Preannealing effect on ordering transformation and magnetic properties of CoPt thin films.

Single layer CoPt thin films with thicknesses from 30 to 100 nm were sputtered on glass substrates. A preannealing at 250 °C for 80 min was applied to the samples, before ordering treatment at 700 °C for 10 min. This preannealing process resulted in a 33%–65% decrease in coercivity and 23%–55% decrease in volume fraction of order phase f₀. Results of morphology investigation showed that the preannealing increases the surface roughness, which mainly results from the elimination of defects. Structural results further suggest that the eliminated defects are mostly low dimensional, such as dislocations or vacancies. It can thus be concluded that those low dimensional imperfections in the CoPt films play an enhancing role in ordering transformation process. [ABSTRACT FROM AUTHOR]