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Ordering and Grain Growth Kinetics in CoPt Thin Films

  • R. A. Ristau (a1), K. Barmak (a1), D. W. Hess (a2), K. R. Coffey (a3), M. A. Parker (a3) and J. K. Howard (a3)...


Ordering and grain growth have been studied in a 10 nm thick CoPt alloy film of equiatomic composition annealed in the temperature range 550–700°C by quantifying ordered domain size, volume fraction ordered, grain size, and grain size distribution. Ordering occurs by nucleation and growth of Ll0 ordered domains, with a mean size of 3 nm at 550°C and 19 nm at 700°C. The volume percent ordered shows a dramatic increase from <y1% to approximately 28% between the two extremes of annealing temperature. The mean grain size of the as-deposited films is 5 nm and the entire film is face-centered cubic. Upon annealing in the temperature range 550–600°C, the mean grain size reaches a stagnation limit of 27 nm and the grain size distribution is log-normal. Grain growth resumes beyond 600°C and the mean grain size reaches as high as 55 nm at 700°C. The increase in the coercivity of the annealed films follows the increase in the ordered fraction more closely than the increase in grain size. The shape of the M-H loop shows evidence of coupling between the magnetically hard (ordered) and soft (disordered) regions.



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