Experimental Investigation of Electronic Structure of La(O,F)BiSe2**Supported by the National Basic Research Program of China under Grant Nos 2015CB921300, 2013CB921700 and 2016YFA0300404, the National Natural Science Foundation of China under Grant Nos 11474340, 11234014, U1532267 and 11674327, and the Chinese Academy of Sciences under Grant No XDB07000000.

Abstract

La(O,F)BiSe2 is a layered superconductor and has the same crystal structure with La(O,F)BiS2. We investigate the electronic structure of La(O,F)BiSe2 using the angle-resolved photoemission spectroscopy. Two electron-like Fermi surfaces around X(π, 0) are observed, corresponding to the electron doping of 0.23 per Bi site. We clearly resolve anisotropic band splitting along both Γ—X and M—X due to the cooperative effects of large spin-orbit coupling and interlayer coupling. Moreover, we observe an almost non-dispersive electronic state around −0.2eV between the electron-like bands. This state vanishes after in-situ K evaporation, indicating that it could be the localized surface state caused by defects on the cleaved surface.