Dresden 2009 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)
MA 40.102: Poster
Freitag, 27. März 2009, 11:00–14:00, P1A
Dielectric Breakdown and inelastic electron tinneling spectroscopy of top pinned and bottom pinned Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions — •Ayaz Arif Khan, Jan Schmalhorst, Karsten Rott, Andy Thomas, and Günter Reiss — Thin films and physics of Nano structures, Department of Physics, Bielefeld university, P. O. Box 100131, 33501 Bielefeld germany.
We present a detailed investigation into the intrinsic tunnel barrier reliability in Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions (MTJ). The intrinsic reliability is measured as the ramped breakdown voltage (Vbd) at room temperature for both positive and negative polarity. The measurements were done for two types of junctions: one set of junctions had exchange biased (pinned) bottom electrodes, one set exchange biased (pinned) top electrodes with an additional artificial ferrimagnet. We found a significant polarity dependence in the dielectric breakdown: top as well as bottom pinned tunnel junctions showed higher breakdown voltage when the top electrode was biased positively compared to negative bias. In contrast to this the differential resistance dV/dI−V spectra revealed an asymmetry for the top pinned junctions which was reversed in comparison to the bottom pinned system. This indicates that both asymmetries have different origins. Additionally the bottom pinned junctions showed in general slightly lower breakdown voltages and stronger magnon excitation in the inelastic electron tunneling d2I/dV2−V spectra than the top pinned junctions.Possible reasons for these correlations are discussed.