"Magnetoconductance of the quantum spin Hall state"

Joseph Maciejko: Xiao-Liang Qi, and Shou-Cheng Zhang; Phys. Rev. B , 12/06/10.

Additional Authors: Xiao-Liang Qi, and Shou-Cheng Zhang

Abstract:

We study numerically the edge magnetoconductance of a quantum spin Hall insulator in the presence of quenched nonmagnetic disorder. For a finite magnetic field B and disorder strength W on the order of the bulk gap Eg, the conductance deviates from its quantized value in a manner which appears to be linear in |B| at small B. The observed behavior is in qualitative agreement with the cusplike features observed in recent magnetotransport measurements on HgTe quantum wells. We propose a dimensional crossover scenario as a function of W, in which for weak disorder W<Eg the edge liquid is analogous to a disordered spinless one-dimensional (1D) quantum wire, while for strong disorder W>Eg, the disorder causes frequent virtual transitions to the two-dimensional (2D) bulk, where the originally 1D edge electrons can undergo 2D diffusive motion and 2D antilocalization.