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arXiv · 1002.0178

Ring-exchange interaction in doubly degenerate orbital system

Joji Nasu·Sumio Ishihara
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Abstract

Ring-exchange (RE) interaction in Mott insulator with doubly degenerate $e_g$ orbitals is studied. Hamiltonian for the RE interaction is derived by the perturbational calculation. A remarkably weak RE interaction destroys the orbital order caused by the order-by-fluctuation mechanism in the nearest-neighbor exchange-interaction model. A long range order of magnetic octupole moment, i.e. complex orbital wave functions, appears. Competition between octupole and quadrupole interactions strongly suppresses ordered moments.

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Joji Nasu, Sumio Ishihara. 2010-02-01. Ring-exchange interaction in doubly degenerate orbital system. https://doi.org/10.1143/jpsj.80.033704

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