Nodal gap structure in the noncentrosymmetric superconductor LaNiC 2 from magnetic-penetration-depth measurements

Abstract

We report measurements of the temperature dependence of the magnetic penetration depth in different-quality polycrystalline samples of noncentrosymmetric LaNiC 2 down to 0.05 K. This compound has no magnetic phases and breaks time-reversal symmetry. In our highest-quality sample, we observe a T 2 dependence below 0.4T c, indicative of nodes in the energy gap.We argue that previous results suggesting conventional s-wave behavior may have been affected by magnetic impurities. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.