Multigap Superconductivity in Chiral Noncentrosymmetric TaRh$_{2}$B$_{2}$

TL;DR

This paper reports the discovery of multigap superconductivity in TaRh₂B₂, a bulk type-II superconductor with a transition temperature of 6 K, exhibiting two-gap behavior and high upper critical field exceeding the Pauli limit.

Contribution

The study provides the first evidence of multigap superconductivity in TaRh₂B₂ using muon spin relaxation and specific heat measurements, revealing its multiband nature and high critical field.

Findings

Superconducting transition temperature T_c = 6 K.

Observation of two-gap s+s-wave superconductivity.

Upper critical field exceeds the Pauli limit at 15.2 T.

Abstract

We report the first observation of multigap superconductivity in TaRh$_{2}$B$_{2}$. We show TaRh$_{2}$B$_{2}$ is a bulk type-II superconductor with a transition temperature, $T_{\mathrm{c}} = 6.00(5)$ K. We present transverse-field muon spin relaxation data where the superconducting gap can be fit using a two-gap $\left(s+s\right)$-wave model. We also report the zero-field electronic specific heat in the superconducting state that is best described by the same $\left(s+s\right)$ model providing further evidence of multiband behavior in this superconductor. Zero-field muon spin relaxation measurements show time-reversal symmetry is preserved in the superconducting state. We demonstrate that TaRh$_{2}$B$_{2}$ has an upper critical field of $15.2(1)$ T, which is significantly higher than previously reported and exceeds the Pauli limit.