Influence on superconductivity in the parity mixing superconductor Li ₂T₃B(T:Pt,Pd) by non-magnetic impurity and defect doping

Superconductors with noncentrosymmetric crystal structures such as Li ₂T₃B(T:Pd,Pt) have been the focus of in-depth research with their parity mixing nature. In this study, we focused our research on non-magnetic impurity effect in Li₂T₃B(T:Pd,Pt). The nature of the pair breaking by non-magnetic impurity in the parity mixing superconducting state is still unclear. We prepared different quality samples of Li₂Pd₃B and Li₂Pt₃B by changing conditions in synthesizing, and sample qualities were estimated by residual resistivity. Spin singlet dominant superconductor Li₂Pd₃B exhibits the weak T_c suppression attributed by non-magnetic impurity and defects, while H_c2 (0) value increased. This behavior is similar in ordinary s-wave superconductor. On the other hand, for the spin triplet dominant superconductor Li₂Pt₃B, it was suggested that the Cooper pair was broken and superconducting gap was decreased by non-magnetic impurities and defects. Li₂Pt₃B is similar to unconventional superconducting state.