PHOTOEMISSION-STUDIES OF OXIDE SUPERCONDUCTORS

A procedure has been developed for preparation of clean surfaces of oxide superconductors for study by electron spectroscopy. This involves annealing, ceramic or thin films samples under an oxygen atmosphere in a preparation chamber that is an integral part of the spectrometer UHV system. The technique has allowed the authors to obtain high quality spectroscopic data from YBa2Cu3O7-x, Bi2Sr2Can-1CunO4+2n (n=2, 3) and La2-xSrxCuO4. The results are considered in relation to other contemporary work. Current areas of controversy are highlighted, including a discussion of Fermi edge and satellite structure in valence region spectra and evidence for mixed valency in Cu:2p and O:1s core regions. © 1990 IOP Publishing Ltd.