Crossover from reversible to irreversible magnetic exchange-spring processes in antiferromagnetically exchange-coupled soft/hard bilayer structures

摘要

The demagnetization processes of antiferromagnetically exchange-coupled soft/hard bilayer structures have been studied using a one-dimensional atomic chain model, taking into account the anisotropies of both soft and hard layers. It is found that for bilayer structures with strong interfacial exchange coupling, the demagnetization process exhibits typical reversible magnetic exchange-spring behavior. However, as the strength of the interfacial exchange coupling is decreased, there is a crossover point Ashc, after which the process becomes irreversible. The phase diagram of reversible and irreversible exchange-spring processes is mapped in Ash and Ns plane, where Ash and Ns are the interfacial exchange coupling and soft layer thickness, respectively. The thickness dependence of the bending field, which characterizes the onset of the exchange spring in the soft layer, is numerically examined and compared with analytical models.