Quantum Hall effect in topological Dirac semimetals modulated by the Lifshitz transition of the Fermi arc surface states

TL;DR

This paper studies how the Lifshitz transition of Fermi arc surface states affects the quantum Hall effect in topological Dirac semimetals, revealing surface state transitions can disrupt Weyl orbits and alter quantized Hall plateaus.

Contribution

It introduces the role of surface Lifshitz transitions in modulating Weyl orbits and the 3D quantum Hall effect in topological Dirac semimetals, highlighting a new surface state mechanism.

Findings

Surface Lifshitz transition can turn off Weyl orbits.

Quantized Hall plateaus become irregular and thickness-dependent.

Surface state transitions are crucial for stable Weyl orbits and 3D QHE.

Abstract

We investigate the magnetotransport of topological Dirac semimetals (DSMs) by taking into account the Lifshitz transition of the Fermi arc surface states. We demonstrate that a bulk momentum-dependent gap term, which is usually neglected in study of the bulk energy-band topology, can cause the Lifshitz transition by developing an additional Dirac cone for the surface to prevent the Fermi arcs from connecting the bulk Dirac points. As a result, the Weyl orbits can be turned off by the surface Dirac cone without destroying the bulk Dirac points. In response to the surface Lifshitz transition, the Weyl-orbit mechanism for the 3D quantum Hall effect (QHE) in topological DSMs will break down. The resulting quantized Hall plateaus can be thickness-dependent, similar to the Weyl-orbit mechanism, but their widths and quantized values become irregular. Accordingly, we propose that apart from the bulk Weyl nodes and Fermi arcs, the surface Lifshitz transition is also crucial for realizing stable Weyl orbits and 3D QHE in real materials.