Magnetic Properties of Ions Implanted in Glass; Fe in SiO2

Abstract

ABSTRACTSilica glass platelets have been implanted with Fe(+) ions, 125 KeV and 10⋀-5 A to doses of 10⋀14 cm⋀-2, 10⋀15 cm⋀-2, 10⋀16 cm⋀-2 and 5 x 10⋀16 cm⋀-2. Ion scattering measurements show that the peak of the Fe ion distribution is ~95 nm below the sample surface, approximately Gaussian, with a width at half maximum amplitude of 100 nm. The intensity of a component in the EPR spectra of implanted samples with a width of 300 gauss and an approximately isotropic shape increases with increasing dose. The increase, proportional to dose for doses <⋀16 cm⋀-2, is larger for doses ≥10⋀16 cm⋀-2. In addition for doses ≥10⋀16 cm⋀-2, the component is orientation dependent. Subsequent heat treatments in air at 700° and 800° C alter the shape, intensity, and orientation dependence of the component. The spectral component in as-implanted samples is attributed to paramagnetic states of Fe ions. The threshold for magnetic exchange interactions and consequently long range magnetic ordering at ~300K occurs at a dose ≥10⋀16 cm⋀-2. Data on effects of thermal treatments on intensities and shapes are interpreted in terms of changing chemical composition of precipitating-particles.