FORC Analysis of Size Effects in Ising-Type Models of Disordered Magnets

The intensive use of nanosized particles in modern technologies has increasingly raised the problem of the surface effect in the total magnetic moment of the particle. As the size of the particle decreases the weight of surface moments in the total moment increases. The Ising-type models have been used in the study of thermal size effects, but no systematic analysis was made on the hysteretic properties of nanostructured systems. In this paper we present an original approach, based on the first order reversal curves (FORC) method, on the size effect in two of the most used models of disordered magnets: the random field Ising model (RFIM) and the Edwards Anderson Ising spin glass (EASG), that can describe complex magnetization processes at a constant temperature.