TEM INVESTIGATION OF THE MAGNETIZATION PROCESSES IN EXCHANGE-COUPLED MULTILAYER FILMS

The magnetisation reversal processes in ferromagnetically coupled multilayer films of (Co/NiFe/Co)Cu were investigated using Fresnel imaging. The films possess an in-plane uniaxial anisotropy and both easy and hard axis magnetism reversal were typical of ferromagnetically couple multilayer films. On application of a hard axis field, a splitting of the domain walls into two was observed. No wall transitions occurred but the split wall separation increased with the applied field. The formation of 360 degrees wall loops from small domains was observed on application of a hard axis field and magnetic fields up to 20H(k) were required to annihilate them. The magnetisation reversal on application of a field at an angle of 25 degrees to the hard axis is highly complex and a detailed analysis of the reversal processes has been carried out using power spectra of fresnel images taken during magnetisation reversal.