Investigation of Superconductivity in Ce-Doped (La,Pr)OBiS₂ Single Crystals

Single crystals of Ce-doped (La,Pr)OBiS₂ superconductors, the multinary rare-earth elements substituted ROBiS₂, were successfully grown. The grown crystals typically had a size of 1-2 mm and a plate-like shape with a well-developed c-plane. The c-axis lattice constants of the obtained (La,Ce,Pr)OBiS₂ single crystals were approximately 13.6-13.7 Å, and the superconducting transition temperature was 1.23-2.18 K. Valence fluctuations of Ce and Pr were detected through X-ray absorption spectroscopy analysis. In contrast to (Ce,Pr)OBiS₂ and (La,Ce)OBiS₂, the superconducting transition temperature of (La,Ce,Pr)OBiS₂ increased with the increasing concentrations of the tetravalent state at the R-site.