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Accueil du site > Publications > Publications 2011 > Valence-bond crystal in the extended Kagomé spin-1/2 quantum Heisenberg antiferromagnet : A variational Monte Carlo approach

Valence-bond crystal in the extended Kagomé spin-1/2 quantum Heisenberg antiferromagnet : A variational Monte Carlo approach

Yasir Iqbal, Federico Becca, Didier Poilblanc

par Yasir Iqbal - 7 mars 2011

The highly-frustrated spin-1/2 quantum Heisenberg model with both nearest (J1) and next-nearest (J2) neighbor exchange interactions is revisited by using an extended variational space of projected wave functions that are optimized with state-of-the-art methods. Competition between modulated valence-bond crystals (VBC) proposed in the literature and the Dirac spin liquid (DSL) is investigated. We find that the addition of a \it small ferromagnetic next-nearest-neighbor exchange coupling |J2|>0.09 J1 leads to stabilization of a 36-site unit cell VBC, although the DSL remains a local minimum of the variational parameter landscape. This implies that the VBC is not trivially connected to the DSL : instead it possesses a non-trivial flux pattern and large dimerization.