Fermi-arc metals

TL;DR

This paper predicts a new metallic state called Fermi-arc metal in Weyl-semimetal superstructures, characterized by extended Fermi surfaces from Fermi arc-like states, exhibiting unique quantum properties and transport phenomena.

Contribution

It introduces the concept of Fermi-arc metals with anisotropic Fermi surfaces and demonstrates their unique quantum and transport properties compared to traditional Weyl semimetals.

Findings

Fermi-arc metals have extended, anisotropic Fermi surfaces.

They exhibit the chiral anomaly similar to Weyl semimetals.

Quantum oscillations are absent despite the Fermi surface presence.

Abstract

We predict a novel metallic state of matter that emerges in a Weyl-semimetal superstructure with spatially varying Weyl-node positions. In the new state, the Weyl nodes are stretched into extended, anisotropic Fermi surfaces, which can be understood as being built from Fermi arc-like states. This "Fermi-arc metal" exhibits the chiral anomaly of the parental Weyl semimetal. However, unlike in the parental Weyl semimetal, in the Fermi-arc metal the "ultra-quantum state", in which the anomalous chiral Landau level is the only state at the Fermi energy, is already reached for a finite energy window at zero magnetic field. The dominance of the ultra-quantum state implies a universal low-field ballistic magnetoconductance and the absence of quantum oscillations, making the Fermi surface "invisible" to de Haas-van Alphen and Shubnikov-de Haas effects, although it signifies its presence in other response properties.