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MA: Fachverband Magnetismus

MA 21: Correlated Electrons: Frustrated Magnets - Strong Spin-Orbit Coupling 1

MA 21.4: Vortrag

Dienstag, 21. März 2017, 10:15–10:30, HSZ 304

Long-range interactions in the effective low energy Hamiltonian of Sr₂IrO₄: a core level resonant inelastic x-ray scattering — •Stefano Agrestini¹, Chang-Yang Kuo¹, Marco Moretti Sala², Zhiwei Hu¹, Deepa Kasinathan¹, Pieter Glatzel², Tomohiro Takayama^3,4, Hidenori Takagi^3,4,5, Liu Hao Tjeng¹, and Maurits W. Haverkort^1,6 — ¹Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — ²ESRF, Grenoble, France — ³Department of Physics and Department of Advanced Materials, University of Tokyo, Japan — ⁴Max Planck Institute for Solid State Research, Stuttgart, Germany — ⁵Institute for Functional Matter and Quantum Technologies, University of Stuttgart, Germany — ⁶Institute for theoretical physics, Heidelberg University, Germany

The iridates have received tremendous attention due to the high expectations of finding new exotic phenomena and the long-sought materialization of the Kitaev model. Experimentally, however, most compounds order magnetically. Here we address the puzzle of the ground state in iridates by measuring core-to-core resonant inelastic x-ray spectroscopy on Sr₂IrO₄. From the spectra analysis we found that Sr₂IrO₄ is highly covalent with the effective t_2g orbitals very extended spatially. They are not the standard orbitals with nearest-neighbor-only magnetic interactions that most people have in mind. We thus explain why compass models are not realized in most studied iridates and we show a pathway how one can achieve the Kitaev model using other crystal structures or transition metal ions.