Single gap s-wave superconductivity in Nb2PdS5

•In this paper, we report on pairing symmetry and superconducting gap in recently discovered superconductor Nb2PdS5.•This is a remarkable superconductor with highest ever reported Hc2/Tc ratio of ∼3.•In some theoretical studies, such effects have been ascribed to multiband effects and possible p-wave superconductivity.•However our penetration depth data is well ascribed to a single gap nodeless S-wave superconductivity.

Superconducting order parameter and its symmetry are important parameters towards deciphering the pairing mechanism in newly discovered superconducting systems. We report a study on penetration depth measurement on Nb2PdS5 that has recently been reported with extremely high upper critical field with possible triplet pairing mechanism. Our data show that at low temperatures the change in penetration depth Δλ is best fitted with BCS s-wave model for single gap with zero-temperature value of the superconducting energy gap Δ0 = 1.05 meV, corresponding to the ratio 2Δ0/kBTc = 3.9 ± 0.18. The superfluid density in the entire temperature range is well described by single gap with gap ratio 2Δ0/kBTc = 4.1 ± 0.13 for λ(0) = 225 nm.