SURFACE OPTIMIZATION OF RBa2Cu3O7-δ(R=Y, Nd) EPITAXIAL HIGH Tc FILMS FOR IN SITU PHOTOEMISSION STUDIES

Abstract

One of the intrinsic difficulties for in situ photoemission studies of high Tc oxide films is the surface volatility, especially the oxygen loss. In order to solve this problem, we have constructed a dedicated system for high Tc film surface studies, in particular for ARPES measurements. Here we briefly describe our pulsed laser deposition (PLD) system that is linked to the photoemission chamber at the Synchrotron Radiation Center (SRC) in Wisconsin, and discuss crystallographic and electronic properties measured on epitaxial YBa 2 Cu 3 O 7-δ (YBCO) and NdBa 2 Cu 3 O 7-δ (NBCO) films. Resistivity and XRD studies show that the best c axis epitaxial films, with Tc (onset)=92 K (Tc0=90.5 K ), are monophase and single crystalline with crystal coherence up to almost 1 μm. Initial core level photoemission study indicates that, for YBCO on SrTiO 3 (without any buffer layer), the Ba oxide layer tends to be the dominant surface layer. Further experiments are underway to reproducibly detect sharp Fermi edge and perform ARPES study on optimally doped film surfaces.