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].