ELECTRONIC BAND-STRUCTURE OF THE SUPERCONDUCTOR SR2RUO4

A local-density electronic-band-structure calculation was performed for a recently discovered non-copper-layered perovskite superconductor, Sr2RuO4. It was found that the electronic structure near the Fermi energy is essentially described by antibonding bands of the Ru d and O pπ states. Although two holes in the bands are predominantly situated in a d(xy)-pπ state in the ab plane, the hole occupations in the other d-pπ states vertical to the plane are not negligibly small, possibly in conjunction with the smallness of tetragonal distortion of the RuO6 octahedron. Associated with the antibonding d-pπ bands, the density of states at the Fermi energy is relatively high (4.36 states/eVcell) but not enough to account for the observed specific-heat constant γexp and temperature-independent magnetic susceptibility χexp. We found a large Stoner factor, which may explain most of the mass enhancement involved in χexp. Certain similarities and dissimilarities in the electronic properties to the cuprate superconductors are discussed. © 1995 The American Physical Society.