Dresden 2011 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 63: Poster II (Surface Magnetism/ Magnetic Imaging/ Topological Insulators/ Spin Structures and Magnetic Phase Transitions/ Graphene/ Magnetic Thin Films/ Magnetic Semiconductors/ Magnetic Half-metals and Oxides/ Spin-dependent Transport/ Spin Excitations and Spin Torque/ Spin Injection and Spin Currents in Heterostructures/ Spintronics/ Magnetic Storage and Applications)
MA 63.52: Poster
Freitag, 18. März 2011, 11:00–14:00, P2
Ferromagnetic Heusler alloy Co2FeSi films on GaAs(110) substrates — •Thomas Hentschel, Bernd Jenichen, Achim Trampert, and Jens Herfort — Paul-Drude-Institut Berlin, Hausvogteiplatz 5-7, 10117 Berlin, Germany
Ferromagnetic Heusler alloys may be promising material candidates for spintronic devices due to a theoretically full spin polarization at the Fermi edge. We have investigated the Heusler alloy Co2FeSi grown by molecular beam epitaxy on GaAs(110) for different substrate temperatures TS with respect to the structural and magnetic properties. The (110) ferromagnet/semiconductor (FM/SC) interface is predicted to maintain the half-metallic behaviour. Furthermore the (110) orientation reveals a significantly higher spin-lifetime in the semiconductor than its (001) counterpart.
We found ferromagnetic films entirely free of dislocations and an interface roughness below 1 nm up to TS = 225 ∘C. The films exhibit an in-plane uniaxial magnetic anisotropy with an easy axis along the [110] and a hard one along the [001] direction. With increasing TS the hard [001] axis shifts into an intermediate one, while the easy axis remains stable but shows higher coercitive fields, indicating the formation of crystal defects. X-ray diffraction measurements reveal the lattice parameter expected for the correct composition. If the film thickness is continuously reduced from 40 to 4 nm, the uniaxial contribution increases. This gives evidence that the FM/SC interface plays an important role in the magnetic behaviour.