NOVEL MAGNETIZATION PROCESSES IN FERRIMAGNETIC MULTILAYERS WITH RANDOM ANISOTROPY

We carried out a numerical study of magnetization processes in ferrima gnetic multilayers in the presence of pinning forces acting on one of the magnetic components. The multilayers consist of an alternation of two ferromagnetic materials (M and T) which are assumed antiferromagne tically coupled through the interfaces (as in Fe/Tb multilayers for in stance). A random anisotropy field acts on the magnetization of materi al T. The reversal of the magnetization of the multilayers when the ap plied field is swept from positive saturation to negative saturation i s characterized by a competition between coherent rotation and nucleat ion-propagation mechanisms. In this competition the rotational hystere sis induced by the random anisotropy on the magnetization of material T plays a crucial role. Very original features have been observed in t he magnetization processes of these systems such as crossed hysteresis loops with a negative remanent magnetization. An overview of these ma gnetization processes below and above the compensation temperature is given in this paper.