Dresden 2020 – wissenschaftliches Programm
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TT 3.2: Vortrag
Montag, 16. März 2020, 09:45–10:00, HSZ 201
Melting of excitonic dispersion in LaCoO3: theory and experiment — Atsushi Hariki1, Ru-Pan Wang2, Andrii Sotnikov1,3, Keisuke Tomiyasu4, Davide Betto5, Nicholas B. Brookes5, Yohei Uemura2, Mahnaz Ghiasi2, Frank M. F. de Groot2, and •Jan Kuneš1,6 — 1Institute of Solid State Physics, TU Wien — 2Debye Institute for Nanomaterials Science, Utrecht University — 3Akhiezer Institute for Theoretical Physic, Kharkiv — 4Department of Physics, Tohoku University — 5European Synchrotron Radiation Facility, Grenoble — 6Institute of Physics, Czech Academy of Sciences
We present Co L3-edge resonant inelastic x-ray scattering (RIXS) on bulk LaCoO3 across the thermally-induced spin-state crossover around 100 K. Owing to a high energy resolution of 20 meV, we observe unambiguously the dispersion of the intermediate-spin (IS) excitations in the low temperature regime. Approaching the intermediate temperature regime, the IS excitations are damped and the bandwidth reduced. The observed behavior can be well described by a model of mobile IS excitons with strong attractive interaction, which we solve using dynamical mean-field theory for hard-core bosons. Our results provide a detailed mechanism of how HS and IS excitations interact to establish the physical properties of cobaltite perovskites.