SURFACE AND INTERFACE STUDY ON MBE-GROWN ND1.85CE0.15CUO4 THIN-FILMS BY PHOTOEMISSION SPECTROSCOPY AND TUNNELING SPECTROSCOPY

Nd1.85Ce0.15CuO4 (NCCO) surfaces and Pb/NCCO interfaces have been exte nsively investigated by X-ray/ultraviolet spectroscopies and tunnel sp ectroscopy using films grown by MBE. The photoelectron spectra obtaine d in-situ on the surfaces of MBE-grown NCCO films are free from any di rt peak, and make feasible the first systematic investigation of the s urface and interface of cuprates. The results indicate that the surfac e and interface electronic structures of NCCO are strongly influenced by oxygen non-stoichiometry, and that the precise control of oxygen co ntent at the surface (interface) is essential to obtain the bulk-repre sentative surface (interface).