Well-aligned (001)-oriented granular or particulate L10 FePt films on amorphous SiO2 or glass substrates were obtained by depositing atomic-scale Fe∕Pt∕SiO2 multilayers followed by various postannealing conditions. After 350°C annealing, (001) FePt–SiO2 granular films were obtained with an average grain size of 5.14nm, perpendicular coercivity of 7.7kOe, and squareness of 0.95. The diffusion of SiO2 to grain boundaries and free surface of FePt accelerated the diffusion of Fe and Pt atoms to form the L10 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 SiO2, and then an agglomeration process proceeded, leading to a particulate structure. The isolated particles showed a perpendicular coercivity of 60kOe and squareness of unity.