As a result of quantum-mechanical calculations, certain elements like Fe, Ni, Co and Gd and some compounds show a spontaneous magnetization below the so-called Curie temperature. The magnetization value is a material constant and does not depend on the applied magnetic field H. In contrast to this theory, magnetization measurements of ferromagnetic solids show a typical dependency on the magnetic field. An explanation for this difference lies in the integration of the whole sample during these measurements. In reality, the sample is divided in many isolated regions with a constant magnetization value (Weiss regions), and the magnetization vector is changing from one region to another. The total magnetization can be calculated bei integration over all regions. In this experiment we study the case of sample comparable to structural elements like domain width or domain wall width.

Instruction (allemand)