Plasma-immersed oxygen ion implantation of iron-doped glass for nonmetallic magnetic hard disks

Abstract

The object of this work is to develop a fabrication process to produce a nonmetallic magnetic hard disk with a thin magnetic layer that features small magnetic spinel grains suspended in a host nonmetallic medium. Plasma source ion implantation (PSII) of oxygen into iron-doped magnesium aluminosilicate (MAS) glass and simultaneous implantation of iron and oxygen into calcium aluminosilicate (CAS) glass have been investigated. The implant energy used in these experiments was 30 keV and the oxygen dose was estimated to be 1×1017 ions/cm2 for both MAS and CAS glasses. The results showed that PSII of oxygen into MAS glass increased the iron ions’ binding energy, probably due to the valence state conversion of Fe2+ to Fe3+. The post anneal yielded a thin two-phase layer near the surface, consisting of Mg–Fe–Si–O crystals and the glass matrix. A slight segregation of Fe in the implanted region took place during the anneal, because of the out-diffusion of Fe2+ ions from the substrate to the oxygen-rich region. The simultaneous implantation of iron and oxygen into CAS glass resulted in the formation of an iron oxide, Fe2O3.