Microstructure analysis of a SmCo/Fe exchange spring bilayer

The microstructure of a magnetron sputtered Cr(20 nm)/Sm-Co(20 nm)/Fe(20 nm)/Cr(5 nm) exchange spring magnet was studied using an advanced analytical transmission electron microscopy to better understand the relationship between its chemistry and structure to enhance the energy product. It is shown that the Fe atoms diffuse into the well textured Sm-Co layer, causing a transition from the stoichiometric Sm2Co7 near the Sm-Co/Cr interface to a defected Sm(Co,Fe)(5) in the Sm-Co-Fe intermixed area. The graded intermixed layer between Sm-Co and pure Fe gives rise to a compositionally enhanced energy product.