Direct observation of domains and magnetization switching processes in NiFe/alumina/Co trilayer junctions

Abstract Transmission Lorentz microscopy was used to observe the effect of an applied field on the domain structure and magnetization process of NiFe/alumina/Co junctions. The alumina layer was prepared either by oxidizing a sputtered Al layer in air, or by direct sputtering of Al 2 O 3 . Two distinct magnetization reversal processes, where NiFe reverses first, followed by the magnetization reversal of Co, were observed with increasing applied field. The range of field values over which the magnetization of NiFe and Co are in an antiparallel configuration is approximately the same for both films. The alumina thickness, and waviness of the interfaces, can affect the magnetization process of the junctions.