Abstract
Pb-substituted La(O, F)BiS(2) (Pb-LaOFBiS(2)) exhibits improved superconducting properties and a resistivity anomaly around 100 K that is attributed to a structural transition. We have performed temperature(T)-dependent photoelectron holography (PEH) to study dopant incorporation sites and the local structure change across the anomaly. The PEH study of Pb-LaOFBiS(2) provided evidence for the dominant incorporation sites of Pb and F: Pb atoms are incorporated into the Bi sites and F atoms are incorporated into the O site. No remarkable difference in the local structures around Pb and Bi atoms was observed. Across the temperature of the resistivity anomaly (T(*)), photoelectron holograms of Bi 4f changed. Comparisons of holograms with those of non-substituted LaOFBiS(2) sample, as well as simulated holograms, suggested that (1), above T(*), the tetragonal structure of Pb-LaOFBiS(2) is different from the tetragonal structure of LaOFBiS(2) and (2), below T(*), the tetragonal structure still remains in Pb-LaOFBiS(2). We discuss a possible origin of the difference in the structure above T(*) and the implication of the result below T(*), which are necessary ingredients to understand the physical properties of Pb-LaOFBiS(2).