Dresden 2017 – wissenschaftliches Programm
TT 25.4: 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 Takayama3,4, Hidenori Takagi3,4,5, Liu Hao Tjeng1, and Maurits W. Haverkort1,6 — 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 t2g 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.