Application of light ion irradiation on the magnetic properties of exchange bias layers

Due to the reduced dimension, the magnetic properties of ultrathin magnetic films and multilayers, e.g. magnetic anisotropies and exchange coupling, often depend strongly on the surface and interface structure. In addition chemical composition, crystallinity, grain sizes and their distribution govern the magnetic behaviour. All these structural properties can be modified by light-ion irradiation in an energy range from 5 – 150 keV due to the energy loss of the ions in the solid along their trajectory. Consequently the magnetic properties can be tailored by ion irradiation. Similar effects can also be observed using Ga+ ion irradiation, which is the common ion source in focused ion beam lithography. Examples for ion induced modifications of magnetic properties in exchange bias systems are presented.

Due to the local nature of the interaction, magnetic patterning without affecting the surface topography becomes feasible, which may have an applied interest. In contrast to topographic nanostructures the surrounding area of these nanostructures can be left ferromagnetic leading to new phenomena at their mutual interface.

Most of the material systems discussed here are important for technological applications. It will be shown that light-ion irradiation has many advantages for design of new material properties and the fabrication technology of actual devices.