Improving the magnetic properties of Co-CoO systems by designed oxygen implantation profiles.

Oxygen implantation in ferromagnetic Co thin films is shown to be an advantageous route to improving the magnetic properties of Co-CoO systems by forming multiple nanoscaled ferromagnetic/antiferromagnetic interfaces homogeneously distributed throughout the layer. By properly designing the implantation conditions (energy and fluence) and the structure of the films (capping, buffer, and Co layer thickness), relatively uniform O profiles across the Co layer can be achieved using a single-energy ion implantation approach. This optimized configuration results in enhanced exchange bias loop shifts, improved loop homogeneity, increased blocking temperature, reduced relative training effects and increased retained remanence in the trained state with respect to both Co/CoO bilayers and O-implanted Co films with a Gaussian-like O depth profile. This underlines the great potential of ion implantation to tailor the magnetic properties by controllably modifying the local microstructure through tailored implantation profiles.