High-resolution magnetic penetration depth and inhomogeneities in locally noncentrosymmetric SrPtAs

TL;DR

This study investigates the magnetic penetration depth and inhomogeneities in SrPtAs, revealing a nodeless isotropic superconducting gap and providing insights into its pairing mechanism and order parameter symmetry.

Contribution

It provides the first detailed magnetic penetration depth measurements on SrPtAs, demonstrating intrinsic s-wave behavior and constraining theoretical models of its superconductivity.

Findings

SrPtAs exhibits a nodeless isotropic superconducting gap.

Polycrystalline samples show intrinsic s-wave BCS behavior.

Granular samples reveal intergrain coupling effects.

Abstract

We present a magnetic-penetration-depth study on polycrystalline and granular samples of SrPtAs, a pnictide superconductor with a hexagonal structure containing PtAs layers that individually break inversion symmetry (local noncentrosymmetry). Compact samples show a clear-cut s-wave-type BCS behavior, which we consider to be the intrinsic penetration depth of SrPtAs. Granular samples display a sample-dependent second diamagnetic drop, attributed to the intergrain coupling. Our experimental results point to a nodeless isotropic superconducting energy gap in SrPtAs, which puts strong constraints on the driven mechanism for superconductivity and the order parameter symmetry of this compound.