Magnetization states and magnetization processes in nanostructures: From a single layer to multilayers

The results of combined (experimental, analytical, and micromagnetic simulations) studies on the evolution of magnetization states and processes in ultrathin films and multilayered systems are presented. We show ways to manipulate magnetization distributions in ultrathin magnetic single or multilayers by tuning: the thickness of the magnetic layer, the thickness of either the non-magnetic cap or spacer layer, the magnetic anisotropy, and the geometrical constrictions of the system. In ultrathin magnetic films, both the magnetization distribution and the critical thickness of the magnetization reorientation phase transition (RPT) between perpendicular and in-plane states can be also controlled by post-growth treatments, e.g., by either ion or light irradiation. By changing the geometrical parameters of the nanostructure, as well as by an applied external magnetic field, one can tune magnetic domain sizes in a giant range (of a few orders of magnitude) and induce the RPT. Transitions between two- and three-dimensional magnetization distributions are discussed. The authors present possibilities of the engineering of magnetic properties (e.g. magnetic anisotropy and coercivity field) of nanostructures during deposition processes and post growth treatments, e.g. by ion irradiation and laser annealing. Magnetization distributions in single ultrathin layer and multilayers have been studied both experimentally (using Co films sandwiched between Au, Pt or Mo layers) and theoretically. These huge distribution changes, driven by nanostructure geometry or magnetic field, are shown.