PhD thesis

I worked at the Institute of Applied Physics in Hamburg on epitaxial nanostructures from 2007 to 2011, where I received my PhD for my thesis on Masking technique for the generation of epitaxial nanostructures and modification of magnetic anisotropy of ultrathin Co/Au(111) films by ion etching. The thesis analyses ultra-thin epitaxial Co/Au(111) structures and their magnetic anisotropic behavior.

In order to study epitaxial nanostructures, I developed a method to fabricate structures using a mask technique. The idea is to cut these masks out of a silicon nitride membrane using a focused ion beam. Fixed on a support frame they can be placed on the single crystal sample in an ultra-high vacuum. I used thermal evaporation to deposite (magnetic) material, e.g. cobalt, on the substrate, where epitaxial nanostructures grow. These masks can be reused several times, so structures with the same lateral dimensions but different layer thicknesses can be fabricated.

I investigated the structures produced this way with respect to their magnetic properties, in particular magnetic anisotropy. I measured the magnetic properties of the samples in-situ with the magneto-optical Kerr effect.

Part of this work was the conception, the construction as well as the set-up of the ultra-high vacuum aparatus for the fabrication process.

Furthermore, I analyzed the magnetic anisotropy of extended Co/Au(111) films ablated by ion bombardment. In this process, the surface of the epitaxial film is changed and the surface anisotropy is reduced. As a result, the perpendicular magnetization direction present at low film thicknesses is lost. At low energies, however, it is possible to ablate the films in such a way that the perpendicular anisotropy is not completely lost and perpendicular magnetization is again achieved.

My thesis is puplished online at the Staats- und Universit├Ątsbibliothek Hamburg.