Perpendicular magnetic anisotropy of epitaxially grown L1 ₀-FePdCu nanoparticles with preferential c -axis orientation

Oriented and well-isolated 14-nm -sized Fe41 Pd52 Cu7 ternary alloy nanoparticles with the L 10 -type ordered structure have been fabricated by the sequential deposition of Pd, Cu, and Fe on NaCl (001) substrate followed by postdeposition annealing. The annealing temperature required to obtain a high coercivity decreased by at least 50 K upon the addition of a small amount of Cu. Furthermore, it was revealed that a strong preferential c -axis orientation along the film normal direction was achieved by the addition of Cu, which resulted in a strong perpendicular magnetic anisotropy. The population of the nanoparticles with their c -axis oriented normal to the film plane was 74%. The alloy composition was independent of the particle size, as determined by energy dispersive x-ray spectroscopy using nanoprobe electrons. Nanobeam electron diffraction revealed that the axial ratio is constant for FePdCu nanoparticles with sizes between 10 and 25 nm. Interparticle magnetostatic and exchange interactions played an insignificant role in the isolated FePdCu nanoparticles. The correlation between their preferential c -axis orientation and magnetic properties is discussed based on the rotation magnetization of single magnetic domain particles.