Small Structures: Morphology and Magnetism
Morphology and magnetism are intimately related in epitaxial thin films, but usually in quite a complex manner. Structuring these films into small entities adds on the one hand additional technical difficulties, but on the other hand allows us to study model systems which exhibit simpler or better defined morphological or magnetic properties. Patterning can be done artificially - for instance by lithographical techniques - or by relying on nature - such as by self-organisation.
In this presentation I will show some illustrative examples of such approaches. In particular, ferromagnetic Co/Pt films can be magnetically patterned by an electron beam. It is possible to induce a complete magnetization reorientation from parallel to the film plane into the perpendicular direction. This local magnetic patterning is interesting for possible applications in high density data storage.
The fabrication of small magnetic structures of Co on top of nonmagnetic substrates aims at a better understanding of magnetic domain formation and switching in small technologically relevant elements and extended films. We investigate domain formation for in-plane magnetized structures as a function of their lateral size and thickness. Depending on size, thickness, and magnetic history, single- or multidomain states exist.
Stepped substrates are intrinsically structured templates for growing ferromagnets with changed magnetic properties. In particular, magnetic anisotropy is very sensitively modified by the steps. By controlling these steps, experiments can be performed which give insight into the correlation of morphology, strain, and magnetic properties.