Correlation of domain processes and magnetoresistance changes as a function of field and number of bilayers in Co/Cu multilayers

Abstract

The understanding of the magnetization processes in Co/Cu multilayers showing substantial giant magnetoresistance (GMR) is incomplete. To gain further insight into the coupling and resultant switching characteristics, a series of Co/Cu multilayers with 3–15 bilayers has been grown by dc magnetron sputtering. Microstructural and micromagnetic studies along with MR measurements were made on the samples. Lorentz microscopy was used to directly observe the evolution of domain structures under the influence of an applied field. It appeared that dissimilar domain structures occurred in different layers. Magnetic structures were generally submicron in size although in samples with few bilayers well defined domain walls were also observed during the reversal process. Their occurrence coincided with abrupt steps in the GMR curves.