Materials

Ferromagnet-semiconductor hybrid structures are an important possible building block for future spintronic devices. For ferromagnet-semiconductor hybrid structures, the compatibility of the constituent materials regarding mismatch or mismatch accomodation, thermal stability of the interface, as well as high Curie temperatures above room-temperature are of particular interest. The films often show intriguing magnetic properties, which are so far not completely understood. Our studies aim at reaching a comprehensive understanding of the epitaxial growth, the structure and properties of ferromagnetic films grown on semiconductors.

Heusler alloys

Heusler alloys are of particular interest because of their high Curie temperatures, close lattice-matching and their expected half-metallic behavior, which makes them promising as a room-temperature spin-injection source.

Co₂FeSi is theoretically predicted to be a half-metal with a high Curie temperature (980 K) and is closely lattice-matched to GaAs. We focus on the epitaxial growth of Co₂FeSi films by molecular-beam epitaxy on various GaAs and Si substrate orientations. The comprehensive understanding of the correlation between structural as well as interface perfection and the  electrical and magnetic properties of such hybrid structures will allow us to design spin-injection devices with an optimized performance.

Further studies are devoted to Fe₃Si film epitaxially grown on GaAs substrates.