Electronic structure of YNi1-xCuxBC studied by X-ray emission and photoelectron spectroscopy

Results of first measurements of X-ray emission spectra (Ni L alpha, Cu L alpha and B K alpha) and X-ray photoelectron spectra (valence band and core levels) of YNi1-xCuxBC (x = 0.1-0.55) are presented. It is found that Ni and Cu 3d-states have predominantly metallic character and provide the main contribution to the density of states at the Fermi level N(E-f) N(E-f) progressively increases with x and correlates well with the magnetic susceptibility measurements, accounting for the increase in T-c with copper doping. In Ni 2p(3/2) XPS a low intensity high-energy satellite peak is found which can be attributed to two-hole bound states. Selective oxidation of Y-atoms is found under exposure of the freshly cleaved surface of YNi0.6Cu0.4BC to air. (C) 1997 Elsevier Science Ltd.