Assembly of FePt L1₀ nanoparticles grown on MgO(110) with self-organized groove structure

We have fabricated an FePt nanoparticle assembly on a MgO(110) with a self-organized structure. Prior to FePt deposition, the MgO(110) substrate was annealed at 1273 K in air to develop self-organized grooves running along the [11̄0] direction with average periodicity of 14.5 nm. Subsequently a very thin FePt layer with nominal thickness of 1.5 nm was sputtered onto the MgO substrate at 973 K, resulting in FePt L1₀ nanoparticles with 2-4 nm in diameter aligned along the grooves. Each FePt nanoparticle was a L1 ₀ single crystal with its c-axis tilting 45° or -45° from the substrate normal that corresponds to MgO[100] or [010], The magnetic properties of the FePt nanoparticle assembly well reflected such c-axis distribution, and their switching behavior almost followed the Stoner-Wohlfarth model.