X-ray absorption near edge structure (XANES) spectra and x-ray magnetic cir
cular dichroism (XMCD) spectra at the Co K edge have been measured for Co c
lusters with the mean diameter d = 6-13 nm. The spectral analysis indicates
that the fee phase is predominant for d = 6 nm, while the hcp phase gradua
lly increases with increasing d in agreement with the results of transmissi
on electron microscopy. The 4p orbital moments of clusters tend to decrease
in the smaller cluster, but the reduction is small compared with the case
of the multilayers, suggesting the importance of surface effects of the Co
cluster system.