Recovery of the training effect in exchange bias systems within a coherent rotation model

Abstract

Brems et al., [Phys. Rev. Lett. 95, 157202 (2005)] reported that the training effect in Co/CoO bilayers can be recovered by performing a hysteresis loop with an in-plane field perpendicular to the initial cooling field without raising the temperature above the N\'eel temperature. We performed numerical simulations of this effect within the coherent rotation model with multiple antiferromagnetic (AFM) easy axes. Both the ferromagnetic (FM) and AFM layers are divided into multi domains, and each FM domain couples with one AFM domain. In combination with the anisotropic magnetoresistance calculation, we find a strong dependence of the training recovery effect on the magnitude of the perpendicular field, in good agreement with the experimental findings.