Grain growth in Co27Pt73 alloy films with perpendicular magnetic anisotropy

The grain size of Co27Pt73 alloy films as-deposited and annealed at 250 deg reesC has been studied by transmission electron microscopy (TEM) and x-ray diffraction. The grain size was found to increase from 4-8 to 20-35 nm when the thickness of the films changed from 7 to 49 nm, while the magnetic ani sotropy constants of the films increased from 0.048 to 0.28 MJ/m3. The grai n size increase was found to be independent of the growth time, but depende nt on the film thickness. Significant stress in the Co27Pt73 alloy films wa s revealed by the difference between the grain sizes determined by the Sche rrer equation and TEM. Evidence and analysis indicate that the local anisot ropy structure resulting in perpendicular magnetic anisotropy in CoxPt1-x ( x approximate to 0.25) alloy films may be stable at 250 degreesC. (C) 2001 American Institute of Physics.