Improvement in perpendicular magnetic anisotropy and its voltage control efficiency in CoFeB/MgO tunnel junctions with Ta/Mo layered adhesion structures.

By utilizing Ta/Mo layered adhesion structures, thermally robust perpendicular magnetic anisotropy and voltage-controlled magnetic anisotropy (VCMA) effects were achieved in magnetic tunnel junctions (MTJs) with ultrathin CoFeB films grown on MgO. After annealing at 400 °C, MTJs with Ta/Mo layered adhesion exhibited VCMA coefficients of 48 fJ/Vm. The combination of Ta and Mo improved the crystalline orientation and flatness of the CoFeB/MgO tunneling barrier interfaces, as determined by cross-sectional scanning transmission electron microscopy. Additionally, we demonstrate that the small interdiffusion between Mo and CoFe enables effective scavenging of B from CoFeB by increasing the thickness of the B sink layer without impairing the device performance due to atomic diffusion. [ABSTRACT FROM AUTHOR]