Regensburg 2010 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 6: Magnetic Thin Films I (Heusler Alloys)
MA 6.13: Vortrag
Montag, 22. März 2010, 17:45–18:00, H10
Interface properties of spin injection systems and tunnel barrier systems: Fe3Si on GaAs(001) and MgO(001) — •Sergey Makarov, Frank Stromberg, Bernhard Krumme, Claudia Weis, Werner Keune, and Heiko Wende — Fakultät für Physik and CeNIDE, Universität Duisburg-Essen
For spintronic applications, not only the charge transfer to the semiconductor, but also the spins of the electrons are of interest. Ferromagnet/semiconductor interfaces allow controlling the spin orientation of injected electrons. The degree of spin polarisation depends on the structural quality of the interface. Furthermore, the spin injection efficiency can be improved by introducing a tunnel barrier at the interface.
The quasi-Heusler system Fe3Si is a promising candidate for such applications. It grows well ordered on MgO(001) with a low lattice mismatch to semiconducting GaAs(001). We have investigated the chemical ordering of Fe3Si by conversion electron Mössbauer spectroscopy (CEMS) using the 57Fe tracer layer technique. From CEMS we obtain the long-range order parameters S(D03) and S(B2) together with the Si concentration. Strong interdiffusion occurs at the Fe3Si/GaAs interface. Introducing a MgO tunnel barrier hinders the interdiffusion. Fe3Si/MgO/GaAs(001) suprisingly shows an almost ordered D03-structure with 26% Si-content. However, the 57Fe3Si tracer layer at the MgO-buffer layer displays the B2-ordered structure with randomly distributed Si atoms on Fe sites. On the MgO tunnel barrier, the chemical order of Fe3Si is comparable to Fe3Si grown directly on a MgO(001) single crystal. – Supported by the DFG (Sfb491).