Growth and superconducting properties of F-substituted ROBiS2 (R=La, Ce, Nd) single crystals

• We have grown RO(F)BiS2 surconducting single crystals using CsCl/KCl flux.
• We have measured the intrinsic properties of RO(F)BiS2 superconductors.
• We examined F compositions dependence on the properties in the single crystals.

F-substituted ROBiS2 (R=La, Ce, Nd) superconducting single crystals with different F concentrations were grown successfully using a CsCl/KCl flux. All crystals produced had a plate-like shape, with a well-developed ab-plane 1–2 mm in size. Electron probe microanalysis did not detect any Cs, K, or Cl flux components in the crystals. As-grown single crystals of F-substituted LaOBiS2 and CeOBiS2 exhibited superconductivity at about 3 K, whereas F-substituted NdOBiS2 was superconductive at approximately 5 K. The superconducting anisotropy of single crystal F-substituted LaOBiS2 and NdOBiS2 was estimated to be 30–45 according to the effective mass model, whereas the anisotropy for F-substituted CeOBiS2 single crystals was 13–21. The F-substituted CeOBiS2 single crystals exhibited a magnetic order around 7 K that apparently coexisted with superconductivity below approximately 3 K.