Study of Magnetic Domain Structure in Co(Fe)/Pd Multilayers using Off-axis Electron Holography

Magnetic nanostructures that are magnetized perpendicular to their surface are central to many developing technologies, including spintronics devices and patterned media, because of the requirement to maintain thermal stability as device dimensions are scaled further into the nanoscale. Multilayer or superlattice materials such as Co(Fe)/Pd are convenient for these applications due to their highly tunable perpendicular anisotropy [1]. In this study, Co(Fe)/Pd multilayers with structure: Ta/Pd/[Co(Fe)/Pd] X n/Pd were deposited by dc-magnetron sputtering on thermally oxidized Si wafers. Samples were thinned to electron transparency in cross-section and plan-view geometry. High-resolution images were recorded with a JEM-4000EX HREM at 400keV and a CM-200 at 200keV to reveal crystal structure. STEM images were recorded by JEM-2010 to characterize the multilayer interfaces. The magnetic domain structure was studied by off-axis electron holography using a CM-200 equipped with electrostatic biprism and Lorentz lens. In addition, perpendicular magnetic domain morphology and surface roughness was characterized by AFM/MFM. Here, we correlate crystal structure and magnetic properties.