Valence transition in the periodic Anderson model
A very rich phase diagram has recently been found in CeCu<Subscript>2</Subscript>Si<Subscript>2</Subscript> from high pressure experiments where, in particular, a transition between an intermediate valence configuration and an integral valent heavy fermion state has been observed. We show that such a valence transition can be understood in the framework of the periodic Anderson model. In particular, our results show a breakdown of a mixed-valence state which is accompanied by a drastic change in the f occupation in agreement with experiment. This valence transition can possibly be interpreted as a collapse of the large Fermi surface of the heavy fermion state which incorporates not only the conduction electrons but also the localized f electrons. The theoretical approach used in this paper is based on the novel projector-based renormalization method (PRM). With respect to the periodic Anderson model, the method was before only employed in combination with the basic approximations of the well-known slave-boson mean-field theory. In this paper, the PRM treatment is performed in a more sophisticated manner where both mixed as well as integral valent solutions have been obtained. Furthermore, we argue that the presented PRM approach might be a promising starting point to study the competing interactions in CeCu<Subscript>2</Subscript>Si<Subscript>2</Subscript> and related compounds. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006
Year of publication: |
2006
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Authors: | Hübsch, A. ; Becker, K. W. |
Published in: |
The European Physical Journal B - Condensed Matter and Complex Systems. - Springer. - Vol. 52.2006, 3, p. 345-353
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Publisher: |
Springer |
Subject: | 71.10.Fd Lattice fermion models (Hubbard model | etc.) | 71.27.+a Strongly correlated electron systems | heavy fermions | 75.30.Mb Valence fluctuation | Kondo lattice | and heavy-fermion phenomena |
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