Regensburg 2000 – wissenschaftliches Programm
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AM: Magnetismus
AM 13: Postersitzung: Dünne Schichten (1–22), Magnetowiderstand (23–40), Phasenübergänge (41–55), Mikromagnetismus (56–68), Spektroskopie (69–77), Nanokristalline Materialien (78–82), Anisotropie (83–86), Schmelzen (87–90), Weitere Bereiche (91–100)
AM 13.30: Poster
Dienstag, 28. März 2000, 16:00–20:00, A
Investigation on the stability of ferromagnetic tunnel junctions — •R. Kinder1,2, U. K. Klostermann1,2, S. Zoll2, J. Bangert2, HAM v. d. Berg2, and J. Wecker2 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93040 Regensburg — 2Siemens AG, ZT MF 1, Paul-Gossen-Str. 100, D-91052 Erlangen
Magnetic tunnel junctions (MTJ) show a resistance depending on the relative orientation of the magnetisations of the two magnetic counter electrodes. Therefore they are a promising candidate for the Magnetic Random Access Memory (MRAM).
Here we report on the observation of fatigue effects in supra- and sub-micron ferromagnetic tunnel junctions fabricated by optical and electron beam lithography. For the rigid magnetic reference layer a single Co-layer or an artificial antiferromagnet (AAF) with Co on top was used. The soft detection layer, separated by a thin Al2O3 barrier, consisted of Py or Fe. The TMR effect was measured by a four point measurement setup. Depending on the multilayer stack different TMR effects were achieved with a maximum of >20% for a certain aluminum thickness and plasma oxidation time. Some measurements show significant changes in the tunnel resistance with increasing measurement time, which could likely be correlated to possible degradation effects in the tunnel barrier itself. We also present data on the TMR values and the switching behaviour of the magnetic tunnel junctions for repeated switching in an external magnetic field in the order of 104 cycles.