Magnetism of nanoscale CoCrPt-SiO2 films in geometrically confined dimensions
Supported by the DFG: FA 314/7-1.
Prof. Dr. Manfred Albrecht (TU Chemnitz)
Prof. Dr. Thomas Schrefl (Univ. Sheffield)
The project aims at the understanding of the magnetization reversal behavior, the switching field distribution and the spin dynamics, especially the magnetic damping, of granular CoCrPt-SiO2 films with perpendicular anisotropy in geometrically confined dimensions on locally curved surfaces (see Fig. 1). The essential parameter for the collective behaviour of the individual grains is the intergranular exchange coupling, which can be tailored either by the introduction of SiO2 at the grain boundaries or by means of ion irradiation of the deposited films (see Fig. 2). By means of the predefined surface morphology (SiO2 particle monolayer or ion erosion template) an additional “interdot”-coupling is introduced which is connected to the length scale of the template and defines the magnetic active region (dot). The local curvature of the substrate leads to an exchange decoupling of the neighboring dots as well as to a local variation of the anisotropy distribution. The control of the template length scale allows to investigate the magnetic properties as a function of the magnetic active unit. As a long term perspective the preparation of a single grain per pre-patterning unit is envisaged. This could be of enormous technological importance. All experimental investigations are complemented by micromagnetic simulations.
Fig.1: a) Cross-sectional TEM image of both types of templates (SiO2: sphere diameter 160 nm (top), GaSb template: period 35 nm (bottom)). The difference in morphology and local curvature of both template types is easily observed. b) Sketch of the different template topographies.
|Fig. 2: Coercive field as a function of the ion induced damage of a CoCrPt-SiO2 film using Ne (black) or Co (red) ions. The inset shows exemplary magnetization reversal curves before and after Co implantation. MFM images of the domain configuration in the demagnetized state are shown for Co implantation (left) and Ne implantation (right).|
D. K. Ball, K. Lenz, M. Fritzsche, G. Varvaro, S. Günther, P. Krone, D. Makarov, A. Mücklich, S. Facsko, J. Fassbender, and M. Albrecht
Nanotechnology, in print (2014)
Nanocap arrays of granular CoCrPt:SiO2 films on silica particles: tailoring of the magnetic properties by Co+ irradiation
P. Krone, C. Brombacher, D. Makarov, K. Lenz, D. Ball, F. Springer, H. Rohrmann, J. Fassbender, M. Albrecht
Nanotechnology 21, 38 (2010).
Magnetic patterning by means of ion irradiation and implantation
J. Fassbender, J. McCord
J. Magn. Magn. Mater. 320, 579 (2008)
Tailoring Magnetism by Light Ion Irradiation
J. Fassbender, D. Ravelosona, Y. Samson
J. Phys. D: Applied Physics 37, R179 (2004).