  Pt(x{\AA})/Co(5{\AA})/Pt(10{\AA}) trilayer films were deposited on naturally
oxidized Si(111) substrate to investigate Ti underlayer effect on PMA. A small
amount of Ti underlayer promoted the magnetic anisotropy to a perpendicular
direction for x=8{\AA} and 10{\AA}. Both GI XRD and STM results showed that the
Ti underlayer manipulated the growth of trilayer film. The Pt particles
preferably grow the neighborhood of the Ti cluster, giving rise to a relatively
smooth layer with a fiber texture fcc (111) structure. By contrast, the absence
of Ti underlayer leads to clustered, relatively rough, and randomly oriented
nano-crystalline growth. Differences in the growth mode, especially roughness,
also appeared as intensity loss in XPS spectra due to shadowing effects. Our
results indicate that a traceable amount of underlayer can change the magnetic
anisotropy of the film by manipulating film growth.
