Nodeless superconductivity in noncentrosymmetric LaRhSn

TL;DR

This study reveals that LaRhSn exhibits fully gapped, nodeless superconductivity with no evidence of time-reversal-symmetry breaking, confirmed through specific heat, $bc$SR, and TDO measurements.

Contribution

It provides the first comprehensive experimental evidence of nodeless, s-wave superconductivity in noncentrosymmetric LaRhSn using multiple low-temperature techniques.

Findings

LaRhSn shows exponential temperature dependence of specific heat and penetration depth.

Superconductivity in LaRhSn is consistent with a single-gap s-wave model.

No evidence of time-reversal-symmetry breaking was observed in LaRhSn.

Abstract

The superconducting order parameter of the noncentrosymmetric superconductor LaRhSn is investigated by means of low temperature measurements of the specific heat, muon-spin relaxation/rotation ($\mu$SR) and the tunnel-diode oscillator (TDO) based method. The specific heat and magnetic penetration depth [$\lambda(T)$] show an exponentially activated temperature dependence, demonstrating fully gapped superconductivity in LaRhSn. The temperature dependence of $\lambda^{-2}(T)$ deduced from the TDO based method and $\mu$SR show nearly identical behavior, which can be well described by a single-gap $s$-wave model, with a zero temperature gap value of $\Delta(0)=1.77(4)k_BT_c$. The zero-field $\mu$SR spectra do not show detectable changes upon cooling below $T_c$, and therefore there is no evidence for time-reversal-symmetry breaking in the superconducting state.