Soft x-ray photoemission study of new BiS₂-layered superconductor LaO_1-xF_xBiS₂

We use core level and valence band soft X-ray photoemission spectroscopy (SXPES) to investigate the electronic structure of new BiS2 layered superconductor LaO_1-xFxBiS₂. The core level spectra of doped samples show a new spectral feature on the lower binding energy side of the Bi 4f main peak, which may be explained by core-hole screening with metallic states near the Fermi level (E_F). The experimental electronic structure and its x dependence (a higher binding energy shift of the valence band as well as appearance of new states near E_F having the dominant Bi 6p character) were found to be consistent with the predictions of band structure calculations in general. Noticeable deviation of the spectral shape of the states near E_F from that of calculations might provide insight into interesting physical properties. This study provides the first experimental electronic structure of the new BiS₂ layered superconductors.