%0 Journal Article
%T A valence bond liquid on the honeycomb lattice
%A Simon A. J. Kimber
%A I. I. Mazin
%A Juan Shen
%A Harald O. Jeschke
%A Sergey V. Streltsov
%A Dimitri N. Argyriou
%A Roser Valenti
%A Daniel I. Khomskii
%J Physics
%D 2013
%I arXiv
%R 10.1103/PhysRevB.89.081408
%X 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.
%U http://arxiv.org/abs/1310.7810v3