\textbf{Nanoparticulate CoPt Thin Films}

Equiatomic FePt and CoPt alloys are very attractive for application in high density recording media because of the high magnetocrystalline anisotropy K of their \textbf{fct }(L1$_{\mathrm{0\thinspace }})$ structure with values exceeding 2MJ/m$^{\mathrm{3}}$.The aim of this study is to fabricate a nanoparticulate CoPt film consisting of CoPt nanoparticles embedded in a matrix. To obtain this we have used co-sputtering of CoPt with different materials M$=$ BN,C, Cu and SiO$_{\mathrm{2}}$. Our first experiments were done on CoPt films with thickness of 200 nm. The as-sputtered films had the \textbf{fcc} structure and a coercivity of 150 Oe. Annealing at 700 $^{\mathrm{o}}$C for 30 min led to an increase in coercivity to 4 kOe. Optimization studies are under way to find the optimum sputtering conditions to obtain a fully ordered tetragonal structure with the highest value of coercivity which can then be used in the nanoparticulate composites. Work supported by DOE BES- FG02-04ERU4612