Disorder-driven exceptional lines and Fermi ribbons in tilted nodal-line semimetals

TL;DR

This paper explores how disorder and tilt in three-dimensional nodal-line semimetals create non-Hermitian effects, leading to exceptional lines and Fermi ribbons with topological properties, expanding the understanding of non-Hermitian topological phases.

Contribution

It demonstrates that disorder combined with tilt induces exceptional lines and Fermi ribbons in nodal-line semimetals, revealing a new paradigm for non-Hermitian topological phases.

Findings

Disorder and tilt generate exceptional lines in the spectrum.

Fermi ribbons form boundaries where the energy gap vanishes.

Shape and orientation of Fermi ribbons depend on tilt and disorder properties.

Abstract

We consider the impact of disorder on the spectrum of three-dimensional nodal-line semimetals. We show that the combination of disorder and a tilted spectrum naturally leads to a non-Hermitian self-energy contribution that can split a nodal line into a pair of exceptional lines. These exceptional lines form the boundary of an open and orientable bulk Fermi ribbon in reciprocal space on which the energy gap vanishes. We find that the orientation and shape of such a disorder-induced bulk Fermi ribbon is controlled by the tilt direction and the disorder properties, which can also be exploited to realize a twisted bulk Fermi ribbon with nontrivial winding number. Our results put forward a paradigm for the exploration of non-Hermitian topological phases of matter.