Zeeman field-induced two-dimensional Weyl semimetal phase in cadmium arsenide

Abstract

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.

Accepted for publication in Physical Review Letters

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• Evidence for Two-dimensional Weyl Fermions in Air-Stable Monolayer PtTe${}_{1.75}$
• Theory for Cd${}_3$As${}_2$ thin films in the presence of magnetic fields
• Engineering rich two-dimensional higher-order topological phases by flux and periodic driving
• Artificial moiré engineering for an ideal BHZ model
• Lifshitz transitions and Weyl semimetals from a topological superconductor with supercurrent flow
• Emergent topology in thin films of nodal line semimetals
• Wiedemann-Franz behavior at the Weyl points in compressively strained HgTe