Effect of interlayer interaction on domain structure of CoPt stacked films with perpendicular anisotropy

Abstract

The effect of interlayer magnetostatic interaction on the domain structure of CoPt (3 nm)/Pt (δPt nm)/CoPt (10 nm) stacked films having perpendicular anisotropy is investigated. The domain structure of the demagnetized CoPt stacked films is observed using magnetic force microscope. The Co80Pt20 stacked films with Pt interlayer thickness δPt less than about 20 nm have the maze domain similar to that of the film with δPt of 0 nm. This is because the top and bottom layers are connected by the magnetostatic interaction and the magnetization distribution of both layers is integrated. The domain structure of the films with δPt around 25 nm is mixture of the maze and irregular domains. For the films with δPt over about 30 nm, because the interaction between the top and bottom layers decreases, the irregular domain which is observed in the 3 nm thick CoPt single layer film appears. In the region where the domain structure changes from the maze domain to the irregular one, domain size steeply increases with increase of δPt.