The perpendicular magnetic anisotropy(PMA) was shown to be established in ferromagnetic (FM)/fcc-Mn bilayers through the FM-antiferromagnetic (AFM) exchange coupling. We demonstrate here that such PMA can be further enhanced by incorporating an ultrathin Fe film as an underlayer. In a series of Fe/Mn bilayers, hysteresis loop measurement shows that the thickness of top Fe layer with PMA can be extended to a thicker range while an ultrathin Fe underlayer is inserted. Such enhancement of PMA is attributed to an increase of AFM ordering on the Mn film originated from the magnetic proximity effect with the Fe underlayer.

Spin transfer switching characteristics in a [Pd/Co]m/Cu/[Co/Pd]n pseudo spin-valve nanopillar with perpendicular anisotropy

The study systematically investigates the morphology, element composition, and magnetic properties of Co and Fe films on faceted Pd/W{112} upon thermal annealing. Co thin films aggregate and form 3-dimensional islands at 400–450 K, while the {112} facets are still sustained after further annealing to 900 K. Fe thin films aggregate and form 3-dimensional islands at a lower temperature, 300–350 K, and there is no observable faceted structure after annealing at 300–900 K. The Co and Fe films on Pd/W{112} reveal stable in-plane magnetism at 100 K. The magnetic coercivity (Hc) of Co and Fe films increases and decreases, respectively, when increasing the thickness. The Hc of Co films are significantly enhanced by 2–4 times after annealing at 400–450 K, but the Hc of Fe films remain invariant upon thermal annealing at 400–450 K. These comparative studies of Co and Fe films on faceted Pd/W{112} clearly reveal the significant differences between the two systems and provide valuable information for future applications.