A Preisach analysis of irreversibility in a particulate thin film: Fe-Al2O3

We present measurements of some of the principal response functions of a th in film of nanodimensional Fe particles embedded in Al2O3, specifically the temperature dependence of the moment measured under field cooled and zero field cooled conditions at temperatures between 5 K less than or equal to T less than or equal to 300 K in a low applied field h(a) = 10 Oe, and the m ajor hysteresis loop measured at T = 5 K in applied fields between -2000 Oe less than or equal to 5 h(n) less than or equal to +2000 Oe. The data were analyzed within the framework of a generalized version of the Preisach mod el of hysteresis, which treats all magnetic systems as ensembles of interac ting bistable Barkhausen elements, and which includes both thermal barrier relaxation effects and critical effects. Numerical simulations based on the model are able to replicate the principal structural features of the exper imental data, and allow us to extract the characteristics of the bistable e lements, specifically their moments mu, their coercive fields h(c) and thei r interaction fields h(i).