Orbital ordering in frustrated Jahn-Teller systems with 90 degrees exchange

M.V. Mostovoy, D.I Khomskii

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    Abstract

    We show that superexchange interactions in frustrated Jahn-Teller systems with transition metal ions connected by the 90° metal-oxygen-metal bonds (e.g., NaNiO2, LiNiO2, and ZnMn2O4) are much different from those in materials with the 180° bonds. In the 90°-exchange systems spins and orbitals are decoupled: the spin exchange is much weaker than the orbital one and it is ferromagnetic for all orbital states. Though the mean-field orbital ground state is strongly degenerate, quantum orbital fluctuations select particular ferro-orbital states. We explain the orbital and magnetic ordering observed in NaNiO2 and show that LiNiO2 is not a spin-orbital liquid.
    Original languageEnglish
    Article number227203
    Number of pages4
    JournalPhysical Review Letters
    Volume89
    Issue number22
    DOIs
    Publication statusPublished - 2002

    Keywords

    • TRANSITION-METAL OXIDES
    • HEISENBERG-ANTIFERROMAGNET
    • DISORDER
    • LINIO2
    • SPECTRA
    • PHYSICS
    • ORIGIN
    • LIQUID
    • LATIO3

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