Unveiling the Superconducting Ground State of Heusler alloy Pd2ZrIn via muon spin relaxation and rotation measurement

TL;DR

This study investigates the superconducting properties of Pd2ZrIn, revealing it as a conventional, weakly coupled, type-II superconductor with a fully gapped s-wave order parameter and preserved time-reversal symmetry.

Contribution

The paper provides the first muon spin relaxation and rotation measurements confirming the superconducting ground state and symmetry properties of Pd2ZrIn.

Findings

Pd2ZrIn exhibits bulk type-II superconductivity with T_C ~ 2.2 K.

Muon measurements show no evidence of spontaneous magnetic fields below T_C.

The superconducting gap is fully gapped and nodeless, consistent with s-wave pairing.

Abstract

Full Heusler alloys XInPd2 (X= Zr, Hf and Ti) have recently attracted significant attention owing to their symmetry-driven electronic structure and also due to the interplay between disorder and emergent ground states. Within this family, Pd2ZrIn serves as a unique platform to study the effect of disorder on superconducting pairing. This alloy crystallizes in a cubic L21 structure with significant B2-type antisite disorder. Electrical resistivity and magnetic susceptibility studies confirm bulk type-II superconductivity with a transition temperature TC ~ 2.2 K. Zero-field {\mu}SR results reveal no evidence of spontaneous internal magnetic fields below TC, confirming the preservation of time-reversal symmetry. Transverse-field {\mu}SR spectra show the formation of a vortex lattice, consistent with type-II superconductivity, and the superfluid density is well described by a fully gapped, nodeless s-wave state with superconducting gap {\Delta} (0) ~ 0.33 \pm 0.01 meV. Furthermore, the estimated ratio of transition temperature and Fermi temperature (TC/TF) indicates that this alloy lies within the conventional superconducting regime on the Uemura plot. These results establish Pd2ZrIn as a weakly coupled, dirty-limit, type-II superconductor; with a fully gapped, nodeless order parameter and preserved time-reversal symmetry.