Ni1-xfex nanoparticles made by low energy dual ion implantation into SiO2

Abstract

Ni1-xfex nanoparticles were made by implanting Ni and Fe at 10 keV into a SiO2 film and electron beam annealing (EBA) with a Ni:Fe fluence ratio of 44:56. The as-implanted nanoparticles were superparamagnetic with average diameters of∼4 nm. The high field moment followed Bloch's T3/2 law where T is the temperature and there was a spin-glass component from disordered surface spins that was not previously reported for an implanted film with a Ni:Fe fluence ratio of 82:18 made under similar conditions. EBA led to non-spherical near surface Ni1-xFex nanoparticles with widths ranging from∼60 nmto∼220 nmwhere some of the nanoparticles were surrounded by a Fe1-z1Siz1Oz2 shell. Unlike the previous r..