  We investigated the low-energy electronic structure of Sr2RuO4 by
angle-resolved photoemission spectroscopy (ARPES) focusing, in particular, on
the controversial issues of the Fermi surface (FS) topology and of the extended
van Hove singularity (evHs). A detailed study of temperature and photon energy
dependence demonstrates the surface-state nature of the electronic band
responsible for the evHs, and may suggest the presence of ferromagnetic
correlations at the surface. In addition, we detected a replica of the primary
FS that indicates a (sqrt2 x sqrt2) surface reconstruction, as confirmed by
LEED. In light of these findings, the FS determined by ARPES is consistent with
LDA and de Haas-van Alphen (dHvA) results, and it provides additional
information on the detailed shape of the alpha, beta and gamma sheets. Also, at
this stage, because of the strong sensitivity of the cleaved surface, we could
not find any robust signature of the crossover from 2D to 3D Fermi liquid
behavior in our ARPES measurements for T<130 K.
