Coexistence of type-I and type-II superconductivity in topological superconductor PdTe$_2$

TL;DR

This study uses muon spin rotation to reveal that PdTe2 exhibits a coexistence of type-I and type-II superconductivity, clarifying its superconducting phase diagram and contrasting previous findings.

Contribution

The paper provides the first detailed muon spin rotation analysis confirming mixed superconductivity in PdTe2 and maps its phase diagram.

Findings

PdTe2 shows coexistence of type-I and type-II superconductivity.

Bulk superconductivity is destroyed above 225 G, lower than previously reported.

A detailed superconducting phase diagram for PdTe2 is established.

Abstract

The type-II Dirac semimetal PdTe2 was recently reported to be a type-I superconductor with a superconducting transition temperature Tc = 1.65 K. However, the recent results from tunneling and point contact spectroscopy suggested the unusual state of a mixture of type-I and type-II superconductivity. These contradictory results mean that there is no clear picture of the superconducting phase diagram and warrants a detailed investigation of the superconducting phase. We report here the muon spin rotation and relaxation ($\mu$SR) measurements on the superconducting state of the topological Dirac semimetal PdTe2. From $\mu$SR measurements, we find that PdTe2 exhibits mixed type-I/type-II superconductivity. Using these results a phase diagram has been determined. In contrast to previous results where local type-II superconductivity persists up to Hc2 = 600 G, we observed that bulk superconductivity is destroyed above 225 G.