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O: Fachverband Oberflächenphysik

O 39: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles III (jointly with TT)

O 39.2: Talk

Wednesday, March 28, 2012, 10:45–11:00, HE 101

Ab initio determination of excitation energies and magnetic couplings in correlated, quasi two-dimensional iridates — •Vamshi Katukuri¹, Hermann Stoll², Jeroen van den Brink¹, and Liviu Hozoi¹ — ¹Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany — ²Institute for Theoretical Chemistry, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany

Using many-body quantum-chemical techniques, we compare the electronic structure of two layered j=1/2 Ir 5d⁵ oxides, Sr₂IrO₄ and Ba₂IrO₄. Multi-orbital and multiplet physics, spin-orbit interactions and O 2p to Ir 5d charge-transfer effects are all treated on equal footing, fully ab initio. Our calculations provide valuable complementary information to hybrid schemes based on density-functional theory and dynamical mean-field theory. In particular, for Sr₂IrO₄, the computed magnetic constant (J), d-d and charge-transfer excitation energies show good agreement with recent resonant inelastic x-ray scattering and optical measurements. For Ba₂IrO₄, we find a J that is even somewhat larger, which renders it roughly a factor 2-3 lower than the J’s in typical quasi 2D cuprates. This might in itself be encouraging for a scenario of magnetic mediated super-conductivity in doped iridates.