Anomalous charge transport of superconducting Cu$_{x}$PdTe$_2$ under high pressure

TL;DR

This study reveals unconventional T^4 resistivity behavior in Cu$_x$PdTe$_2$ under high pressure, linked to low carrier density and strong electron-phonon coupling, with implications for understanding charge transport in topological superconductors.

Contribution

It provides the first detailed high-pressure resistivity analysis of Cu$_x$PdTe$_2$, highlighting stable anomalous resistivity and quantifying electron-phonon coupling in a topological superconductor.

Findings

Resistivity follows a T^4 law up to 40 K, stable under pressure.

Low carrier density reduces electron-phonon scattering region.

Electron-phonon coupling constant $bb_{tr} = 1.2$ at ambient pressure.

Abstract

By means of high-pressure resistivity measurements on single crystals, we investigate the charge transport properties of Cu$_x$PdTe$_2$, notable for the combination of topological type-II Dirac semimetallic properties with superconductivity up to $T_c = 2.5$ K. In both cases of pristine ($x = 0$) and intercalated ($x=0.05$) samples, we find an unconventional $T^4$ power law behavior of the low-temperature resistivity visible up to $\sim$40 K and remarkably stable under pressure up to 8.2 GPa. This observation is explained by the low carrier density $n$, which strongly reduces the $k$-region available for electron-phonon scattering, as previously reported in other low-$n$ two-dimensional systems, such as multilayer graphene and semiconductor heterostructures. Our data analysis complemented by specific heat measurements and supported by previous quantum oscillation studies and \textit{ab initio} calculations suggests a scenario of one-band charge transport. Within this scenario, our analysis yields a large value of transport electron-phonon coupling constant $\lambda_{tr} = 1.2$ at ambient pressure that appears to be strongly enhanced by pressure assuming a constant effective mass.