W. Nolting

Theory of field-induced spin reorientation transition in thin Heisenberg films

We consider the spin reorientation transition in a ferromagnetic Heisenberg monolayer with a second-order single-ion anisotropy as a function of temperature and external field. Up to now analytical methods give satisfying results only for the special case that the external field is aligned parallel to the easy axis of the crystal. We propose a theory based on a generalization of the Callen decoupling, which can be used for an arbritrary direction of the external field. Excellent agreement between our results and quantum Monte Carlo data is found for the field-induced reorientation at finite temperatures. Additionally, we discuss the temperature dependence of the transition in detail.

Temperature-dependent quasiparticle band structure of the ferromagnetic semiconductor EuS

We present calculations for the temperature-dependent electronic structure of the ferromagnetic semiconductor EuS. A combination of a many-body evaluation of a multiband Kondo-lattice model and a first-principles

Ferromagnetism in the Kondo-lattice model

T=0

On the Temperature-Dependent Exchange Splitting in the Quasiparticle Bandstructure of Ni

\char21{}band-structure calculation [tight-binding linear muffin-tin orbital (TB-LMTO)] is used to get realistic information about temperature- and correlation effects in the EuS energy spectrum. The combined method strictly avoids double-counting of any relevant interaction. Results for EuS are presented in terms of spectral densities, quasiparticle band structures, and quasiparticle densities of states, and that over the entire temperature range.

Dynamical mean-field study of ferromagnetism in the periodic Anderson model

We propose a modified Rudermann, Kittel, Kasuya, Yosida (RKKY) technique to evaluate the magnetic properties of the ferromagnetic Kondo-lattice model. Together with a previously developed self-energy approach to the conduction-electron part of the model, we obtain a closed system of equations which can be solved self-consistently. The results allow us to study the conditions for ferromagnetism with respect to the band occupation n, the interband exchange coupling J, and the temperature T. Ferromagnetism appears for relatively low electron (hole) densities, while it is excluded around half-filling

TEMPERATURE-DEPENDENT BAND STRUCTURE OF A FERROMAGNETIC SEMICONDUCTOR FILM

(n=1).

Magnetic properties of disordered Heisenberg binary spin system with long-range exchange

For small J the conventional RKKY theory

Origin of the temperature dependence of interlayer exchange coupling in metallic trilayers

(\ensuremath{\sim}{J}^{2})

Kondo lattice model: Application to the temperature-dependent electronic structure of EuO(100) films

is reproduced, but with strong deviations for very moderate exchange couplings. For not-too-small n a critical

Magnetic Properties of Thin Ferromagnetic Semiconducting Films

{J}_{c}