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Ferromagnetic Kondo‐lattice model: Application to thin ferromagnetic and semiconducting local moment films
Author(s) -
Nolting W.,
Santos C.
Publication year - 2003
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200301666
Subject(s) - condensed matter physics , magnon , ferromagnetism , quasiparticle , magnetic moment , curie temperature , magnetization , physics , electron , materials science , superconductivity , quantum mechanics , magnetic field
We present a many‐body approach to the electronic and magnetic properties of the Kondo‐lattice model. This model is considered a candidate for the description of magnetic materials the characteristic properties of which are mainly determined by an exchange coupling of itinerant electrons to a system of localized magnetic moments. This coupling leads to a distinct temperature‐dependence of the electronic quasiparticle spectrum and to magnetic properties, as e.g. the Curie temperature T C or magnon dispersions, which are strongly influenced by the band electron selfenergy. The model studies are applied to thin ferromagnetic EuO(100) films. For a realistic description we present a multiband extension of the Kondo‐lattice model with a single‐electron part taken from a tight‐binding‐LMTO bandstructure calculation. The proposed method avoids the double counting of relevant interactions and takes into account the correct symmetry of atomic orbitals. The layer‐dependent magnetization as well as quasiparticle density of states are discussed as functions of the film thickness. For a 20‐layer film the existence of a surface state is predicted, which may lead to a temperature‐driven surface halfmetal‐insulator transition.