MAGNETIZATION PROCESSES IN HIGH ANISOTROPY SYSTEMS

In high anisotropy systems the magnetocrystalline anisotropy energy can be comparable to the exchange energy. The thickness of domain walls can be as small as the interatomic distance (narrow domain walls). This leads to intrinsic pinning of domain walls, the discreteness of the matter playing, as this is the case for point defects, the role of very efficient pinning centers (magnetic Peirls potential, analogous to the one which prevents the motion of dislocations). The concept of intrinsic pinning has been recently discovered in high-T-c materials where the order parameter has a sinusoidal-like variation along the c-axis. Among other results: 1/H law characterizing the dynamics of disordered alloys, effective anisotropy energy of field-induced non-colinear magnetic structures in ferrimagnetic intermetallics, quantitative understanding of the macroscopic magnetism of amorphous rare-earth based alloys, etcetera.