Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 46: MagneticThin Films II

MA 46.2: Vortrag

Donnerstag, 29. März 2012, 15:15–15:30, EB 202

Magnetic tunnel junctions based on zinc ferrite and cobalt — •Michael Bonholzer, Kerstin Brachwitz, Katja Mexner, Jan Zippel, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Linnéstraße 5, 04103 Leipzig, Germany

Magnetic tunnel junctions (MTJs) could play an important role in future computer architecture and spintronic systems. The oxide zinc ferrite shows a good tunability in magnetic and electric properties and is a promising candidate for oxide MTJ structures. We present magnetic tunnel junctions built from zinc ferrite, magnesium oxide and cobalt. Zinc ferrite, acting as soft magnetic bottom electrode, was grown by pulsed laser deposition (PLD) on MgO substrates. The thin films (d≈200 nm) were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), SQUID- and Hall-effect measurements and optimized in their conductivity (σ≈50 S/m) and surface roughness (rms ≈0.2 nm). The thickness of the barrier material magnesium oxide was varied between 5 and 60 nm. It was also grown by PLD and the surface and stuctural properties were measured by AFM and RHEED. The cobalt top-electrode, which serves as hard magnetic electrode, was fabricated by thermal evaporation. The MTJ-structure was defined by multi-step photolitography with wet-chemical etching, using crossed-over masks in order to limit the contact area to 50×50 µ m². Current-voltage measurements in dependence of an external magnetic field were performed and a tunnel-magnetoresistance (TMR) up to 65% was found.