Magnetic impurity effects on the superconductivity of noncentrosymmetric LaNiC2: Ce substitution for la

Abstract

Effects of paramagnetic impurities on the superconducting transition of noncentrosymmetric LaNiC2 have been studied by Ce substitution for La up to 3 at.%. With the substitution the superconducting transition temperature Tc∼2.8 K of the pure system decreases dramatically, and disappears with Ce just above 2 at.%. This intense suppression of Tc with the Ce substitution can be explained by the Abrikosov-Gor'kov theory for conventional s-wave superconductors with localized magnetic moments. These results, together with a quite small depression of Tc with nonmagnetic Y impurities, strongly suggest that LaNiC2 is a BCS superconductor with a full superconducting energy gap, not an unconventional one with a nodal gap.