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Confinement and critical regime in doped frustrated quasi-one dimensional magnets

Nicolas Laflorencie·Didier Poilblanc
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Abstract

Ground state and finite temperature properties of a system of coupled frustrated and/or dimerized spin-1/2 chains modeling e.g. the CuGeO$_3$ compound are reviewed. Special emphasis is put on the investigation of the role of impurity doping. A c hain-mean field computation combining exact diagonalisations of the chain hamiltonians together with a mean field treatment of the weak interchain couplings is performed in order to map the microscopic model onto a low-energy effective model. The latter descr ibes a 2-dimensional system of effective spin-1/2 local moments interacting by spacially anisotropic long range spin exchange interactions. An extensive study of this effective model is performed by Stocastic Series Expansion Quantum Monte Carlo for a wide range of temperatures and impurity concentrations. Interesting scaling behaviors of the uniform and staggered spin susceptibilities (above a small ordering Neel temperature due to a residual 3D coupling) can be interpreted in terms of the formation of large clusters of correlated spins carrying a finite magnetization. Such results are reproduced satisfactorily by a new Real Space RG enabling to deal with long range interactions in two-dimensions

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Nicolas Laflorencie, Didier Poilblanc. 2005-02-15. Confinement and critical regime in doped frustrated quasi-one dimensional magnets. https://doi.org/10.1143/jpsjs.74s.277

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