Giant magnetoresistance in electrodeposited Co-Cu/Cu multilayers: Origin of the absence of oscillatory behavior

摘要: A detailed study of the evolution magnetoresistance was performed on electrodeposited Co/Cu multilayers with Cu-layer thicknesses ranging from 0.5 to 4.5 nm. For thin Cu layers (up 1.5 nm), anisotropic (AMR) observed, whereas thicker exhibited clear giant (GMR) behavior. The GMR magnitude increased up about 3.5--4 nm thickness and slightly decreased afterward. According magnetic measurements, all samples ferromagnetic (FM) relative remanence turned out be 0.75 for both AMR- GMR-type multilayers. This clearly indicates absence an antiferromagnetic (AF) coupling between adjacent even above where effect occurs. AMR behavior at low spacer presence strong FM (due to, e.g., pinholes in and/or areas layer is very small). With increasing thickness, pinhole density reduces uniformity improves, which lead a weakening coupling. improvement multilayer structure quality results better separation weaker (or complete interlayer coupling) enables more random magnetization orientation layers, this leading increase GMR. Coercive field zero-field resistivity measurements as well structural reported earlier same provide independent evidence microstructural features established here. critical analysis former suggests oscillating these systems. It pointed that large previously such around 1 can attributed fairly superparamagnetic (SPM) fraction rather than being due AF In SPM regions present study, only occurs dominating