Hysteresis loops of Co–Pt perpendicular magnetic multilayers

Abstract

We develop a phenomenological model to study magnetic hysteresis in two samplesdesigned as possible perpendicular recording media. A stochastic cellular automaton modelcaptures cooperative behaviour in the nucleation of magnetic domains. We show how thissimple model turns broad hysteresis loops into loops with sharp drops like thoseobserved in these samples, and explains their unusual features. We also present, andexperimentally verify, predictions of this model, such as the temperature dependence of thehysteresis loop shape, and the existence and time dependence of drops in first-orderreversal curves. We suggest how insights from this model may apply more generally.