LAUSR

Abstract The exchange bias effect in nano-objects is modelled by adding to the magnetic energy two terms allowing for two kinds of anisotropy, viz. a fixed-axis and a rotatable one. The signature of the second contribution is an isotropic shift H R A of the ferromagnetic resonance field. The temperature dependence of H RA that is due to the superparamagnetic theory is obtained in the framework of kinetic theory. Our analysis predicts that the temperature behaviors of H R A are qualitatively different depending on the possible symmetry type of the rotatable anisotropy energy term: unidirectional or uniaxial.