Energy product enhancement in Fe49-xCoxPt51 thin films

In this paper, energy product (BH)_max enhancement in Fe_49-xCo_xPt₅₁ thin films is investigated. The thin films are fabricated by rf magnetron sputtering and later are annealed at temperature range of 400-700°C. Crystal structure is identified by X-ray diffraction and results indicate that the ordering transformation is extensively observed as the FePt sample is annealed at 400°C. Addition of cobalt is harmful for the formation of the L1₀ ordered structure because the starting temperature for ordering transformation is increased. H_c values for FePt and FeCoPt thin films are increased with annealing temperature while the M_r is decreased. The (BH)_max of cobalt-containing thin films is found to be much larger than that of the binary samples. The enhanced (BH)_max of the cobalt alloyed films is mainly obtained by improving the coercive squareness ratio (S*) and M_r. The optimum degree of ordering transformation and smaller particle size are found to contribute in the enhanced magnetic properties of the FeCoPt thin films.