Scattering rate collapse driven by a van Hove singularity in the Dirac semi-metal PdTe$_{2}$

TL;DR

This study reveals a collapse in scattering rate in PdTe$_{2}$ driven by a van Hove singularity near the Fermi level, affecting its optical properties and potentially influencing its superconductivity.

Contribution

It provides experimental evidence linking a van Hove singularity to scattering rate collapse and superconductivity in PdTe$_{2}$, a transition metal dichalcogenide.

Findings

Scattering rate collapses at low temperature due to van Hove singularity.

Reduction in scattering phase space below 150 K.

Weak electron-phonon coupling in PdTe$_{2}$.

Abstract

We present optical measurements of the transition metal dichalcogenide PdTe$_{2}$. 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.