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Article Dans Une Revue Physical Review B: Condensed Matter and Materials Physics (1998-2015) Année : 2011

Competing Valence Bond Crystals in the Kagome Quantum Dimer Model

Résumé

The singlet dynamics which plays a major role in the physics of the spin-1/2 Quantum Heisenberg Antiferromagnet (QHAF) on the Kagome lattice can be approximately described by projecting onto the nearest-neighbor valence bond (NNVB) singlet subspace. We re-visit here the effective Quantum Dimer Model which originates from the latter NNVB-projected Heisenberg model via a non-perturbative Rokhsar-Kivelson-like scheme. By using Lanczos exact diagonalisation on a 108-site cluster supplemented by a careful symmetry analysis, it is shown that a previously-found 36-site Valence Bond Crystal (VBC) in fact competes with a new type of 12-site "{\it resonating-columnar}" VBC. The exceptionally large degeneracy of the GS multiplets (144 on our 108-site cluster) might reflect the proximity of the Z_2 dimer liquid. Interestingly, these two VBC "emerge" in {\it different topological sectors}. Implications for the interpretation of numerical results on the QHAF are outlined.

Dates et versions

hal-00637194 , version 1 (31-10-2011)

Identifiants

Citer

Didier Poilblanc, Grégoire Misguich. Competing Valence Bond Crystals in the Kagome Quantum Dimer Model. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2011, 84 (21), pp.214401. ⟨10.1103/PhysRevB.84.214401⟩. ⟨hal-00637194⟩
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