Knaflic T, Jeglic P, Komelj M, Zorko A, Biswas PK, Ponomaryov AN, Zvyagin SA, Reehuis M, Hoser A, Geiss M, Janek J, Adler P, Felser C, Jansen M, Arcon D (2020)
Publication Type: Journal article
Publication year: 2020
Book Volume: 101
Article Number: 024419
Journal Issue: 2
DOI: 10.1103/PhysRevB.101.024419
Recently, a Verwey-type transition in the mixed-valence alkali sesquioxide Cs4O6 was deduced from the charge ordering of molecular peroxide O22- and superoxide O2- anions accompanied by the structural transformation and a dramatic change in electronic conductivity [Adler, Sci. Adv. 4, eaap7581 (2018)2375-254810.1126/sciadv.aap7581]. Here, we report that in the sister compound Rb4O6, a similar Verwey-type charge ordering transition is strongly linked to O2- orbital and spin dynamics. On cooling, a powder neutron diffraction experiment reveals a charge ordering and a cubic-to-tetragonal transition at TCO=290 K, which is followed by a further structural instability at Ts=92 K that involves an additional reorientation of magnetic O2- anions. Magnetic resonance techniques supported by density functional theory computations suggest the emergence of a peculiar type of π∗-orbital ordering of the magnetically active O2- units, which promotes the formation of a quantum spin state composed of weakly coupled spin dimers. These results reveal that as in 3d transition-metal compounds, also in the π∗ open-shell alkali sesquioxides the interplay between Jahn-Teller-like electron-lattice coupling and Kugel-Khomskii-type superexchange determines the nature of orbital ordering and the magnetic ground state.
APA:
Knaflic, T., Jeglic, P., Komelj, M., Zorko, A., Biswas, P.K., Ponomaryov, A.N.,... Arcon, D. (2020). Spin-dimer ground state driven by consecutive charge and orbital ordering transitions in the anionic mixed-valence compound Rb4 O6. Physical Review B, 101(2). https://doi.org/10.1103/PhysRevB.101.024419
MLA:
Knaflic, T., et al. "Spin-dimer ground state driven by consecutive charge and orbital ordering transitions in the anionic mixed-valence compound Rb4 O6." Physical Review B 101.2 (2020).
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