Weyl semimetal to metal phase transitions driven by quasiperiodic potentials

TL;DR

This paper investigates how quasiperiodic potentials affect three-dimensional Weyl and Dirac semimetals, revealing a sequence of phase transitions from semimetal to metal and back, with distinct critical behaviors from random disorder.

Contribution

It provides the first detailed numerical analysis of phase transitions in Weyl semimetals driven by quasiperiodic potentials, highlighting unique critical properties.

Findings

Semimetal remains stable under weak quasiperiodic potentials.

Transitions include semimetal to metal, then to inverted semimetal, and back to metal.

Density of states jumps abruptly at quasiperiodic transitions.

Abstract

We explore the stability of three-dimensional Weyl and Dirac semimetals subject to quasiperiodic potentials. We present numerical evidence that the semimetal is stable for weak quasiperiodic potentials, despite being unstable for weak random potentials. As the quasiperiodic potential strength increases, the semimetal transitions to a metal, then to an "inverted" semimetal, and then finally to a metal again. The semimetal and metal are distinguished by the density of states at the Weyl point, as well as by level statistics, transport, and the momentum-space structure of eigenstates near the Weyl point. The critical properties of the transitions in quasiperiodic systems differ from those in random systems: we do not find a clear critical scaling regime in energy; instead, at the quasiperiodic transitions, the density of states appears to jump abruptly (and discontinuously to within our resolution).