Self-energy approach to the correlated Kondo-lattice model

Abstract

We develop an interpolating self-energy approach to the correlated Kondo-lattice model. The correlation of the band electrons is taken into account by a Hubbard interaction. The method is based on a self-energy ansatz, the structure of which allows to fulfill a maximum number of exactly solvable limiting cases. The parameters of the ansatz are fitted to spectral moments via high-energy expansion of the self-energy. The band electron correlations are taken into account by an effective medium approach being correct in the strong coupling (U) regime. The theory is considered reliable for all temperatures, band occupations, and exchange couplings. Results are presented for the respective dependencies of spectral densities, quasiparticle densities of states, and characteristic correlation functions, and interpreted in terms of elementary spin exchange processes between itinerant conduction electrons and localized magnetic moments. The appearance of magnetic polarons, the typical quasiparticle of Kondo-lattices, in the energy spectrum is worked out. Spin exchange processes prevent a total spin polarization of the band electrons even for arbitrarily strong exchange couplings as long as the local moments are represented by quantum mechanical spins.

arXiv comment9 pages, 5 figures, to be published in Phys. Rev. B

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• Magnetic phases in the correlated Kondo-lattice model
• Ferromagnetic polarons in the one-dimensional ferromagnetic Kondo model with quantum mechanical S=3/2 core spins
• Carrier induced ferromagnetism in concentrated and diluted local-moment systems
• Ferromagnetic EuS films: Magnetic stability, electronic structure and magnetic surface states
• Magnetic Phase Diagrams of Manganites-like Local-Moment Systems with Jahn-Teller distortions
• Ferromagnetic Kondo-Lattice Model
• Interacting spin waves in the ferromagnetic Kondo lattice model
• Proper weak-coupling approach to the periodic s-d(f) exchange model
• Ferromagnetism in multi-band Kondo lattice model
• Scaling Between Periodic Anderson and Kondo Lattice Models
• Periodic Anderson model with Holstein phonons for the description of the Cerium volume collapse
• Two-band ferromagnetic Kondo-lattice model for local-moment half-metals
• Band model for the understanding of ferromagnetism in semiconductors and insulators