Effect of buffer and interlayer on the adhesion and magnetic properties of anisotropic Nd–Fe–B single and multilayer films

Abstract Nd–Fe–B films with good perpendicular magnetic anisotropy were obtained by using a Mo film with the thickness of about 40 nm as buffer layer. Large out-of-plane coercivity ( H c⊥  = 1182 kA/m) and remanent ratio (remanent magnetization/saturation magnetization) ⊥  = 0.99 are obtained by the stratification of the Nd–Fe–B magnetic film in three NdFeB(180 nm)/Mo(5 nm) bilayer sequences using Mo as interlayer. Using a Ni film, with a thickness of about 8 nm, alongside with a Mo film of 40 nm as buffer layer improves the adhesion to substrate and keeps the anisotropic hard magnetic performances of the Nd–Fe–B films unchanged. By increasing the total thickness of the Nd–Fe–B magnetic layer from 540 nm to 1620 nm the coercivity measured at high fields increases from about 1350 kA/m for Nd–Fe–B film with 3 NdFeB(180 nm)/Mo(5 nm) sequences to about 1640 kA/m for Nd–Fe–B film with 9 NdFeB(180 nm)/Mo(5 nm) sequences which can be ascribed to a stronger pinning effect as a result of the increased number of NdFeB/Mo interfaces.