Probing the superconducting state of the Heusler supercoductor: ZrNi$_2$Ga

TL;DR

This study investigates the superconducting properties of ZrNi₂Ga using muon spin techniques, confirming an isotropic s-wave gap, measuring key parameters, and exploring flux lattice structures without evidence of time reversal symmetry breaking.

Contribution

The paper provides the first detailed muon spin rotation and relaxation analysis of ZrNi₂Ga, revealing its s-wave superconducting gap and flux lattice behavior.

Findings

Superconducting gap (1) meV consistent with BCS theory

Magnetic penetration depth (5) nm at zero temperature

Evidence of flux lattice crossover at low temperatures

Abstract

Using both muon spin rotation and muon spin relaxation, the superconducting ground state of the Heusler superconductor {ZrNi$_2$Ga} has been studied. The temperature dependence of the magnetic penetration depth of {ZrNi$_2$Ga} is consistent with a single isotropic gap s-wave BCS superconductor. The gap energy is \Delta(0)=0.44(1) meV and the magnetic penetration depth, \lambda(0), is 310(5) nm. Furthermore, we show evidence of a possible cross-over from an square flux line lattice to a hexagonal lattice at low temperatures. No evidence of time reversal symmetry breaking has been observed as might be expected for a half metal superconductor.