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arXiv · 1310.7810

A valence bond liquid on the honeycomb lattice

Simon A. J. Kimber·I. I. Mazin·Juan Shen·Harald O. Jeschke·Sergey V. Streltsov·Dimitri N. Argyriou·Roser Valenti·Daniel I. Khomskii
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Abstract

The honeycomb lattice material Li2RuO3 undergoes a dimerization of Ru4+ cations on cooling below 270C, where the magnetic susceptibility vanishes. We use density functional theory calculations to show that this reflects the formation of a 'valence bond crystal', with a strong bond disproportionation. On warming, x-ray diffraction shows that discrete three-fold symmetry is regained on average, and the dimerization apparently disappears. In contrast, local structural measurements using high-energy x-rays, show that disordered dimers survive at the nanoscale up to at least 650C. The high temperature phase of Li2RuO3 is thus an example of a valence bond liquid, where thermal fluctuations drive resonance between different dimer coverages, a classic analogue of the resonating valence bond state often discussed in connection with high T$_c$ cuprates.

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Simon A. J. Kimber, I. I. Mazin, Juan Shen, Harald O. Jeschke, Sergey V. Streltsov, Dimitri N. Argyriou, Roser Valenti, Daniel I. Khomskii. 2013-10-29. A valence bond liquid on the honeycomb lattice. https://doi.org/10.1103/physrevb.89.081408

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