Charge Transport Mechanisms in Single Crystalline Yttrium Iron Garnet as Resolved by Magnetic Relaxations

Single crystalline Yttrium Iron Garnet (YIG) has been irradiated at T ≈︂ 80 K with 3 MeV electrons to a dose of ≥1019 e–cm–2 and the recovery of the induced lattice damages, after systematic annealing over the temperature range 80 K > Ta > 1400 K, is carefully investigated by means of magnetic after-effect (MAE) spectroscopy, covering the range 4 K > T > 500 K. The wide extension of recovery is attributed, besides to Fe3+ and Fe2+ interstitials and their associated d- and a-site vacancies, especially to the larger, and hence less mobile, Y3+ interstitialcies and their c-type vacant sites. The obtained data allow to resolve various charge transport mechanisms: (i) tunneling of electrons in combination with intra-atomic excitations in the low-temperature zone (4 K > T > 55 K); (ii) small-polaron hopping, extended over the range 80 K > T > 350 K; (iii) primarily radiation-induced, Debye-type ionic reorientation processes with peak temperatures near to 250, 325 and 400 K.