We report a topological phase transition in quantum-confined cadmium arsenide (Cd3As2) thin films under an in-plane Zeeman field when the Fermi level is tuned into the topological gap via an electric field. Symmetry considerations in this case predict the appearance of a two-dimensional Weyl semimetal (2D WSM), with a pair of Weyl nodes of opposite chirality at charge neutrality that are protected by space-time inversion (C2T) symmetry. We show that the 2D WSM phase displays unique transport signatures, including saturated resistivities on the order of h/e^2 that persist over a range of in-plane magnetic fields. Moreover, applying a small out-of-plane magnetic field, while keeping the in-plane field within the stability range of the 2D WSM phase, gives rise to a well-developed odd integer quantum Hall effect, characteristic of degenerate, massive Weyl fermions. A minimal four-band k.p model of Cd3As2, which incorporates first-principles effective g factors, qualitatively explains our findings.
@article{arxiv.2306.16794,
title = {Zeeman field-induced two-dimensional Weyl semimetal phase in cadmium arsenide},
author = {Binghao Guo and Wangqian Miao and Victor Huang and Alexander C. Lygo and Xi Dai and Susanne Stemmer},
journal= {arXiv preprint arXiv:2306.16794},
year = {2023}
}
Comments
Accepted for publication in Physical Review Letters