TEM investigation of the magnetisation 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 magnetisation reversal were typical of ferromagnetically coupled 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° wall loops from small domains was observed on application of a hard axis field and magnetic fields up to 20Hk were required to annihilate them. The magnetisation reversal on application of a field at an angle of 25° 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. © 1994.