SKM 2023 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 10: Correlated Electrons: Other Materials
TT 10.12: Talk
Monday, March 27, 2023, 18:00–18:15, HSZ 204
Spin-orbit entangled crystal-field excitations in 5d4 j=0 osmates — •Philipp Warzanowski1, Marco Magnaterra1, Philipp Stein1, Quentin Faure2, Christoph Sahle2, Holger Schwab1, Thomas Lorenz1, Petra Becker3, Ladislav Bohatý3, Paul H. M. van Loosdrecht1, and Markus Grüninger1 — 1Institute of Physics II, University of Cologne — 2European Synchrotron Radiation Facility, Grenoble Cedex, France — 3Sect. Crystallography, Institute of Geology and Mineralogy, University of Cologne
For strong spin-orbit coupling, the d4 electron configuration may show a non-magnetic j=0 ground state. In 5d4 iridates, magnetic behavior has been discussed controversially and finally it has been attributed to defects, while excitonic magnetism has been proposed for 4d4 ruthenates. We show that the j=0 state is very well realized in the cubic antifluorite-type 5d4 osmates K2OsCl6 and K2OsBr6. The magnetic susceptibility exhibits van-Vleck type magnetism without a sizeable Curie-Weiss contribution. Employing resonant inelastic x-ray scattering (RIXS) and infrared spectroscopy as complementary techniques, we investigate the electronic excitations and determine the electronic parameters by comparison with local multiplet calculations. The cubic crystal-field splitting 10 Dq and the charge transfer energy are 15% smaller for the chlorine compound than for its bromide sister, whereas the intra-t2g excitation energies are reduced by 4%. This allows us to quantify the influence of the eg orbitals on the effective spin-orbit coupling for the t2g orbitals.