PUB - Publikationen an der Universität Bielefeld

We have integrated Co2MnSi as a representative of the full-Heusler compound family as one magnetic electrode into technological relevant magnetic tunnel junctions. The preparation strategy has been chosen so as to sputter Co2MnSi at room temperature onto a V-buffer layer, which assists in (110) texture formation, and to deposit the Al-barrier layer directly thereafter. After plasma oxidizing the Al-barrier layer subsequent annealing leads (1) to the texture formation and (2) to the appropriate atomic ordering within the Co2MnSi and (3) homogenizes the AlOx-barrier. The resulting magnetoresistance of the Co2MnSi containing magnetic tunnel junctions has been determined as a function of temperature. At a bias voltage of 1 mV a magnetoresistance of 94.6% has been realized at 20 K leading to a spin polarization of 65.5%. Furthermore, the microstructural as well as magnetic quality of the Co2MnSi/AlOx-barrier interface has been investigated in detail. Additionally, the problem of antisite formation at the Co2MnSi/AlOx-barrier interface is experimentally addressed by intercalating thin Co layers in between the Heusler layer and the AlOx barrier. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.