Evidence for two energy gaps and Fermi liquid behavior in SrPt$_2$As$_2$ superconductor

TL;DR

This study reveals SrPt2As2 exhibits two distinct superconducting energy gaps and Fermi liquid behavior, supported by calorimetric and NMR measurements, indicating complex superconducting and electronic properties.

Contribution

First detailed calorimetric and NMR analysis showing two-gap superconductivity and Fermi liquid behavior in SrPt2As2.

Findings

Two energy gaps associated with superconductivity.

Fermi liquid ground state confirmed by NMR and resistivity.

Electronic specific heat shows two linear components.

Abstract

We report a detailed calorimetric study on single crystals of the 5$d$-transition metal pnictide SrPt2As2 with a superconducting critical temperature $T_c$ $\sim$5K. The peculiar field dependence of the electronic specific heat coefficient $\gamma$ can be decomposed into two linear components. Moreover, the temperature evolution of the electronic specific heat below $T_c$ is best described by a two-gap model. These findings suggest that two energy gaps are associated with the superconductivity. In parallel, we show that the spin-lattice relaxation time $T_1$, through nuclear magnetic resonance measurement, obeys the so-called Korringa relation well. This, along with the $T^2$ dependence of resistivity at low temperatures, points to a Fermi liquid ground state in this material.