SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 30: Complex Oxides

TT 30.4: Vortrag

Mittwoch, 29. März 2023, 10:15–10:30, HSZ 204

Orbital imaging of the spin state transition in LaCoO₃ — Brett Leedahl¹, Daisuke Takegami¹, Martin Sunderamnn^1,2, Hlynur Gretarsson^1,2, Alexander Komarek¹, Arata Tanaka³, Maurits Haverkort⁴, and •Liu Hao Tjeng¹ — ¹MPI-CPfS, Dresden, Germany — ²DESY/PETRA-III, Hamburg, Germany — ³Department of Quantum Matter, Hiroshima University, Japan — ⁴Institute for Theoretical Physics, Heidelberg University, Germany

Here we have investigated the Co 3d orbital occupation in LaCoO₃ across the spin state transition using the recently developed x-ray-based orbital-imaging method. The images collected allow for a direct determination of the amount of the Co t_2g and e_g holes. We find that, at the lowest temperatures, the low-spin state with the nominally t_2g⁶e_g⁰ electron configuration does have holes in the t_2g subshell which we attribute to the presence of spin-orbit interaction. The hole amount, however, sets limits to the minimum energy gap between the lattice-frozen low-spin and high-spin states. At high temperatures, we find that the high-spin state occupation is about half (!) of the value reported in the most recent literature. Implications for the ab-initio modeling of the spin-state transition process are discussed.