Magnetic-field-induced Fabry-Pérot resonances in helical edge states

Abstract

We study electronic transport across a helical edge state exposed to a uniform magnetic (B- ) field over a finite length. We show that this system exhibits Fabry-Pérot-type resonances in electronic transport. The intrinsic spin anisotropy of the helical edge states allows us to tune these resonances by changing the direction of the B- field while keeping its magnitude constant. This is in sharp contrast to the case of nonhelical one-dimensional electron gases with a parabolic dispersion, where similar resonances do appear in individual spin channels ( and ) separately which, however, cannot be tuned by merely changing the direction of the B- field. These resonances provide a unique way to probe the helical nature of the theory. We study the robustness of these resonances against a possible static impurity in the channel. © 2012 American Physical Society.