Impact of GdOx insertion on magnetic anisotropy and damping in double-barrier magnetic stacks

For the realization of high-performance spintronic devices, the development of novel magnetic materials/structures satisfying both large perpendicular magnetic anisotropy (PMA) and ultra-low Gilbert damping is strongly desired. Here, we show that the insertion of an ultrathin GdOx layer as a capping in double-barrier ultrathin magnetic stacks provides such a solution. The inserted GdOx capping layer prevents unintended intermixing among the magnetic layer (CoFeB) and oxide layers (MgO and MgFeO), suppressing the deterioration of both the PMA and the Gilbert damping. Remarkably, the variation in the effective oxygen doping rate of the GdOx layer strongly influences both the PMA and the Gilbert damping, likely affected by a change in the polarization of the orbital magnetic moment. As a result, the GdOx inserted stacks present considerable effective PMA values (a maximum of ∼0.55 erg/cm2) while simultaneously maintaining an ultra-low Gilbert damping (a minimum of ∼1.68 × 10−3) within the range of 1.0–1.5 nm CoFeB thicknesses. These results pave the way to realize practical spintronic devices by providing reliable magnetic structures for efficient spin manipulation.