Dispersive Drumhead States in Nodal-Line Semimetal Junctions

TL;DR

This paper investigates the electronic states at interfaces between topological nodal-line semimetals and trivial insulators or other semimetals, revealing dispersive interface states influenced by the nodal radius and interface smoothness.

Contribution

It introduces a low-energy model to characterize interface states in nodal-line semimetals, highlighting their dependence on material parameters and proposing experimental detection methods.

Findings

Identification of zero-energy and dispersive interface states

Dependence of states on nodal radius and interface smoothness

Proposals for optical detection in experiments

Abstract

We consider a smooth interface between a topological nodal-line semimetal and a topologically trivial insulator (e.g., the vacuum) or another semimetal with a nodal ring of different radius. Using a low-energy effective Hamiltonian including only the two crossing bands, we show that these junctions accommodate a two-dimensional zero-energy level and a set of two-dimensional dispersive bands, corresponding to states localized at the interface. We characterize the spectrum, identifying the parameter ranges in which these states are present, and highlight the role of the nodal radius and the smoothness of the interface. We also suggest material-independent ways to detect and identify these states, using optical conductivity and infrared absorption spectroscopy in magnetic field.