Multiband superconductivity in PrPt4Ge12 single crystals

TL;DR

This study investigates the superconducting properties of PrPt4Ge12 single crystals, revealing evidence of multiband superconductivity through measurements of penetration depth and specific heat that deviate from conventional models.

Contribution

The paper provides the first detailed experimental evidence of multiband superconductivity in PrPt4Ge12 using penetration depth and specific heat measurements.

Findings

Weak temperature dependence of $ ho_s(T)$ and $C_e(T)$ at low T

Deviations from conventional s-wave and nodal superconductivity

Data consistent with a two-gap superconducting model

Abstract

We report measurements of the London penetration depth $\Delta\lambda(T)$ and the electronic specific heat $C_e(T)$ on high-quality single crystals of the filled-skutterudite superconductor PrPt$_4$Ge$_{12}$ ($T_c\simeq$8K). Both quantities show a weak temperature dependence at $T\ll T_c$, following $\Delta\lambda\sim T^n$ ($n\simeq 3.2$) and $C_e/T\sim T^{2.8}$. Such temperature dependences deviate from both conventional s-wave type and nodal superconductivity. A detailed analysis indicates that the superfluid density $\rho_s(T)$, derived from the penetration depth, as well as the electronic specific heat can be consistently described in terms of a two-gap model, providing strong evidence of multiband superconductivity for PrPt$_4$Ge$_{12}$.