Dynamical signatures of point-gap Weyl semimetal

TL;DR

This paper explores the unique dynamical properties of point-gap Weyl semimetals, a non-Hermitian topological phase, revealing novel surface spectra, boundary modes, and current responses distinct from Hermitian counterparts.

Contribution

It introduces a concrete model of non-Hermitian Weyl semimetals with a topological invariant, predicting new dynamical phenomena and boundary modes not seen in Hermitian systems.

Findings

Predicted a time-dependent current flow along magnetic fields without electric fields.

Discovered a boundary-skin mode localized at wire corners.

Identified experimental signatures in wave-packet dynamics.

Abstract

We demonstrate a few unique dynamical properties of point-gap Weyl semimetal, an intrinsic non-Hermitian topological phase in three dimensions. We consider a concrete model where a pair of Weyl points reside on the imaginary axis of the complex energy plane, opening up a point gap characterized by a topological invariant, the three-winding number $W_3$. This gives rise to surface spectra and dynamical responses that differ fundamentally from those in Hermitian Weyl semimetals. First, we predict a time-dependent current flow along the magnetic field in the absence of an electric field, in sharp contrast to the current driven by the chiral anomaly, which requires both electric and magnetic fields. Second, we reveal a novel type of boundary-skin mode in the wire geometry which becomes localized at two corners of the wire cross section. We explain its origin and show its experimental signatures in wave-packet dynamics.