Strong orbital-dependent d-band hybridization and Fermi-surface reconstruction in metallic Ca2-xSrxRuO4.

We study the effects of RuO6 rotation on Ru 4d band structures in metallic Ca2-xSrxRuO4 (0.5 < or = x < or = 2) by first-principles electronic structure calculations. We show that the RuO6 rotation leads to the strong hybridization between dxy and dx2-y2 bands, resulting in orbital-dependent changes in the band structure. The dxy band near the Fermi level is significantly modified and thereby a severely reconstructed Fermi surface with nested sections appears at x=0.5. In contrast, the dyz and dzx bands are found to be insensitive to the rotational distortions induced by the Ca substitution. Our results imply that the progressive changes in the magnetic, optical, and thermal properties of Ca2-xSrxRuO4 are associated with the dxy band.