Kulyk M. The role of anisotropy in the processes of magnetization reversal of magnetic nanostructures and nanocomposites.

The effect of anisotropy, percolation and exchange interaction on magnetization of nanostructures is investigated in this work. The objects under investigation: Co/Al2O3 nanogranular composites, thin ferromagnetic films of Heusler alloy. It is shown that the presence of a superferromagnetic state in nanogranular composites with perpendicular anisotropy changes the value of the transition field from a homogeneous to an inhomogeneous state. It is also shown that it modifies by additional plane anisotropy. It has been shown that exceeding the percolation threshold leads to a two-phase state of the composite, where there is a contribution from the granular part and the percolated part of the granules. It is shown that in the films of the Heusler alloy there may be anisotropy, capable to reorientation, induced by a magnetic field. The simulation of the magnetization reversal of the ensemble of interacting superparamagnetic moments showed that they can be reversed due to the complete loss of stability of the moment of the entire ensemble, and not only the Neelian relaxation and the loss of the stability of the super-ferromagnetic phase.