Magnetization Studies of CeCu2Si2−xGex Alloys

Abstract

The heavy fermion systems have attracted the attention of the theorists as well as the experimentalists recently[1]. In particular CeCu2Si2 has been studied extensively. This system has been viewed as a nearly trivalent Kondo lattice. The large electronic specific heat coefficient has been attributed by some authors as resulting from a large density of quasiparticle states near the Fermi level. The superconducting transition temperature Tc and the critical fields of the heavy fermion systems have been related to the Kondo temperature by Tachiki and Maekawa recently[2]. There is evidence that the periodicity of the Ce lattice is essential for the heavy fermion state of CeCu2Si2[3]. In an effort to investigate the evolution of the heavy fermion state as a function of the strength of the Kondo interaction, we have undertaken a study of the pseudoternary series CeCu2Si2−xGex. In this paper we report some preliminary results of the normal state magnetic properties. Two characteristics of this system are (i) the periodicity of the Ce lattice is preserved; (ii) Ge contributes the same number of electrons as Si to the conduction band. Therefore the changes in the electronic structure are expected to be gradual. Also, the Ge rich end member, namely CeCu2Ge2, is also known to be a Kondo lattice that orders antiferromagnetically at 4.1K.