Magnetic hardening mechanism study in FePt thin films

Fe100-xPtx alloy thin films with x = 25-67 at. % were prepared by dc magnetron sputtering on naturally oxidized Si substrates. Effects of film composition, annealing temperature (300-650 degrees C), annealing time (5-120 min), and cooling rate (furnace cooling or ice water quench cooling) on the magnetic properties were investigated. Optimum conditions for saturation magnetization and coercivity of the Fe100-xPtx alloy films were found with x = 50 at.%, annealed at 600 degrees C for 30 min and cooled by ice water quenching. Our experimental data suggests that the magnetic hardening in Fe100-xPtx alloy thin films is mainly due to the fct gamma(1)-FePt phase and the domain wall pinning effect. The domain nucleation mechanism is dominated in samples with furnace cooling; the domain wall pinning mechanism dominates in samples cooled with ice water quenching. (C) 1999 American Institute of Physics. [S0021-8979(99)60108-6].