Berlin 2008 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Magnetic Thin Films I
MA 15.6: Vortrag
Dienstag, 26. Februar 2008, 11:45–12:00, H 1012
Influences of thermal treatment on the As valence in MnAs thin films on GaAs substrate — •Benjamin Schmid1, Sebastian Engelbrecht1, Markus Paul1, Michael Sing1, Jan Wenisch2, Charles Gould2, Karl Brunner2, Lorenz Molenkamp2, Wolfgang Drube3, and Ralph Claessen1 — 1Experimentelle Physik IV, Universität Würzburg, Würzburg, Germany — 2Experimentelle Physik III, Universität Würzburg, Würzburg, Germany — 3HASYLAB, DESY, Hamburg
Manganese arsenide has attracted a great deal of interest as a possible candidate for ferromagnet-semiconductor heterostructures. Compared to diluted magnetic semiconductors it offers advantages such as compatibility to gallium arsenide and a Curie-temperature as high as 317 K. While it has been shown that the structural and magnetic properties can be improved by post-growth annealing under As flux the microscopic origin at work is still unclear.
Using photoemission spectroscopy various chemcial states can be distinguished. By going to the hard X-ray regime the volume sensitivity is significantly increased. Thus it is possible to observe the intrinsic electronic structure despite surface contamination. On the other hand, informations on surface states can be regained by angle dependent measurements. In order to obtain oxygen and carbon free surfaces for future industrial and scientific purposes the effects of in situ annealing with and without As flux are discussed. The relative amounts of covalently bonded, elemental and oxidized As depend dramatically on sample treatment and in turn determine the magnetic properties.