A μSR determination of the penetration depth in superconducting YNi2B2C

Muon spin rotation (μSR) and magnetisation measurements have been used to characterise the superconducting state of YNi 2 B 2 C below T c = 15 K . A measured B c2 (0) of 6.0(5) T and B c1 (0) of 36.9(5) mT from magnetisation measurements, together with the μSR measurements, provide a coherence length, ξ(0), of 8.1 nm and a magnetic penetration depth, λ(0), of 103 nm. The temperature dependence of the penetration depth deduced from the μSR measurements is consistent with the BCS model and implies conventional s wave pairing in YNi 2 B 2 C. Using these results together with existing thermodynamic data we estimate a superconducting carrier density of 1.9 per formula unit and an electron-mass enhancement factor of 9.4.