Berlin 2024 – scientific programme
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MA: Fachverband Magnetismus
MA 20: Poster I
MA 20.35: Poster
Tuesday, March 19, 2024, 16:30–19:00, Poster A
Modeling the training effect in exchange-biased bilayers for large numbers of magnetization reversal cycles — Johannes Fiedler1, Martin Wortmann2, Tomasz Blachowicz3, and •Andrea Ehrmann1 — 1Bielefeld University of Applied Sciences and Arts, Faculty of Engineering and Mathematics, Bielefeld, Germany — 2Bielefeld University, Faculty of Physics, Bielefeld, Germany — 3Silesian University of Technology, Institute of Physics - Center for Science and Education, Gliwice, Poland
The exchange bias (EB) is a unidirectional anisotropy which occurs, e.g., upon field-cooling ferromagnet/antiferromagnet systems. In many material systems, the EB field is reduced from one hysteresis loop to the next measurement. This so-called training effect (TE) has been investigated in experiments and by means of theoretical efforts by many research groups. The reduction of the EB field as a result of subsequent magnetization reversal processes is often fitted by a power law, usually with the exception of n=1, or with an equation based on the discretized Landau-Khalatnikov (LK) equation, as firstly suggested by Binek. Few other models, usually with more fitting parameters, have been proposed yet. Here we show that for large numbers of subsequent magnetization reversal processes in Co/CoO thin film samples, a modified power law or a logarithmic fit can model the training effect significantly better than the above mentioned, commonly used models.
Keywords: exchange bias; training effect; power law; Binek fit; Co/CoO