MODIFICATION OF THE PERPENDICULAR MAGNETIC ANISOTROPY OF ULTRA-THIN CO FILMS DUE TO THE PRESENCE OF OVERLAYERS

초록

In order to understand the effect of interfacial strain on perpendicular magnetic anisotropy (PMA) of ultra-thin Co films, ex situ Brillouin light scattering measurements were performed for differnt overlayer materials. The samples were prepared by molecular beam epitaxy and Cu, Al and Au were used as overlayer materials. We observed a decrease in PMA with the Cu and Al overlayers, and will present our measurements of the uniaxial anisotropies of the films as a function of Au underlayer thickness. In addition, we found an unexpected result that the PMA is significantly reduced when an Au overlayer of 3.5 nm is covered by an extra Al capping layer. The amount of this reduction depends on the thickness of the Al layer. Our results lead us to speculate that misfit strain at the interface between the Al and the Au can be propagated through the Au layer to affect the magnetic properties of Co.