Journal of Superconductivity and Novel Magnetism   2016 年 29 卷 4 期

2016.04.01

For perpendicular exchange-biased IrMn/Pt/ Co/Pt multilayers with bidomain state, double hysteresis loops (DHLs) are achieved. It is found that exchange bias field and coercivity in full loop and two subloops??? training show different dependencies on the cycle number. Further studies show that the negative-biased (positive-biased) subloop measurement will influence training effect of the positive-biased (negative-biased) subloop, acting as a recovery process. This recovery procedure is different from the conventional ways, i.e., by applying a magnetic field perpendicular to the initial pinning direction or by leaving the sample alone for several days without any applied magnetic fields. This recovery effect can be explained by the re-rotation of antiferromagnet (AFM) spins after corresponding subloop magnetic moment reversal during the full loop measurement, which cannot happen during the subloop measurement.