Microstructures and perpendicular magnetic properties of Co/Pd multilayers on various metal/MgO seed-layers

Abstract

We studied the effects of metal/MgO seeds (metal = Ta, Ru, or Pd) on the crystalline structure and perpendicular magnetic properties of Co/Pd multilayers to investigate the possibility of developing a (100) texture with sufficiently high perpendicular anisotropy and small switching field distributions for applications such as patterned media and perpendicular magnetic random access memories. The Pd/MgO or the MgO seed successfully promoted a (100) texture of Co/Pd multilayers. In particular, the Pd/MgO seed developed a strong (100) texture in the Co/Pd multilayer and resulted in perpendicular magnetic anisotropies ∼2 × 106 erg/cm3. On the other hand, the Co/Pd multilayer with the Ta/MgO or the Ru/MgO seed showed a strong (111) texture, inducing a perpendicular magnetic anisotropy higher than that of the (100) textured films. The coercive fields of Co/Pd multilayers with the (111) texture were over 4 kOe and higher than those with the (100) texture, which were ∼2 kOe when they were patterned into 2 × 2 μm2 islands. The switching field distributions of the Co/Pd multilayers with the (100) texture were smaller than those of the Co/Pd multilayers with the (111) texture. Our findings suggest that the Pd/MgO or the MgO seed can be a template suitable for device applications.