Electron irradiation reveals robust fully gapped superconductivity in LaNiGa${}_2$

Abstract

The effects of 2.5 MeV electron irradiation were studied in the superconducting phase of single crystals of LaNiGa${}_2$, using measurements of electrical transport and radio-frequency magnetic susceptibility. The London penetration depth is found to vary exponentially with temperature, suggesting a fully gapped Fermi surface. The inferred superfluid density is close to that of a single-gap weak-coupling isotropic $s-$wave superconductor. Superconductivity is extremely robust against nonmagnetic point-like disorder induced by electron irradiation. Our results place strong constraints on the previously proposed triplet pairing state by requiring fine-tuned impurity scattering amplitudes and are most naturally explained by a sign-preserving, weak-coupling, and approximately momentum independent singlet superconducting state in LaNiGa${}_2$, which does not break time-reversal symmetry. We discuss how our findings could be reconciled with previous measurements indicating magnetic moments in the superconducting phase.

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Cited by in corpus (4)

• Disorder-induced suppression of superconductivity in infinite-layer nickelates
• Pressure induced superconducting dome in LaNiGa2
• Observation of a pronounced Hebel-Slichter peak in the spin-lattice relaxation rate and implications for gap and pairing symmetry in LaNiGa${}_2$
• Single-gap Isotropic $s-$wave Superconductivity in Single Crystals ${\text{AuSn}}_4$