https://doi.org/10.1007/s100510070023
Ferromagnetism in the periodic Anderson model. A comparison of spectral density approximation (SDA), modified alloy analogy (MAA) and modified perturbation theory (MPT)
LS Festkörpertheorie, Institut für Physik, Humboldt-Universität zu Berlin,
Invalidenstrasse 110, 10115 Berlin, Germany
Corresponding author: a dietrich.meyer@physik.hu-berlin.de
Received:
5
June
2000
Revised:
3
August
2000
Published online: 15 December 2000
We compare different approximation schemes for investigating ferromagnetism in the periodic Anderson model. The use of several approximations allows for a detailed analysis of the implications of the respective methods, and also of the mechanisms driving the ferromagnetic transition. For the Kondo limit, our results confirm a previously proposed mechanism leading to ferromagnetic order, namely an RKKY exchange mediated via the formation of Kondo screening clouds in the conduction band. The contrary case is found in the intermediate-valence regime. Here, the bandshift correction ensuring a correct high-energy expansion of the self-energy is essential. Inclusion of damping effects reduces stability of the ferromagnetic phase.
PACS: 71.10.Fd – Lattice fermion models (Hubbard model, etc.) / 71.28.+d – Narrow-band systems; intermediate-valence solids / 75.30.Mb – Valence fluctuation, Kondo lattice, and heavy-fermion phenomena
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000
