Magnetic properties of Fe+-implanted silica films after post-implantation annealing

Abstract

Magnetic properties of Fe-implanted silica films after different annealing processes were studied. The magnetization of the samples annealed at Ta⩽600 °C was very weak, and hard to saturate due to the superparamagnetic effect. At Ta=800 °C, the saturation magnetization increased significantly, but still much lower than that of bulk Fe. The coercivity of the films, either as-implanted or annealed, was much higher than that of bulk Fe. No evident magnetic domain structure can be observed for the as-implanted and 600 °C annealed samples, which implied that the magnetic particles at lower temperatures were small and deeply embedded in the film. During the annealing process at 800 °C, the implanted Fe atoms gradually diffused outward with the formation of islands on the film surface. These islands were demonstrated to be ferromagnetic. At the initial stage of annealing (ta⩽1 h), all the islands were of a single-domain magnetic structure. Besides these islands, some embedded magnetic particles could also be detected. When the annealing time was prolonged to 2 h, double-domain or multidomain magnetic structures could be observed in some larger islands, and no detectable magnetic particles remained in the films.

Fabrication of surface magnetic nanoclusters using low energy ion implantation and electron beam annealing

“…While many studies have been carried out to understand the properties and growth mechanism in chemical synthesis [10], the growth mechanism for ion beam synthesized nanoclusters is still unclear. In previous studies, high dose medium energy ion implantation and conventional oven annealing have been used to synthesize metallic and semiconductor nanoclusters in a dielectric matrix [11][12][13][14].…”

Local structure, optical and magnetic studies of Ni nanostructures embedded in a SiO2matrix by ion implantation

“…Amekura et al [23] have investigated the formation of NiO nanoparticles in SiO 2 from the thermal oxidation of Ni/SiO 2 nanocomposites by using this technique. Ding et al [24] had also shown similar oxidation effects in the case of a Fe implanted SiO 2 matrix. Recently, Lobotka et al [3] have shown the single electron transport phenomenon in the case of isolated Fe nanoparticles in a SiO 2 matrix.…”

Influence of annealing on microstructure and magnetic-transport of FeCo–SiO2 nanogranular films

“…On the one hand, with increasing the annealing temperature, some granules maybe change their structure from amorphous state to crystal state, then leading to the increment of the susceptibility and the saturation magnetization. On the other hand, with lower annealing temperature, there exist a larger number of smaller granules behaving as superparamagnetic which cannot rotate easily to the direction of applied field under the applied field of 1.25 T, thus, resulting in lower susceptibility and lower saturation magnetization under the applied field of 1.25 T [25]. With increasing the annealing temperature, granules grow to be larger ones and there exist a larger number of larger granules which can rotate easily to the direction of applied field of 1.25 T, thus, resulting in higher …”