Photoemission Study of Superconducting Ba0.6K0.4BiO3

Photoelectron spectra of a [110]-oriented epitaxial thin film of Ba0.6K0.4BiO3 have been studied by use of the synchrotron radiation to elucidate its electronic structure. Observed spectra shows a clear Fermi edge and agree with published band calculations. A normal emission study for the (110) surface shows a band crossing the Fermi level between the M and Γ points, which is assigned to the Bi-O sp orbital.