On the relationship between the hysteresis loop shift and the dipolar interactions in hard–soft nanocomposite samples

Abstract We report on the hysteretic and relaxational behavior of Fe–Ba hexaferrite nanocomposite samples prepared by ball milling. This includes data on the temperature dependence of the coercive force, on the relationship between the field evolution of the isothermal and the demagnetization remanences and on the time evolution of the magnetization at those remanences. Our most remarkable result corresponds to the observation, at room temperature and without field cooling the samples, of a displacement (in the sense of the negative fields) of the hysteresis loops measured under a maximum applied field of 0.8 T. The magnitude of that shift oscillates when the Fe content changes. Our results are analyzed in terms of the occurrence of interphase dipolar interactions.