Effect of inplane electric field on magnetotransport in helical metal

TL;DR

This paper investigates how an in-plane electric field influences magnetotransport phenomena such as conductivity and thermopower in helical surface states of topological insulators, revealing tunable quantum oscillations.

Contribution

It introduces a detailed analysis of the effects of in-plane electric fields on Landau levels and magneto-oscillations in helical metals, a novel aspect in topological surface state research.

Findings

Magneto-oscillation characteristics depend on the in-plane electric field.

Landau level energies can be tuned by electric field variations.

Degeneracy of Landau levels remains unaffected by electric field.

Abstract

The existence of helical surface states in a bulk insulator, with anomalous magneto-electric properties, is a remarkable new development in solid state physics. The linear dispersion of the the fermions leads to a form of Lorentz invariance, with the Fermi velocity playing the role of the velocity of light ($c$). In a crossed electric and magnetic field the single particle states form Landau levels whose energies can be changed by varying the applied \emph{in-plane electric} field. The degeneracy remains constant and is determined by the magnetic field. In the letter we study the nature of the mangeto-oscillation in conductivity and thermopower as a function of the \emph{in-plane electric} field.