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

We study the superconducting properties of the noncentrosymmetric compound LaNiC2 by measuring the London penetration depth 1k(T ), the specific heat C(T, B) and the electrical resistivity ρ(T, B). Both 1λ(T ) and the electronic specific heat Ce(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, γ0(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 Bc2(T ) near Tc. All these experimental observations support the existence of two-gap superconductivity in LaNiC2. 3 Author to whom any correspondence should be addressed. Content from this work may be used under the terms of the Creative Commons Attribution-NonCommercialShareAlike 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. New Journal of Physics 15 (2013) 053005 1367-2630/13/053005+16$33.00 © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft