Magnetization reversal process of 360 degree -domain walls observed by magnetic force microscope in exchange-biased NiFe films

The magnetization reversal process of an exchange biased NiFe layer was investigated around 360 degree -domain wall loops by magnetic force microscopy (MFM) in Glass/Ta(10 nm)/NiFe(7.2 nm)/FeMn(8.0 nm)/Ta(5 nm). The sample was prepared by rf-magnetron sputtering and characterized with vibrating sample magnetometer (VSM). The reversal process was performed dominantly by rotation due to a large unidirectional anisotropy and probably due to a substantial orientation deviation of the local pinning field from the easy axis of the NiFe-layer. The magnetization reversal process performed by wall nucleation and growth was also observed. The dominant reversal mechanism in the exchange-biased ferromagnetic layer was discussed in terms of anisotropy energy.