Edge State Transport in a Quantum Spin Hall Insulator: Effects from Rashba Spin-Orbit Coupling

We analyze the dynamics of the helical edge modes of a quantum spin Hall insulator in the presence of a spatially non-uniform Rashba spin-orbit coupling. The Rashba coupling is found to open a scattering channel which causes localization of the edge modes when the electron-electron interaction or the spatial Rashba variation is sufficiently large. We discuss implications for experiments on edge state transport in HgTe quantum wells.