STRUCTURAL MODIFICATIONS OF YTTRIUM-IRON-GARNET AFTER HIGH-ENERGY HEAVY-ION IRRADIATIONS

Irradiation of thin epilayers of yttrium iron garnet (YIG) was performed at room temperature with 50 MeV S-32, 50 MeV Cu-63 and 235 MeV Kr-83 ions, for which the energy loss in the targets was mainly due to electronic excitation and ionization. The resulting damage was studied by high-resolution X-ray diffraction (HRXRD) and transmission electron microscopy (HRTEM). In the case of Kr irradiation, both HRXRD and HRTEM showed that YIG was progressively amorphized by the increasing track overlap, while in the case of S and Cu irradiations, HRTEM showed that some recrystallization of the amorphous tracks occurred, leading to grain sizes around 10 nm. It is concluded that these processes are triggered by the electronic energy loss. Previous resistivity and saturation magnetization measurements are discussed with respect lo the present structural data.