ABSTRACT
The electronic structure and magnetic properties of Mn1-xCrxSb alloys were investigated for the full concentration range. The stability of the concentration-dependent magnetic structure of the alloys were analysed on the basis of spin-spiral calculations as well as using the Monte Carlo (MC) simulations based on the Heisenberg model with the exchange coupling parameters calculated from first-principles. A leading contribution to the canted magnetic structure in Mn1-xCrxSb is the competition of the direct Cr-Cr and Mn-Mn exchange interactions having opposite signs. Furthermore, a strong impact of long-distance RKKY-type interactions is demonstrated. MC simulations at finite temperature were used to obtain the magnetic phase diagram for Mn1-xCrxSb alloys, which is in reasonable agreement with the experimental data.
ABSTRACT
The electronic structure and magnetic properties of Cr-Sb compounds with zinc-blende and wurtzite structure have been studied by means of the Korringa-Kohn-Rostoker (KKR) band structure method. The occurrence of a half-metallic behavior has been investigated for the bulk systems as a function of lattice parameter, as well as for thin films deposited on different substrates. In the latter case the influence of the surface and interface on the electronic structure is discussed in addition. To study magnetic order in the bulk and within the films, exchange coupling parameters have been calculated from first principles. They have been used for subsequent Monte Carlo simulations, based on a classical Heisenberg Hamiltonian, to obtain the Curie temperature.
ABSTRACT
The structural and magnetic properties of CrSb compounds with NiAs structure have been studied by means of the Korringa-Kohn-Rostoker (KKR) band structure method. An analysis of the structural and magnetic stability has been performed on the basis of total energy calculations for various magnetic states. The magnetic properties at finite temperature have been investigated by means of Monte Carlo simulations on the basis of a classical Heisenberg Hamiltonian and the exchange coupling parameters calculated from first principles. This approach allowed us to determine the critical temperature in good agreement with experiment.
ABSTRACT
Within the extension of new services for mentally ill and disabled peoples outside of inpatient settings, the Landschaftsverband Rheinland (LVR) decided in 1990 to finance day care facilities especially for those patients who could previously not be integrated in the existing community psychiatry service structure due to the severity of their illness or handicap. A cost reducing effect in the clinical and residential service area was also intended. The first ten of these facilities were included in a 2-year research project. This report includes findings in various sectors: characteristics of the user group, functions and focal points of care, association with other community psychiatry services, cost effectiveness, and user opinions. Most visitors experienced a stabilisation of their personal situation and improvement of their quality of life. The average length of hospital stays was reduced from 102 to 25 days per year. The hopes accompanied with the programme were only partially fulfilled; possible consequences are discussed.
