Magneto-optical properties for antiferromagnetically coupled CoPt stacked films with hexagonal anti-dot lattices

Abstract

The influence of two-dimensional array structures (hexagonal anti-dot lattices) on magneto-optical (MO) properties was investigated in perpendicular antiferromagnetically coupled Co80Pt20 stacked films containing ZnO optical interference layers. Antiferromagnetic exchange coupling was generated in a [CoPt/Ru/CoPt] tri-layered structure, and anti-dot lattices were formed on both CoPt layers. The exchange coupling between the CoPt layers across a very thin 0.46-nm Ru interlayer was maintained even after nanofabrication. Characteristic MO hysteresis loops were measured by a 405-nm wavelength incident light on samples containing a 50-nm ZnO optical interference layer. The anti-dot lattice with a 200-nm diameter hole exhibited an increase in the residual Kerr rotation angle owing to the antiparallel magnetization alignment of the CoPt layers. Furthermore, compared with samples without the interference layer, the figure of merit for the anti-dot lattice with a 200-nm diameter hole was enhanced by inserting a 100-nm ZnO interference layer. These improvements are attributed to MO interference effects inside the stacked films.