Evolution of Weyl orbit and quantum Hall effect in Dirac semimetal Cd3As2

TL;DR

This study demonstrates the evolution of Weyl orbits and the emergence of a quantum Hall effect in Dirac semimetal Cd3As2 nanoplates, revealing surface transport dominance and Zeeman splitting effects.

Contribution

It provides experimental evidence of Weyl orbit-induced quantum Hall states in Dirac semimetals, highlighting the role of surface states and magnetic field effects.

Findings

Observation of crossover from multiple- to single-frequency SdH oscillations

Development of quantum Hall state with non-zero longitudinal resistance

Detection of Zeeman splitting and Landau level quantization

Abstract

Owing to the coupling between open Fermi arcs on opposite surfaces, topological Dirac semimetals exhibit a new type of cyclotron orbit in the surface states known as Weyl orbit. Here, by lowering the carrier density in Cd3As2 nanoplates, we observe a crossover from multiple- to single-frequency Shubnikov-de Haas (SdH) oscillations when subjected to out-of-plane magnetic field, indicating the dominant role of surface transport. With the increase of magnetic field, the SdH oscillations further develop into quantum Hall state with non-vanishing longitudinal resistance. By tracking the oscillation frequency and Hall plateau, we observe a Zeeman-related splitting and extract the Landau level index as well as sub-band number. Different from conventional two-dimensional systems, this unique quantum Hall effect may be related to the quantized version of Weyl orbits. Our results call for further investigations into the exotic quantum Hall states in the low-dimensional structure of topological semimetals.