Regensburg 2002 – wissenschaftliches Programm
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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 10.45: Poster
Dienstag, 12. März 2002, 15:00–19:00, Bereich A
Perpendicular Exchange Bias in CoO/Co Bilayers — •Florin Radu, Kurt Westerholt, and Hartmut Zabel — Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany
We report observations of perpendicular exchange bias in CoO/Co thin films. The sample was prepared by rf-sputtering. A Co (FM, Tc=1403 K) layer was grown on a sapphire substrate and then, by oxidation in air a CoO (AFM, TN=291 K) layer was formed on the top. The system is cooled in an applied magnetic field of Ha= − 2000 Oe perpendicular to the sample surface through the Neel temperature of the antiferromagnet to different temperatures where the magnetic hysteresis loop is measured. The temperature dependence of the exchange bias and coercive field are measured by SQUID magnetometry. While the exchange bias shows a common behavior, i. e. increasing exchange field starting from the blocking temperature (TB=187 K) on, the coercive field has a striking behavior: it shows a strong enhancement at the blocking temperature. It increase from Hc=160 Oe at T=240 K reach the maximum value of Hc=300 Oe at TB and decreasess again to Hc=160 Oe at T=120 K. From this temperature on it increases again steadly up to Hc=270 Oe at T= 5 K. The dependence on the cooling field is shown, as well.
This work is supported by SFB 491.