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arXiv · 0802.2692

Classical dimers and dimerized superstructure in orbitally degenerate honeycomb antiferromagnet

G. Jackeli·D. I. Khomskii
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Abstract

We discuss the ground state of the spin-orbital model for spin-one ions with partially filled $t_{2g}$ levels on a honeycomb lattice. We find that the orbital degrees of freedom induce a spontaneous dimerization of spins and drive them into nonmagnetic manifold spanned by hard-core dimer (spin-singlet) coverings of the lattice. The cooperative ``dimer Jahn-Teller'' effect is introduced through a magnetoelastic coupling and is shown to lift the orientational degeneracy of dimers leading to a peculiar valence bond crystal pattern. The present theory provides a theoretical explanation of nonmagnetic dimerized superstructure experimentally seen in Li$_2$RuO$_3$ compound at low temperatures.

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G. Jackeli, D. I. Khomskii. 2008-03-18. Classical dimers and dimerized superstructure in orbitally degenerate honeycomb antiferromagnet. https://doi.org/10.1103/physrevlett.100.147203

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