Tuning the training effect in exchange biased NiO∕Ni bilayers

Exchange bias is reduced upon magnetic field cycling, which is referred to as the training effect. Here, large fields of 10kOe⁠, both out of plane and in plane, are applied to tune the training effect in exchange biased NiO∕Ni bilayers. It is found that the large fields, especially for the out-of-plane field, accelerate the training effect, i.e., the exchange bias field decreases abruptly, while the coercivity increases at first and then decreases. These phenomena could be caused by field induced changes in the NiO domain structure, which is supported by measurements of consecutive hysteresis loops with increasing fields.