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 14.87: Poster

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

Modelling the magnetization hysteresis and ac susceptibility in a superferromagnetic system — •O. Petracic, X. Chen, O. Sichelschmidt, Ch. Binek, and W. Kleemann — Laboratorium für Angewandte Physik, Gerhard-Mercator-Universität Duisburg, D-47048 Duisburg

We report on kinetic model simulations of domain wall motion in a superferromagnetic system. The studies are motivated by our experimental results on the discontinuous magnetic multilayer Co₈₀Fe₂₀(1.4 nm)/Al₂O₃(3nm)₁₀. The CoFe forms nearly spherical single-domain particles embedded in the Al₂O₃ matrix. The inter-particle distances are small enough to assume ferromagnetic exchange interaction besides the dipole-dipole interaction. The dynamical and hysteretic properties of this so called superferromagnet can be understood in the framework of domain wall motion in an impure ferromagnet. The simulations are based on a field and temperature dependent domain wall velocity including creep and viscous motion as elaborated by Nattermann et al. (2001). The magnetization hysteresis as well as the ac susceptibility, χ′ − i χ″, can be extracted and compared to our experimental findings. Particularly interesting is the analysis of the Cole-Cole plots, χ″ vs. χ′, which usually serve as dynamic fingerprints.