Dingle temperatures and Fermi surface changes in dilute substitutional Cu alloys. I. Charge transfer effects

Abstract

De Haas-van Alphen (DHVA) quantities have been calculated for several impurities (Al, Si, P, Zn, Ge) in dilute copper alloys and compared with experiment. The theory used describes the scattering of Bloch electrons by a cluster consisting of an impurity together with one or more neighbouring shells of host atoms. Two types of potential, either constructed in a standard way or calculated self-consistently, are used and their representation of the electronic structure of both host and alloys is investigated extensively. In particular, the effect of charge transfer is studied. Comparison of measured and calculated Dingle temperatures xi and cross-sectional area changes delta Ai reveals that these quantities depend on charge transfer in a different way. While charge transfer influences only the neck values of x appreciably, it enhances the delta Ai values considerably and nearly uniformly. The non-selfconsistent potentials reproduce the Cu(Si)and Cu(Al) DHVA properties quite well but yield less good results for the other alloys, clearly because the dynamical screening effects are not accounted for. The self-consistent potential for Cu(P) is good. The results for the other alloys suggest that it is worth while obtaining these potentials for the (at least 13-atomic) impurity cluster as a whole, rather than for the impurity only.