Nuclear tracks in iron garnet films

Epitaxial iron garnet films of composition ${\mathrm{Y}}_3$ ${\mathrm{Fe}}_5$ ${\mathrm{O}}_{12}$, ${\mathrm{Gd}}_3$ ${\mathrm{Fe}}_5$ ${\mathrm{O}}_{12}$, and ${\mathrm{}(\mathrm{G}\mathrm{d},\mathrm{B}\mathrm{i})\mathrm{}}_3$ ${\mathrm{}(\mathrm{F}\mathrm{e},\mathrm{G}\mathrm{a})\mathrm{}}_5$ ${\mathrm{O}}_{12}$, irradiated with xenon or uranium ions of energies 1.4 and 6 MeV per nucleon exhibit nuclear tracks of lengths between 10 and 30 μm. These tracks were studied by saturation magnetization measurements and conversion electron Mössbauer spectroscopy elucidating a strong crystallographic disorder and a paramagnetic behavior in the track volume. The track diameter depends on mass and energy of the ions used for irradiation and was found to range between 15 and 20 nm for the energies investigated.