Magnetic properties and structural changes in Co$_{50}$Pt$_{50}$ and Co$_{50}$Pt$_{50-x}$Pd$_x$ solid solutions films

We studied the thin films of Co$_{50}$Pt$_{50}$ and Co$_{50}$Pt$_{50-x}$Pd$_x$ with thicknesses between 20 and 1000 Å. Thinner films after annealing showed formation of tetragonal ordered crystallites in their fcc lattice, which are oriented so that the easy magnetization axis is perpendicular to the film plane. The coercivity depends on the thickness of film. These properties are discussed with respect to the annealing treatment and long-range order degree of the films.