(001) FePt nanoparticles with ultrahigh density of 10 T dots/in.2 on amorphous SiO2 substrates

Abstract

Highly ordered single-crystalline (001) FePt nanoparticles (NPs) with controllable sizes and a well-aligned easy axis were obtained by tuning the layer numbers and the SiO2-layer thickness of atomic-scale [Fe/Pt/SiO2]n multilayers deposited on SiO2∥Si substrates. After 700 °C annealing, quasi-self-assembled NPs with ultrahigh areal density of 1.0×1013 dots/in.2 and large out-of-plane coercivity (Hc,⊥) of 31 kOe were achieved. All particles were embedded into the SiO2 substrates due to the low surface energy of SiO2, which significantly prevented the coarsening during annealing and resulted in a reduced particle size of 5.6 nm and small size distribution of 14.1%.