We investigate the optical conductivity and far-infrared magneto-optical response of BaNiS2, a simple square-lattice semimetal characterized by Dirac nodal lines that disperse exclusively along the out-of-plane direction. With the magnetic field aligned along the nodal line the in-plane Landau level spectra show a nearly B behavior, the hallmark of a conical-band dispersion with a small spin-orbit coupling gap. The optical conductivity exhibits an unusual temperature-independent isosbestic line, ending at a Van Hove singularity. First-principles calculations unambiguously assign the isosbestic line to transitions across Dirac nodal states. Our work suggests a universal topology of the electronic structure of Dirac nodal lines.
@article{arxiv.2104.05521,
title = {Optical conductivity signatures of open Dirac nodal lines},
author = {D. Santos-Cottin and M. Casula and L. de' Medici and F. Le Mardelé and J. Wyzula and M. Orlita and Y. Klein and A. Gauzzi and A. Akrap and R. P. S. M Lobo},
journal= {arXiv preprint arXiv:2104.05521},
year = {2021}
}