Training effect of exchange-bias bilayers within the domain state model

Abstract

An investigation of the temperature dependence of the training effect of various exchange coupled bilayers with different types of anisotropy is presented. We use an atomistic model for the magnetic interactions within a classical Heisenberg spin Hamiltonian. In general, the behavior of the exchange-bias field is separated into low- and high-temperature regions. This separation is made according to the trend of exchange-bias field after the second hysteresis loop and the parameters of the power-law fit for these fields. It is found that with increasing antiferromagnetic thickness, systems follow the same temperature trend but with lower values of the exchange-bias field and a weaker training effect. This is due to the fact that thicker antiferromagnetic layers lead to increased stability of the antiferromagnetic domains. Also, the behavior of the coercive fields is investigated, concluding that the training effect occurs predominantly in the first half of the hysteresis loop.