Andrea Nielsen was member of the Gross group at WMI as a Ph.D. student between 2005 and 2009.

Ph.D. Thesis: Magnetit - ein Material für die Spinelektronik  (2009)

In her Ph.D. thesis, Andrea Nielsen studied the properties of magnetite-based thin film structures, as the halfmetallic ferrimagnet magnetite has a high Curie temperature of 860K and, therefore, is interesting for spintronics. She was growing magnetite films with different orientations by laser molecular beam epitaxy. Like for many metallic systems, she found a scaling relation between the Hall and longitudinal conductivity with an exponent of 5/3. By magnetotransort measurements performed on magnetite films as well as on magnetite based tunnel junctions with different magnetic field orientations she also determined the magnetic anisotropy constants. In order to realize spin injection into a semiconductor, she has grown magnetite epitaxially on ZnO for the first time and could realize experiments for a detection of spin injection from magnetite into ZnO.