In-plane anomalous features in the 3D quantum Hall regime

TL;DR

This paper uncovers novel in-plane magnetic field-induced features in the 3D quantum Hall regime of Weyl semimetals, including unexpected oscillations, unquantized resistance, and disorder-robust transport phenomena, challenging traditional topological interpretations.

Contribution

It reveals new transport phenomena in 3D Weyl semimetals under in-plane magnetic fields, including unconventional oscillations and nonlocal backscattering, expanding understanding of 3D quantum Hall effects.

Findings

Discovery of a new Hall quantum oscillation distinct from Weyl-orbit oscillations.

Observation of unquantized two-terminal magnetoresistance.

Identification of disorder-robust negative longitudinal resistance.

Abstract

Studies of the 3D quantum Hall effect (QHE) have primarily emphasized transport features that mimic the well-established 2D QHE. In this work, we show that qualitatively new features arise when an in-plane magnetic field is applied to a 3D Weyl semimetal in the quantum Hall regime. An unexpected Hall quantum oscillation, distinct from the Weyl-orbit oscillation, coexists with the QHE, along with an unquantized two-terminal magnetoresistance. Moreover, unconventional antichiral transmission enables a peculiar disorder-robust negative longitudinal resistance. Quantization tunable by the lead configuration is further found in this transport geometry. A unique type of nonlocal quantum backscattering channels underlies these phenomena. Our work demonstrates a breakdown of the topological characterization of transport even with 3D Chern numbers and reveals hidden 3D QHE transport properties. It opens a new class of transport measurements and phenomena.