Giant coercivity nanodots and fractals in CoPt films grown on (001) SrTiO3 using pulsed laser deposition.

High coercivity nanoscale structures of CoPt are grown on (001) SiTiO₃ with pulsed laser ablation. At low growth rate (≃0.4 Å/s), the film morphology changes from a self-similar fractal to nanodots as the deposition temperature is raised from 700 to 800 °C. While the nanodots are L1₀ ordered phase with out-of-plane c axis and coercivity H_c⊥≃30 kOe, the fractals have a nonzero, in-plane c-axis component of the L1₀ phase. The large lattice mismatch between (001) SrTiO₃ and the ac/bc plane of L1₀ imparts tensile strain to the films whose morphological manifestations can be suppressed at high growth rates. [ABSTRACT FROM AUTHOR]