Electronic structure of the pure and Ti-doped Sr2RuO4 superconductor obtained by the embedded cluster method

Abstract

Electronic structure of the pure and Ti-doped Sr2RuO4 superconductor is studied by the embedded cluster method at the Hartree-Fock (HF) and the second-order Møller-Plesset perturbation theory (MP2) electron correlation levels. The representative cluster was embedded into the Madelung potential that mimics a real crystal. The interatomic interaction leads to an effective electron transfer from O to Ru at both the HF and MP2 levels. At the MP2 level, we obtained the Ru charge equal to +1.57, instead of +4 in the formal valence (ionic) model. The eg level, which was assumed empty in most of the previous studies, was found partly populated. The Ti substitution almost does not change the atomic charges, but induces the essential charge redistribution between d orbitals of Ru that leads to an increase of the eg population. A drastic effect of the Ti impurity on the spin density distribution was revealed; it strongly depends on the electron correlation. In undoped crystals, the MP2 spin density is located only on the Ru and Sr atoms. In the Ti-substituted crystals, the local spin density near an impurity disappears on Sr and localizes on Ru and four O atoms, surrounding it, on orbitals directed along the z axis. The latter are in complete agreement with experiments by Maeno and co-workers [Phys. Rev. B 63, 180504(R) (2001); Phys. Rev. Lett. 88, 197002 (2002)].

Source-reported materials — not catalogue approval

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