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Electron irradiation reveals robust fully gapped superconductivity in LaNiGa2

S. Ghimire, K. R. Joshi, E. H. Krenkel, M. A. Tanatar, Yunshu Shi, M. Kończykowski, R. Grasset, V. Taufour, P. P. Orth, M. S. Scheurer, R. Prozorov

DOI 10.1103/PhysRevB.109.024515 · Physical Review B

T1

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Abstract

The effects of 2.5-MeV electron irradiation were studied in the superconducting phase of single crystals of LaNiGa2, 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 LaNiGa2, which does not break time-reversal symmetry. We discuss how our findings could be reconciled with previous measurements that indicated magnetic signatures in the superconducting phase.

Source-reported materials — not catalogue approval

FormulaReported Tc (K)Pressure (GPa)Type
LaNiGa2

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2Pressure not reportedonset
LaNiGa2

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2.08Pressure not reportedunknown

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