Probing the superconducting gap symmetry of PrRu$_{4}$Sb$_{12}$: A comparison with PrOs$_{4}$Sb$_{12}$

TL;DR

This study investigates the superconducting gap symmetry of PrRu$_{4}$Sb$_{12}$ through magnetic penetration depth measurements, revealing a fully-gapped, moderate-coupling superconducting state and comparing it with PrOs$_{4}$Sb$_{12}$.

Contribution

The paper provides the first detailed measurement of the magnetic penetration depth in PrRu$_{4}$Sb$_{12}$, demonstrating its fully-gapped superconducting nature and comparing it with related compounds.

Findings

PrRu$_{4}$Sb$_{12}$ exhibits exponential behavior in penetration depth below 0.5$T_c$.

The superconducting gap ratio $rac{ ext{Δ}(0)}{k_B T_c}$ is 1.9.

The superfluid density and gap parameters are consistent with a moderate-coupling, fully-gapped superconductor.

Abstract

We report measurements of the magnetic penetration depth $\lambda$ in single crystals of PrRu$_{4}$Sb$_{12}$ down to 0.1 K. Both $\lambda$ and superfluid density $\rho_{s}$ exhibit an exponential behavior for $T$ $<$ 0.5$T_{c}$, with parameters $\Delta$(0)/\textit{k}$_{B}$\textit{T}$_{c}$ = 1.9 and $\lambda(0)$ = 2900 \AA. The value of $\Delta$(0) is consistent with the specific-heat jump value of $\Delta C/\gamma T_{c}$ = 1.87 measured elsewhere, while the value of $\lambda(0)$ is consistent with the measured value of the electronic heat-capacity coefficient $\gamma$. Our data are consistent with PrRu$_{4}$Sb$_{12}$ being a moderate-coupling, fully-gapped superconductor. We suggest experiments to study how the nature of the superconducting state evolves with increasing Ru substitution for Os.