Magnetization reversal in narrow strips of NiFe thin films

The magnetization reversal in 2-30μm wide 60nm thick NiFe strips takes place basically by the same process in single layers and closely coupled bilayers as shown by Lorentz microscopy. At remnance after saturation very narrow domains of reverse magnetization exist along the long edges and closure domains are formed at the ends. Under application of a reversing field the center of the strip is sectioned into transverse domains by rotation with opposite sense of adjoining blocks. In single layers with low coercivity [H
c
] the formation of charged walls is thought to retard switching, while in high H
c
films reversal takes place by sweep of the closure domains from the ends through the strip. Closely coupled bilayers enhance rotation of blocks and the movement across the strip of the reverse domains from the long edges.