Fermi surface of Sr2RuO4 from angle resolved photoemission

We investigated the low-energy electronic structure of Sr2RuO4 by angle-res olved photoemission spectroscopy (ARPES) focusing, in particular, on the co ntroversial issues of the Fermi surface (FS) topology and of the extended v an Hove singularity (evHs). A. detailed study of temperature and photon ene rgy dependence demonstrates the surface-state nature of the electronic band responsible for the evils, and may suggest the presence of ferromagnetic c orrelations at the surface. In addition, we detected a replica of the prima ry FS that indicates a root2 x root2 surface reconstruction, as confirmed b y LEED. In light of these findings, the FS determined by ARPES is consisten t with LDA and de Haas-van Alphen (dHvA) results, and it provides additiona l information on the detailed shape of the alpha, beta and gamma sheets. Al so, 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 Fer mi liquid behavior in our ARPES measurements for T < 130 K. <(c)> 2001 Else vier Science B.V. All rights reserved.