Backscattering in helical edge states from a magnetic impurity and Rashba disorder
Journal article, Peer reviewed
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Original versionPhysical Review B. Condensed Matter and Materials Physics. 2016, 93 (8), 081301-1-081301-5. 10.1103/PhysRevB.93.081301
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.