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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. |
