Electronic structure and magnetism of Sr3Ru2O7 -: art. no. 165101

The electronic structure of layered Sr3Ru2O7 in its orthorhombic structure is investigated using density functional calculations. The band structure near the Fermi energy, consists of Ru t(2g) states hybridized with O p orbitals. The gz and st bands, which are largely responsible for the nesting related antiferromagnetic spin fluctuations in Sr(2)Ru4 split pairwise into even and odd combinations due to the interlayer coupling reducing the strength of the nesting. The xy bands show much less interplanar coupling as expected, and also less c-axis dispersion, so that the barrel-like sections are largely intact compared to the single layer material. The zone folding due to orthorhombicity yields small cylindrical lens shaped Fermi surfaces centered at the midpoints of the former tetragonal Gamma -X lines. Fixed spin moment calculations indicate that tetragonal Sr3Ru2O7 is borderline ferromagnetic but that orthorhombicity favors magnetism via a substantial magnetoelastic coupling. These results are related to experimental observations particularly in regard to magnetic properties.