Magnetic response of noncentrosymmetric superconductor La2C3: Effect of double-gap and spin-orbit interaction
Abstract
The presence of spin-orbit (SO) interaction in a noncentrosymmetric superconductor, La2C3 (Tc~11 K) is demonstrated by muon spin rotation (muSR) in its normal state, where muSR spectra exhibit field-induced weak depolarization due to van Vleck-like local susceptibility. In the mixed state, muon spin relaxation due to inhomogeneity of internal field (sigmav) exhibits a field dependence that is characterized by a kink, where sigmav (and hence the superfluid density) is more strongly reduced at lower fields. This is perfectly in line with the presence of a secondary energy gap previously inferred from the temperature dependence of sigmav, and also consistent with the possible influence of asymmetric deformation of the Fermi surface due to the SO interaction.