Superconductivity under pressure in the Dirac semimetal PdTe2

Abstract

The Dirac semimetal PdTe${}_2$ was recently reported to be a type-I superconductor ($T_c=$1.64 K, ${\mu }_0{H}_c(0)=13.6$ mT) with unusual superconductivity of the surface sheath. We here report a high-pressure study, $p\le 2.5$ 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. The critical field of bulk superconductivity in the limit $T\to 0$, $H_c(0,p)$, follows a similar trend and consequently the $H_c(T,p)$-curves under pressure collapse on a single curve: $H_c(T,p)=H_c(0,p)[1-(T/T_c(p){)}^2]$. Surface superconductivity is robust under pressure as demonstrated by the large superconducting screening signal that persists for applied dc-fields $H_a>H_c$. Surprisingly, for $p\ge 1.41$ GPa the superconducting transition temperature at the surface $T_c^S$ is larger than $T_c$ of the bulk. Therefore surface superconductivity may possibly have a non-trivial nature and is connected to the topological surface states detected by ARPES. 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.

arXiv commentmanuscript 9 pages with 8 figures + supplemental material 3 pages with 6 figures

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• Enhanced Superconductivity in the Se-substituted 1T-PdTe${}_2$
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• Anomalous charge transport of superconducting Cu${}_x$PdTe${}_2$ under high pressure
• Superconducting and structural properties of the type-I superconductor PdTe2 under high pressure
• Heat capacity of type I superconductivity in the Dirac semimetal PdTe${}_2$
• Scattering rate collapse driven by a van Hove singularity in the Dirac semi-metal PdTe${}_2$
• Disorder induced transition from type-I to type-II superconductivity in the Dirac semimetal PdTe${}_2$
• Type-II superconductivity in the Dirac semimetal PdTe2