Dresden 2003 – wissenschaftliches Programm

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MA: Magnetismus

MA 14: Poster: Schichten(1-31), Spinabh.Trsp.(32-47), Exch.Bias(48-54), Spindyn.(55-64), Mikromag.(65-76), Partikel(77-88), Oflmag.(89-92), Spinelektr.(93-98), Elektr.Theo.(99-103), Mikromag+PhasÜ+Aniso.(104-122), MagnMat.(123-134), Messm+Mol-Mag.(135-139), Kondo(140-151)

MA 14.53: Poster

Dienstag, 25. März 2003, 15:15–19:15, Zelt

Exchange coupling in Fe/NiO/Co film studied by soft-X-ray resonant magnetic reflectivity — •Oksana Zaharko¹, Peter M. Oppeneer², H. Grimmer¹, M. Horisberger¹, Hans-Christoph Mertins³, Dirk Abramsohn³, Franz Schäfers³, A. Bill¹, and H.-B. Braun¹ — ¹PSI Villigen — ²IFW Dresden — ³BESSY Berlin

The magnetic interactions and oxidation effects in a Fe/NiO/Co trilayer are studied element-selectively by soft-x-ray resonant magnetic reflectivity (T-MOKE) at the L₃ edges of Fe, Co, and Ni. Oxidation of Fe and Co at the interfaces is observed from the clear multiplet structure. The measured x-ray Kerr loops reveal information on the magnetization reversal and coupling of the spins of metallic and oxidized states of the various 3d atoms. The coupling between oxidized and metallic Co spins is ferromagnetic, whereas for Fe both, antiferromagnetic and perpendicular couplings between oxidized and metallic states are observed. An excess Ni magnetic moment appears after cooling through the Néel temperature of NiO. One part of the excess Ni spins is ferromagnetically coupled to the metallic Fe and Co spins and exhibits a conventional hysteresis loop. Another part is formed at the interface as follows from the asymmetry of the Kerr loop of oxidized Co spins. Competing interactions lead to frustrated magnetization at the Fe/NiO interface and cause a tilt of the Fe spins away from the field direction, which manifests itself by characteristic humps in the Kerr loops of metallic and oxidized Fe states.