Electric Quantum Oscillation in Weyl Semimetals

TL;DR

This paper develops a comprehensive nonequilibrium quantum transport theory for Weyl semimetals, revealing complex phenomena like electric quantum oscillation, which is a topologically protected resonant current oscillation under electric fields.

Contribution

It introduces a full nonequilibrium quantum transport framework for the chiral anomaly in Weyl semimetals, linking Bloch oscillations to electric quantum oscillations.

Findings

Identification of electric quantum oscillation as a resonant current phenomenon

Observation of non-Ohmic behavior preceding quantum oscillations

Theoretical prediction of topologically protected oscillations in Weyl semimetals

Abstract

Electronic transport in Weyl semimetals is quite extraordinary due to the topological property of the chiral anomaly generating the charge pumping between two distant Weyl nodes with opposite chiralities under parallel electric and magnetic fields. Here, we develop a full nonequilibrium quantum transport theory of the chiral anomaly, based on the fact that the chiral charge pumping is essentially nothing but the Bloch oscillation. Specifically, by using the Keldysh nonequilibrium Green function method, it is shown that there is a rich structure in the chiral anomaly transport, including the negative magnetoresistance, the non-Ohmic behavior, the Esaki-Tsu peak, and finally the resonant oscillation of the DC electric current as a function of electric field, called the electric quantum oscillation. We argue that, going beyond the usual behavior of linear response, the non-Ohmic behavior observed in BiSb alloys can be regarded as a precursor to the occurrence of electric quantum oscillation, which is both topologically and energetically protected in Weyl semimetals.