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Accueil du site > Publications > Publications 2009 > Theory of the field-induced BEC in the frustrated spin-1/2 dimer compound BaCuSi2O6

Theory of the field-induced BEC in the frustrated spin-1/2 dimer compound BaCuSi2O6

N. Laflorencie and F. Mila

par Nicolas Laflorencie - 28 novembre 2008

arxiv:0811.4745v1, to appear in Phys. Rev. Lett. (2009)

Building on recent neutron and NMR experiments, we investigate the field-induced exotic criticality observed in the frustrated spin-1/2 dimer compound BaCuSi2O6 using a frustrated model with two types of bilayers. A semiclassical treatment of the effective hard-core boson model shows that perfect inter-layer frustration leads to a 2D-like critical exponent phi=1 without logarithmic corrections and to a 3D low temperature phase with different but non vanishing triplet populations in both types of bilayers. These results further suggest a simple phenomenology in terms of a field-dependent transverse coupling in the context of which we reproduce the entire field-temperature phase diagram with Quantum Monte Carlo simulations.