The high temperature expansion of the classical XYZ chain |
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Authors: | EV Corrêa Silva Onofre Rojas James EF Skea SM de Souza MT Thomaz |
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Institution: | 1. Departamento de Matemática e Computação, Faculdade de Tecnologia, Universidade do Estado do Rio de Janeiro, Estrada Resende-Riachuelo, s/no, Morada da Colina, CEP 27523-000, Resende-RJ, Brazil;2. Departamento de Ciências Exatas, Universidade Federal de Lavras, Caixa Postal 3037, CEP 37200-000, Lavras-MG, Brazil;3. Instituto de Física, Universidade do Estado do Rio de Janeiro, R. São Francisco Xavier no 524, Bloco B, CEP- 20559-900, Rio de Janeiro-RJ, Brazil;4. Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/no, CEP 24210-346, Niterói-RJ, Brazil |
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Abstract: | The β-expansion of the Helmholtz free energy (HFE) up to order β12 of the classical XYZ model with a single-ion anisotropy term and external magnetic field is calculated and compared to the numerical solution of Joyce's Phys. Rev. Lett. 19 (1967) 581] for the XXZ classical model, with neither single-ion anisotropy term nor external magnetic field. This comparison shows that the derived analytical expansion is valid for intermediate temperatures such as kT/Jx≈0.5. The specific heat and magnetic susceptibility of the S=2 antiferromagnetic chain can be approximated by their respective classical results, within an error of 2.5%, up to kT/J≈0.8. For a vanishing external magnetic field the ferromagnetic and antiferromagnetic chains are shown to have the same classical HFE; their behaviour in a non-vanishing external magnetic field is also described. |
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Keywords: | Strongly correlated electrons High temperature expansion Classical XYZ chain model |
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