Evidence for two-gap superconductivity in the non-centrosymmetric compound LaNiC2

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We study the superconducting properties of the non-centrosymmetric compound LaNiC 2 by measuring the London penetration depth Δλ( T ), the specific heat C ( T , B ) and the electrical resistivity ρ ( T , B ). Both Δ λ ( T ) and the electronic specific heat C e ( T ) exhibit behavior at low temperatures that can be described in terms of a phenomenological two-gap Bardeen–Cooper–Schrieffer (BCS) model. The residual Sommerfeld coefficient in the superconducting state, γ 0 ( B ), shows a rapid increase at low fields and then an eventual saturation with increasing magnetic field. A pronounced upturn curvature is observed in the upper critical field B c2 ( T ) near T c . All these experimental observations support the existence of two-gap superconductivity in LaNiC 2 .