Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)
MA 40.67: Poster
Freitag, 27. März 2009, 11:00–14:00, P1A
Fabrication and analysis of Fe and Fe/MgO films on the GaAs(110) cleaved edge of an LED structure for spin injection — •Hasmik Harutyunyan1, Carsten Godde1, Sani Noor1, Ulrich Köhler1, Arne Ludwig2, Dirk Reuter2, and Andreas D. Wieck2 — 1Institut für Experimentalphysik IV, AG Oberflächen, Ruhr-Universität Bochum, Germany — 2Lehrstuhl für angewandte Festkörperphysik, Ruhr-Universität Bochum, Germany
This project’s aim is the spin injection via Fe and Fe/MgO on the GaAs(110) cleaved edge which can be detected optically by an LED structure in the sample. The geometry of cleaved edge samples allows a spin injection perpendicular to the quantum well in the LED structure using an in plane magnetized Fe film. The conductivity mismatch is minimized either by the Schottky barrier of the Fe/GaAs interface or by use of MgO as a tunnelling barrier. This contribution focuses on the technical aspects of the cleaving and evaporation processes which are not trivial especially due to the dangers of short-circuiting the LED structure. Structured samples are cleaved in UHV. Cleaved edge overgrowth (CEO) is carried out under variable angles with respect to the cleavage surface. Angular dependent MOKE measurements have been performed in both cases. For Fe/GaAs, the easy axis is [001] with a high remanence. However, under the use of an MgO tunnelling barrier, the easy axis rotates by 90∘ into the [110]. Photoluminescence has been shown for electrons travelling from the ferromagnetic contact into the semiconductor. Optical and therewith spin polarisation has yet to be demonstrated.