Improved perpendicular magnetic properties of pulsed-dc-sputtered FePt thin films

Magnetic properties and microstructure of FePt thin films prepared by pulse dc sputtering on SiO2/Si(100) substrates are studied. As comparing to the films prepared by conventional dc sputtering, FePt films fabricated by pulse dc sputtering show higher ordering parameter (S) of 0.6-0.8 at the post annealing temperature (Ta) in the range of 500-700 °C. In addition, a strong (00l) texture with Lotgering orientation factor (LOF) of ~0.96 is obtained at Ta = 700 °C. The enhanced perpendicular magnetic anisotropy at room temperature with sufficient high out-of-plane coercivity of 9 kOe is reached. Microstructure analysis indicate that pulse dc deposition significantly enhances grain growth during post annealing, which explains the higher ordering parameter and infers that the development of (001) texture could be related to the tensile densification strain. Moreover, the films prepared by pulse dc sputtering shows lower onset annealing temperature of 400 °C, which is 100 °C lower than that in the film fabricated by conventional dc sputtering. The results of this study reveal that pulse dc sputtering is an effective method to improve the perpendicular magnetic properties of FePt films and lower post processing temperature, which could be useful for related applications.