High-energy xenon ion irradiation effects on the electrical properties of yttrium iron garnet

Thin monocrystalline samples of yttrium iron garnet (YIG) were irradiated at room temperature with 27 MeV/A 132Xe ions at varying fluences. The sample thickness (100 μm) was smaller than the mean projected range of ions (170 μm) so that we were able to study the effects of radiation damage alone. At such a high ion energy damage is mainly due to electronic excitation energy loss. Transverse two probe-d.c resistivities of the irradiated samples were measured at room temperature as well as the real (ε'r) and imaginary part (εr) of the dielectric constant up to 10 MHz. The YIG d.c conductivity is found to rise by a factor 40 for the highest dose while the permittivity (ε'sb(r)) increased only slightly after irradiation (40% max). The dielectric losses are also enhanced as the ion fluence increases especially at lower frequencies (by a factor 6 at 10 KHz). These preliminary results are discussed bearing in mind that latent tracks are produced in the samples. The experimental data are plotted as a function of the volume fraction of the disordered track cores (fp) which serves as a measure of the damage rate. The variations of d.c conductivity and dielectric losses with fp are unexpectedly non-linear and are not understood at present. (author)