ELECTRONIC-STRUCTURE AND YB-VALENCE IN THE KONDO LATTICES YBCU(4)M (M=AG, AU, PD, IN)

Optical reflectivity measurements over a wide spectral range and at di fferent temperatures together with self consistent electronic FLAPW ca lculations within LDA have been used to investigate the electronic str ucture of the compounds. A remarkable agreement between theory and exp eriment has been found which allows for an interpretation of the origi n of the different degree of f-d hybridization in these Yb-based mater ials.