Fully Epitaxial, Exchange Coupled SmCo₅/Fe Multilayers With Energy Densities above 400 kJ/m³

Exchange coupled hard/soft magnetic nanocomposites have long been in the interest of research for improving the energy density of the currently best hard magnetic materials such as Nd2Fe14B (512 kJ/m3) or SmCo5(230 kJ/m3). However, to compete with the energy density of a well textured single phase bulk magnet, the hard magnetic phase within the two-phase material should be sufficiently textured as well. Thus, only recently values of more than 300 kJ/m3, i.e., significantly above the theoretical hard phase limit of SmCo5, have been realized in fully epitaxial SmCo5/Fe/SmCo5trilayers. Here we extend our work to fully epitaxial SmCo5/Fe multilayers with reduced individual layer thicknesses of Fe and SmCo5. The rigid coupling of a large volume fraction of high moment soft phase to a hard magnetic Sm-Co phase leads to energy densities above 400 kJ/m3. Phase formation, epitaxial texture and magnetic properties are discussed for a series of multilayers of constant total thickness with respect to the number of introduced interfaces.