Mixed type I and type II superconductivity due to intrinsic electronic inhomogeneities in the type II Dirac semimetal PdTe2

TL;DR

This paper investigates the superconducting properties of PdTe2, revealing intrinsic electronic inhomogeneities that cause a mixed type I and type II superconductivity, with implications for its topological characteristics.

Contribution

It demonstrates the presence of intrinsic electronic inhomogeneities in PdTe2 that lead to mixed superconducting behavior, a novel finding in this material.

Findings

Surface inhomogeneities in PdTe2 detected by scanning tunneling spectroscopy.

Mixed type I and type II superconductivity observed.

Spatial distribution of critical fields in the superconducting state.

Abstract

The type II Dirac semimetal PdTe$_2$ is unique in the family of topological parent materials because it displays a superconducting ground state below 1.7 K. Despite wide speculations on the possibility of an unconventional topological superconducting phase, tunneling and heat capacity measurements revealed that the superconducting phase of PdTe$_2$ follows predictions of the microscopic theory of Bardeen, Cooper and Shriefer (BCS) for conventional superconductors. The superconducting phase in PdTe$_2$ is further interesting because it also displays properties that are characteristics of type-I superconductors and are generally unexpected for binary compounds. Here, from scanning tunneling spectroscopic measurements we show that the surface of PdTe$_2$ displays intrinsic electronic inhomegenities in the normal state which leads to a mixed type I and type II superconducting behaviour along with a spatial distribution of critical fields in the superconducting state. Understanding of the origin of such inhomogeneities may be important for understanding the topological properties of PdTe$_2$ in the normal state.