Conventional Superconductivity in Type II Dirac Semimetal PdTe$_2$

TL;DR

This study demonstrates that PdTe$_2$, a material with coexisting topological Dirac semimetallic and superconducting phases, exhibits conventional superconductivity despite its topologically non-trivial electronic structure.

Contribution

The paper provides direct spectroscopic evidence that the superconducting phase in PdTe$_2$ is conventional, contrasting with expectations of unconventional topological superconductivity.

Findings

Superconducting gap of 326 μeV at 0.38 K

Superconductivity follows BCS temperature dependence

At least one transport band is topologically non-trivial

Abstract

The transition metal dichalcogenide PdTe$_2$ was recently shown to be a unique system where a type II Dirac semimetallic phase and a superconducting phase co-exist. This observation has led to wide speculation on the possibility of the emergence of an unconventional topological superconducting phase in PdTe$_2$. Here, through direct measurement of the superconducting energy gap by scanning tunneling spectroscopy (STS), and temperature and magnetic field evolution of the same, we show that the superconducting phase in PdTe$_2$ is conventional in nature. The superconducting energy gap is measured to be 326 $\mu$eV at 0.38 K and it follows a temperature dependence that is well described within the framework of Bardeen-Cooper-Schriefer's (BCS) theory of conventional superconductivity. This is surprising because our quantum oscillation measurements confirm that at least one of the bands participating in transport has topologically non-trivial character.