Theory of valence mixing for rare-earth compounds |
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Authors: | CET Gonçalves da Silva LM Falicov |
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Institution: | 1. Instituto de Fisica “Gleb Wataghin”, UNICAMP, Campinas 13100 SP, Brazil |
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Abstract: | A theory for the mixed valence state of rare-earth compounds is presented. It includes the following features: (1) two types of electronic states-localized, highly correlated states and itinerant, non-correlated states; (2) a very strong Coulomb repulsion between localized states in the same site; (3) a Coulomb interaction between localized and itinerant states which drives the phase transition; and (4) hybridization between localized and itinerant states which produces the mixed valence state. It is shown that this model produces (a) at T = 0, a variation in the number of localized electrons which may vary in a smooth or in a discontinuous fashion as a function of pressure or alloying; (b) transitions at finite temperature which terminate in a classical critical point. Qualitative agreement with experiment is an encouraging feature of the model. |
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