Damage and conductivity of yttrium iron garnet irradiated with GeV-heavy ions

Single crystals of Si-doped yttrium iron garnet (YIG : Si) have been irradiated with 6 GeV 208Pb ions at 80 K and 300 K. The amorphization cross section, for a mean electronic stopping power of 35 MeV μm-1, was determined from the 300 K 57Fe Moessbauer spectra. When going from the crystalline to the amorphous phase, the 300 K dc conductivity was found to decrease versus fluence. This is interpreted by the lowering of the carrier mobility caused by disorder. Furthermore, the 300 K ac conductivity of amorphous YIG : Si exhibited above 10 kHz an ωα law, with α similar eq0.8, characteristic of hopping conduction. These results are discussed with respect to undoped YIG irradiated with GeV heavy ions. No significant effects neither of the irradiation temperature, nor of the electrical conductivity are observed on the damage cross section. ((orig.))