SKM 2023 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 21: Correlated Electrons: Electronic Structure Calculations
TT 21.6: Vortrag
Dienstag, 28. März 2023, 10:45–11:00, HSZ 201
LaVO3: A true Kugel-Khomskii system — •Xuejing Zhang1, Erik Koch1,2, and Eva Pavarini1,2 — 1Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany — 2JARA High-Performance Computing, 52062 Aachen, Germany
Almost 50 years ago, Kugel’ and Khomskii (KK) showed in a classic paper that, in strongly correlated materials, orbital ordering can arise from pure superexchange interactions [1]. It can, however, also result from the crystal-field splitting via a lattice distortion, i.e., from electron-lattice coupling. Despite the intensive search, it has been hard to find an undisputed realization of a KK system. We identify that the t2g2 perovskite LaVO3, in its orthorhombic phase, is a rare case of a system hosting an orbital-ordering KK phase transition rather than being controlled by the Coulomb-enhanced crystal-field splitting [2]. We find that, as a consequence of this, the magnetic transition is close to (and even above) the superexchange driven orbital-ordering transition, whereas typically magnetism arises at much lower temperatures than orbital ordering. To explore the effects of crystal-field splitting and filling, we compare to YVO3 and t2g1 titanates. In all these materials the crystal field is sufficiently large to suppress the KK phase transition [3].
[1] K. I. Kugel’ and D. I. Khomskii, Zh. Eksp. Teor. Fiz. 64, 1429 (1973) [Sov. Phys. JETP 37, 725 (1973)]
[2] X. J. Zhang, E. Koch, E. Pavarini, Phys. Rev. B 106, 115110 (2022)
[3] X. J. Zhang, E. Koch, E. Pavarini, Phys. Rev. B 102, 035113 (2020)