Magnetic response of noncentrosymmetric superconductor La2C3: Effect of double-gap and spin-orbit interaction

TL;DR

This study investigates the magnetic properties of the noncentrosymmetric superconductor La2C3, revealing the effects of spin-orbit interaction and double-gap structure through muon spin rotation measurements.

Contribution

It provides experimental evidence of spin-orbit interaction and a double-gap structure in La2C3, highlighting their influence on its superconducting properties.

Findings

Muon spin rotation shows field-induced weak depolarization indicating spin-orbit interaction.

Superfluid density is more reduced at lower fields, consistent with a secondary energy gap.

Field dependence of muon spin relaxation supports the presence of a double-gap structure.

Abstract

The presence of spin-orbit (SO) interaction in a noncentrosymmetric superconductor, La2C3 (T_c~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 (sigma_v) exhibits a field dependence that is characterized by a kink, where sigma_v (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 sigma_v, and also consistent with the possible influence of asymmetric deformation of the Fermi surface due to the SO interaction.