Buffer layer effect on magnetic domain structure and coercivity in epitaxial Co/Pt multilayers

Multilayers of Co/Pt on different buffer layers have been made using molecular beam epitaxy. Observation of magnetic domains on Co/Pt multilayers indicates that the size of domains as well as their growth strongly depend on the buffer layers. The layer structures used in this study are Al₂O₃(11-20)/y/[Co(0.3 nm)/Pt(1 nm)] × 30, where y represents Mo(20 nm), Mo(20 nm)/Pt(20 nm), and Pt(20 nm). The growth of domains all show wall motion dominate behavior. Domain displacement of samples with a Mo buffer layer appeared to grow along the crystalline orientation. The film with no buffer layer showed the most irregular boundary domains compared to other films. The average domain width was between 1.56 and 0.80 μm. In addition, we have found that the coercivity of Co/Pt film was enhanced particularly by using a Mo/Pt buffer layer.