Modeling of Intermediate Behavior in Co/Pt Vertical Magnetization Multilayers
Lawrence H. Bennett, Edward Della Torre, R A. Fry
MOKE hystersis loops were acquired at various radial positions on a 25 mm diameter disk of a (0.3 nm Co/1.2 nm Pt)15 multilayer. At the center of the disk, the loop exhibited bimodal features. At the outer edge, the reversal behavior was significantly altered, and the loop was unimodal. The radial variations in the MOKE loops are attributed to diffusion and interface effects arising from the heating cycles used in the film deposition process. The overall behavior is modeled by assujming that in the intermediate region there is a fraction of bimodal and a fraction of unimodal, and an interaction term between them. One possibility suggested by the model is that the bimodal is characterized by columns of CoPt3 and of Pt threading the multilayers, strongly coupling them, and fully polarizing the Pt layers. Then this thread is lost due to the different growth conditions at the edge of the disk, decoupling and depolarizing the Pt layers.