Transport by helical edge states of a quantum spin Hall insulator is experimentally characterized by a weakly temperature-dependent mean free path of a few microns and by reproducible conductance oscillations, challenging proposed theoretical explanations. We consider a model where edge electrons experience spatially random Rashba spin-orbit coupling and couple to a magnetic impurity with spin S >= 1/2. In a finite bias steady state, we find for S > 1/2 an impurity induced resistance with a temperature dependence in agreement with experiments. Since backscattering is elastic, interference between different scatterers possibly explains conductance fluctuations.
@article{arxiv.1502.07927,
title = {Backscattering in helical edge states from a magnetic impurity and Rashba disorder},
author = {Lukas Kimme and Bernd Rosenow and Arne Brataas},
journal= {arXiv preprint arXiv:1502.07927},
year = {2016}
}
Comments
8 pages, 3 figures, contains supplemental material, corresponds to published version