Elastic backscattering of quantum spin Hall edge modes from Coulomb interactions with non-magnetic impurities

Abstract

We demonstrate that electrostatic interactions between helical electrons at the edge of a quantum spin Hall insulator and a dynamical impurity can induce quasi-elastic backscattering. Modelling the impurity as a two-level system, we show that transitions between counterpropagating Kramers-degenerate electronic states can occur without breaking time-reversal symmetry, provided that the impurity also undergoes a transition. The associated electrical resistance has a weak temperature dependence down to a non-universal temperature scale. Our results extend the range of known backscattering mechanisms in helical edge modes to include scenarios where electron tunnelling out of the system is absent.

6 + 5 pages, 3 figures

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Cited by in corpus (5)

• Nonlinear optical absorption and photocurrents in topological insulators
• Violation and Revival of Kramers' Degeneracy in Open Quantum Systems
• Suppression of ballistic helical transport by isotropic dynamical magnetic impurities
• Robust qubit interactions mediated by photonic topological edge states
• Thermal dissipation of the quantum spin Hall edge states in HgTe/CdTe quantum well