Superconductivity at 5.4 K in $\beta$-Bi$_2$Pd

TL;DR

This study confirms bulk superconductivity in high-quality $eta$-Bi$_2$Pd single crystals below 5.4 K, revealing it as a multiple-band/multiple-gap superconductor through various measurements.

Contribution

It provides detailed experimental evidence of superconductivity in $eta$-Bi$_2$Pd and identifies its multi-gap nature, which was not previously established.

Findings

Superconductivity observed below 5.4 K in $eta$-Bi$_2$Pd

Material exhibits multiple-band/multiple-gap superconductivity

Electrical resistivity shows convex-upward behavior at high temperatures

Abstract

We investigate bulk superconductivity in a high-quality single crystal of Bi$_2$Pd ($\beta$-Bi$_2$Pd, space group; I4/mmm) at temperatures less than 5.4 K by exploring its electrical resistivity, magnetic susceptibility, and specific heat. The temperature dependence of the electrical resistivity shows convex-upward behaviors at temperatures greater than 40-50 K, which can be explained by a parallel-resistor model. In addition, we demonstrate that this material is a multiple-band/multiple-gap superconductor based on the temperature dependences of the specific heat and the upper critical field.