Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 13: Spinabh
ängiger Transport I
MA 13.2: Vortrag
Samstag, 5. März 2005, 11:00–11:15, TU EMH225
Optimization and characterization of Co2MnGe based magnetic tunneling junctions — •Erik Verduijn and Kurt Westerholt — Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum
Heusler compounds are materials of great potential in the field of spintronics due to their predicted 100% spin polarization at the Fermi level. We have studied the spin polarization of such Heusler compounds, in particular the Co2MnGe compound via the magnetotransport properties of magnetic tunneling junctions (MTJs) with Heusler as base electrode and Co as counter electrode. Optimization of the tunnel barrier layer, surface roughness of the base electrode and magnetic properties are critical to the quality of the MTJs and our approach to these issues will be discussed in some detail. Magnetotransport measurements indicate the junctions fullfill all properties expected of good quality MTJs. Furthermore measurements of the TMR effect of these junctions indicate the Co2MnGe layers we have prepared to have a significant spin polarization, at least as large as that of elemental Co. Although this spin polarization is far from the predicted 100% it is significant, considering the difficulties in both growth of the Heusler layer and succesfull intergration into a MTJ, that any spin polarization has been measured whatsoever. These difficulties e.g. magnetic and crystalline properties of the Heusler layers, surface roughness and interdiffusion and their relation to the measured spin polarization will be presented.