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Título:
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Variational mean-field approach to the double-exchange model
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Autores:
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Alonso, J. L. ;
Fernández Pérez, Luis Antonio ;
Guinea, F. ;
Laliena, V. ;
Martín Mayor, Víctor
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Tipo de documento:
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texto impreso
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Editorial:
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American Physical Society, 2011-02-01
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Dimensiones:
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application/pdf
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Nota general:
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info:eu-repo/semantics/openAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias: Física
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Materia = Ciencias: Física: Física-Modelos matemáticos
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Tipo = Artículo
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Resumen:
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It has been recently shown that the double exchange Hamiltonian, with weak antiferromagnetic interactions, has a richer variety of first- and second-order transitions than previously anticipated, and that such transitions are consistent with the magnetic properties of manganites. Here we present a thorough discussion of the variational mean-field approach that leads to these results. We also show that the effect of the Berry phase turns out to be crucial to produce first-order paramagnetic-ferromagnetic transitions near half filling with transition temperatures compatible with the experimental situation. The computation relies on two crucial facts: the use of a mean-field ansatz that retains the complexity of a system of electrons with off-diagonal disorder, not fully taken into account by the mean-field techniques, and the small but significant antiferromagnetic superexchange interaction between the localized spins.
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En línea:
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https://eprints.ucm.es/40116/1/Fern%C3%A1ndezP%C3%A9rezLuisAntonio39LIBRE.pdf
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