Superconductivity under pressure in the Dirac semimetal PdTe2

Abstract

The Dirac semimetal PdTe2 was recently reported to be a type-I superconductor (T c = 1.64 K, mT) with unusual superconductivity of the surface sheath. We here report a high-pressure study, GPa, of the superconducting phase diagram extracted from ac-susceptibility and transport measurements on single crystalline samples. T c (p ) shows a pronounced non-monotonous variation with a maximum T c = 1.91 K around 0.91 GPa, followed by a gradual decrease to 1.27 K at 2.5 GPa. Surface superconductivity is robust under pressure as demonstrated by the large superconducting screening signal that persists for applied dc-fields . Surprisingly, for GPa the superconducting transition temperature at the surface is larger than T c of the bulk. Therefore surface superconductivity may possibly have a non-trivial topological nature. We compare the measured pressure variation of T c with recent results from band structure calculations and discuss the importance of a Van Hove singularity.