We present optical measurements of the transition metal dichalcogenide PdTe2. The reflectivity displays an unusual temperature and energy dependence in the far-infrared, which we show can only be explained by a collapse of the scattering rate at low temperature, resulting from the vicinity of a van Hove singularity near the Fermi energy. An analysis of the optical conductivity suggests that below 150 K a reduction in the available phase space for scattering takes place, resulting in long-lived quasiparticle excitations. We suggest that this reduction in phase space provides experimental evidence for a van Hove singularity close to the Fermi level. Our data furthermore indicates a very weak electron-phonon coupling. Combined this suggests that the superconducting transition temperature is set by the density of states associated with the van Hove singularity.
@article{arxiv.1911.08733,
title = {Scattering rate collapse driven by a van Hove singularity in the Dirac semi-metal PdTe$_{2}$},
author = {Erik van Heumen and Maarten Berben and Linda Neubrand and Yingkai Huang},
journal= {arXiv preprint arXiv:1911.08733},
year = {2019}
}