On detection of the Fermi edge in in situ grown thin films of high-T-c oxides

We discuss our systematic series of experiments on the photoelectric detection of the Fermi edge using a cylindrical mirror analyser on films of high-T-c oxides. grown in situ by pulsed laser ablation. The Fermi edge (comparable to the edge of the reference Ag) is very easily observed even in the two-phase BSCCO-2212 film that exhibits onsets of superconducting transitions, at 85 and 45 K. In contrast, the Fermi edge is weaker and more difficult to observe even in the state-of-the-art. highly epitaxial, monophase YBa2Cu3O7-y (YBCO) and NdBa2Cu3O7-y. (NBCO-123) films (both with T-c = 92 K). So far we could not detect the Fermi edge in the films of the double-'chain' YBCO-124. (C) 2001 Elsevier Science B.V. All rights reserved.