Regensburg 2007 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 26: Exchange Bias
MA 26.6: Vortrag
Donnerstag, 29. März 2007, 16:30–16:45, H10
Analysis of effective magnetic anisotropies in exchange-coupled bilayer systems — •Daniel Markó1,2, Jeffrey McCord2, Rudolf Schäfer2, Rainer Kaltofen2, and Ludwig Schultz2 — 1Forschungszentrum Dresden-Rossendorf, Institut für Ionenstrahlphysik und Materialforschung, Bautzner Landstr. 128, D-01328 Dresden — 2Leibniz-Institut für Festkörper- und Werkstoffforschung Dresden, Helmholtzstraße 20, D-01069 Dresden
We have investigated the effective magnetic anisotropies in FM/AFM exchange-coupled Ni81Fe19/Ir19Mn81 bilayers with constant FM and varying AFM layer thickness. The samples have been prepared by either RF or DC magnetron sputtering to study the effect of different AFM grain sizes. In addition, the influence of thermally activated processes in the AFM layer has been investigated by annealing the samples with varying temperature, durations, and cooling rates. By using two magnetometric methods with different experimental time scales, a separation of different anisotropy contributions was possible. Quasistatic measurements yield the coercivity HC and the exchange-bias field Heb,ea. From the dynamic experiment the exchange-bias field Heb,dyn, the rotatable anisotropy Hrot, the ferromagnetic resonance frequency fres, and the effective magnetic damping parameter α were determined. Moreover, magnetization processes have been observed by means of Kerr microscopy. Our experimental results were compared with models for exchange-bias and are in agreement with the models of Malozemoff, Fulcomer and Charap, and McMichael and Stiles.