Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 40: Poster Session Correlated Electrons
TT 40.16: Poster
Wednesday, March 13, 2013, 15:00–19:00, Poster D
Strong Spin-Orbital Coupling and Polarization as origin of the Insulating State in Sr2IrO4 — •Markus Aichhorn1, Cyril Martins2, Loig Vaugier2, and Silke Biermann2 — 1Institut für theoretische Physik - Computational Physics, TU Graz, Austria — 2CPHT, Ecole Polytechnique, France
We discuss the notions of spin-orbital polarization and ordering in paramagnetic materials, and address their consequences in transition metal oxides. Extending the combined density functional and dynamical mean field theory (DMFT) scheme to the case of materials with large spin-orbit interactions, we investigate the electronic excitations of the paramagnetic phases of Sr2IrO4 and Sr2RhO4. We show that the interplay of spin-orbit interactions, structural distortions and Coulomb interactions suppresses spin-orbital fluctuations. As a result, the room temperature phase of Sr2IrO4 is a paramagnetic spin-orbitally ordered Mott insulator. In Sr2RhO4, the effective orbital degeneracy is reduced, but the material remains metallic, due to both, smaller spin-orbit and smaller Coulomb interactions. We find excellent agreement of our ab-initio calculations for Sr2RhO4 with angle-resolved photoemission.