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 T_S 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 T_S = 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 T_S 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.