https://doi.org/10.1007/s100530050233
Local environment and electron correlation effects on the magnetic properties of clusters
1
Instituto de Física, Universidad Autónoma de San Luis Potosí,
Alvaro Obregón 64, 78000 San Luis Potosí, Mexico
2
Laboratoire de Physique Quantique (Unité mixte de recherche 5626 du CNRS) ,
Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse, France
Received:
8
January
1998
Revised:
22
June
1998
Accepted:
6
August
1998
Published online: 15 January 1999
The electronic and magnetic properties of clusters are investigated in the framework of the Hubbard model by treating electron correlations effects in a saddle-point slave-boson approximation. The size dependent single-particle spectrum is calculated using a third moment real-space expansion of the local density of states. Results for the magnetic moments, magnetic order, average number of double occupations and hopping renormalizations are given as a function of the local coordination number z, for different representative values of the Coulomb interaction strength U/t and band filling n. Several transitions between paramagnetic, ferromagnetic and antiferromagnetic behaviors are obtained as a function of z. The environment dependence of the magnetic behavior and of the degree of electron delocalization is analyzed. Advantages and limitations of the present approach are discussed.
PACS: 36.40.Cg – Electronic and magnetic properties of clusters / 71.24.+q – Electronic structure of clusters and nanoparticles / 75.10.Lp – Band and itinerant models
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999
