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MA: Magnetismus
MA 10: Poster : Dünne Schichten(1-21),Spinabh.Transp.(22-39),Exch.Bias(40-51),Spindyn.(52-55),Mikromag.(56-66),Partikel(67-74),Abb.Verf.(75-77),Oberfl.+Spinelektr.+Elektr.Theo+Mikromag(75-87),PÜ+Aniso+Werkst/Leg.(88-103),Mol.Mag.+N-dim+Messm.+Postdead(104-111
MA 10.24: Poster
Dienstag, 12. März 2002, 15:00–19:00, Bereich A
Magnetotransport and microstructure of annealed magnetic tunnel junctions — •J. Schmalhorst1, H. Brückl1, G. Reiss1, G. Gieres2, and J. Wecker2 — 1University of Bielefeld, Dept. of Physics, Nano Device Group, P.O. Box 100131, 33501 Bielefeld, Germany — 2Siemens AG, Corporate Technology CT MM 1, P.O. Box 3220, 91050 Erlangen, Germany
We investigated the structural, the magnetic, the magnetotransport and the tunneling properties of CoFe/Al2O3/Ni81Fe19 junctions with an artificial ferrimagnet as a pinning layer for different Al thickness and oxidation time after isochronal annealing up to 500oC. The main purpose of these experiments is to find relations between the structural changes upon annealing and the modifications of the physical magnetotransport and barrier properties, which could also be important for the further application of such tunneling elements in spinelectronics. The tunneling magnetoresistance (TMR) shows a strong increase up to 37% after annealing at 300oC accompanied by an improvement of the dielectric stability and the voltage dependence of the TMR. At higher temperature the TMR starts to decrease. The dielectric stability remains good up to annealing temperatures of 500oC, indicating an excellent thermal stability of the Al2O3 barrier. All results can be related to thermally induced structural changes of the microstructure which have been determined by Auger Depth Profiling and complementary methods.