Type I superconductivity in the Dirac semimetal PdTe2

TL;DR

This study reveals that PdTe2, previously thought to be a topological Dirac semimetal, is actually a Type I superconductor with unique surface superconductivity properties, challenging prior assumptions about its topological nature.

Contribution

The paper provides the first detailed magnetic and transport measurements showing PdTe2 is a Type I superconductor, contrary to expectations based on its classification as a Dirac semimetal.

Findings

PdTe2 is a Type I superconductor with Tc = 1.64 K.

Observation of the intermediate state in PdTe2.

Superconductivity persists on the surface for H > Hc.

Abstract

The superconductor PdTe$_2$ was recently classified as a Type II Dirac semimetal, and advocated to be an improved platform for topological superconductivity. Here we report magnetic and transport measurements conducted to determine the nature of the superconducting phase. Surprisingly, we find that PdTe$_2$ is a Type I superconductor with $T_c = 1.64$ K and a critical field $\mu_0 H_c (0) = 13.6$ mT. Our crystals also exhibit the intermediate state as demonstrated by the differential paramagnetic effect. For $H > H_c$ we observe superconductivity of the surface sheath. This calls for a close examination of superconductivity in PdTe$_2$ in view of the presence of topological surface states.