Change of the Surface Structure by F Doping in BiS2-Based Superconductor CeO1-xFxBiS2

The observation of the surface structure on single crystalline CeO1-xFxBiS2 (x = 0.5, and 0.7) was performed successfully using a scanning tunneling microscopy. In the sample with x = 0.5, the square lattice composed of Bi atoms was observed. In addition, defects of the surface atoms and streaks were detected on the surface as in the case of NdO0.7F0.3BiS2 single crystal. With further F doping, the surface structure of sample with x = 0.7 showed a novel structure, termed by the “bone” structure. This result suggests that the F concentration affects the surface structure.