Low-temperature magneto-thermal transport investigation of a Ni-based superconductor BaNi2As2: Evidence for fully gapped superconductivity

TL;DR

This study investigates the low-temperature thermal and specific heat properties of BaNi2As2, providing evidence that it is a fully gapped superconductor with conventional BCS behavior.

Contribution

It offers the first detailed low-temperature thermal and specific heat measurements of BaNi2As2, demonstrating fully gapped superconductivity through experimental evidence.

Findings

Thermal conductivity shows T-linear behavior in the normal state.

Exponential decrease of thermal conductivity below Tc consistent with BCS theory.

Specific heat data fit well with BCS temperature dependence.

Abstract

We have performed low-temperature specific heat and thermal conductivity measurements of the Ni-based superconductor BaNi$_2$As$_2$ ($T_\mathrm{c}$ = 0.7 K) in magnetic field. In zero field, thermal conductivity shows $T$-linear behavior in the normal state and exhibits a BCS-like exponential decrease below $T_\mathrm{c}$. The field dependence of the residual thermal conductivity extrapolated to zero temperature is indicative of a fully gapped superconductor. This conclusion is supported by the analysis of the specific heat data, which are well fit by the BCS temperature dependence from $T_\mathrm{c}$ down to the lowest temperature of 0.1 K.