Photoemission study of weakly magnetic Y(Co1-xAlx)(2)

We have studied the electronic structure of Y(Co1-xAlx)(2) with x = 0.0, 0. 12, and 0.18, which compositions cover the paramagnetic, metamagnetic, and ferromagnetic phases, by means of photoemission and inverse-photoemission s pectroscopy. With Al substitution, broad peaks near the Fermi level (EF) ar e shifted upwards and one of them crosses EF as predicted by band-structure calculation, although the peaks art: much broader than predicted by the ca lculation. The overall Co 3d band is narrow and has a high binding energy t ail compared to the band-structure calculation, indicating significant elec tron correlation effects in the Co 3d band. In order to explain these obser vations, model self-energy corrections have been applied to the band densit y of states. The lower energy scale of the self-energy is found to lie in t he same range as the characteristic temperature of the magnetic susceptibil ity.[S0163-1829(99)09725-8].