Study on Magnetic Domain Structure and Magnetic Domain Dynamics in Co/Ni Multilayer Thin Films with or without IrMn Layer

In this study, we report the experimental observation of the magnetic domain structure and magnetic domain dynamics in Co/Ni multilayer thin films with or without antiferromagnetic IrMn layer, respectively. First, as a result of observing the magnetic domain structure using a magnetic force microscopy, it is found that the magnetic domain size decreases as the Co/Ni layer thickness increases, and that the samples with the IrMn layer have the larger magnetic domain sizes than the samples without the IrMn layer. Also, using a magneto-optical Kerr magnetometer capable of measuring the magnetic viscosity curve, we find that the magnetization reversal phenomenon in all samples is explained by the thermally activated model. Additionally, it is found that the samples with the IrMn layer have the larger activation volumes than the samples without the IrMn layer.