We investigate magnetization reversal and thermal stability (energy barriers) properties of composite media, for a broad range of saturation magnetization values, comparing the case of individual grain and muitigrain systems in order to assess the effect of intergranular interactions. For the hard phase we incorporate partially ordered FePt model with realistic representation of exchange interactions as well as a "future recording media" with high anisotropy and low magnetization. The results are presented as a function of the interfacial exchange parameter. We demonstrate that the energy barriers of an individual grain and muitigrain thin film show different behavior due to the domain wall formation at the remanence for thin films with low magnetization soft layer. The individual grain presents the most favorable figure of merit for large soft layer magnetization. In contrast, for the muitigrain thin film, the best performance corresponds to the case of both low soft and hard layer magnetizations.
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