that it is feasible to create “current-on” and “current-off” states by modifying the energy dispersion of 1D interface edge states and the resonant levels localized at the boundary of the island regions.