Abstract
Well-aligned (001)-oriented granular or particulate L 10 FePt films on amorphous Si O2 or glass substrates were obtained by depositing atomic-scale FePtSi O2 multilayers followed by various postannealing conditions. After 350 °C annealing, (001) FePt-Si O2 granular films were obtained with an average grain size of 5.14 nm, perpendicular coercivity of 7.7 kOe, and squareness of 0.95. The diffusion of Si O2 to grain boundaries and free surface of FePt accelerated the diffusion of Fe and Pt atoms to form the L 10 phase; therefore, low-temperature ordering of FePt was achieved. By further raising the annealing temperature to 700 °C, isolated particles of aligned (001) single crystals were achieved. The nucleation of voids occurred at low temperatures due to the existence of low-surface-energy Si O2, and then an agglomeration process proceeded, leading to a particulate structure. The isolated particles showed a perpendicular coercivity of 60 kOe and squareness of unity. © 2008 American Institute of Physics.