INTERACTIVE AND COOPERATIVE MAGNETIZATION PROCESSES IN HARD MAGNETIC-MATERIALS

Magnetization processes in rare earth - transition metal intermetallic compounds in general have to be investigated within the framework of three different scales: (1) The atomistic level taking into account the intrinsic magnetic properties of rare earth and transition metal ions. (2) The nanomagnetic level taking into account perturbations of exchange interactions and of the magnetic anisotropies in individual grains. (3) The micromagnetic level taking into account short range exchange interactions as well as long range dipolar interactions in ensembles of grains. It is shown that a universal relation may be derived for the coercive field of permanent magnets as produced by sintering, melt-spinning or mechanical alloying.