PHOTOELECTRON SPECTROSCOPIC STUDY OF (Y1-XCAX)BAICU4OY - OBSERVATION OF THE FERMI-EDGE-LIKE STRUCTURE AT ROOM-TEMPERATURE

A photoelectron spectroscopic study of superconducting (Y1-xCax)Ba2Cu4Oy (x=0.0, 0.05, and 0.10) was performed. The observation of the Fermi-edge-like structure of this material is reported here. In the photoelectron spectrum, a clear edge at the Fermi energy was observed even at room temperature (normal state) for all samples, indicating that the surfaces of these materials were stable and surface degradation due to oxygen loss seemed to be negligible in vacuum. This is consistent with the fact that (Y1-xCax)Ba2Cu4Oy has an excellent thermal stability in oxygen content up to high temperature in air. © 1990 The American Physical Society.