We use a new method for visualization and direct experimental study of
dynamic magnetization processes and for nondestructive characterizati
on of the defect structure of magnetic multilayers. The method utilize
s a transparent indicator ferrimagnetic magneto-optic film with in-pla
ne anisotropy. An example of its application to the investigation of t
he magnetization reversal by domain wall motion in electrochemically p
roduced CoNiCu/Cu multilayers which exhibit a giant magnetoresistance
effect is described.