Theorie der spontanen Magnetisierung kleiner ferromagnetischer Teilchen

With a modified conception of the Néel sublattices a molecular field theory is developed for small ferromagnetic particles. They are treated as a system of neighboring shells. These are supposed to consist each of atoms with equal average properties and are coupled to the next neighbors by an (exchange-) interaction. To simplify the numerical calculations the model was further modified by taking together all shells of the interior to form a core. Calculations of the temperature dependence of the spontaneous magnetization and of Curie-temperatures have been done for some particle forms and sizes of the f.c.c., b.c.c. and hexagonal lattices. The results are discussed and compared to experimental data of other authors from small particles of nickel, iron and cobalt.