Eur. Phys. J. B 52, 345-353 (2006)
https://doi.org/10.1140/epjb/e2006-00303-x

Valence transition in the periodic Anderson model

¹ Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Straße 38, 01187 Dresden, Germany
² Department of Physics, University of California, Davis, CA, 95616, USA
³ Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany

Corresponding author: ^a huebsch@pks.mpg.de

Received: 14 November 2005
Revised: 12 July 2006
Published online: 1 August 2006

Abstract

A very rich phase diagram has recently been found in CeCu₂Si₂ 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 CeCu₂Si₂ and related compounds.