Pronounced relaxation peaks which occurred in the magnetic after-effect spectra of low-temperature electron-irradiated monocrystalline magnetite were analyzed and were attributed to anisotropic point defect configurations. Cation interstitials and octahedral vacancies were found to be the basic defects. Each of them was present in 2 closely related configurations and gave rise to reorientation-type double peaks at 230K (interstitials) or 300K (vacancies). The analysis of these relaxations yielded reorientation (migration) enthalpies of 0.69 and 0.73eV for the interstitials and of 0.86 and 0.93eV for the vacancies. The role of radiation damage in relaxation mechanisms below the Verwey temperature of 125K, such as tunnelling (4 to 35K) and hopping (45 to 125K) of electrons, was considered. A consistent recovery model was developed which comprised all types of radiation-induced lattice defects.

F.Walz, H.Kronmüller: Physica Status Solidi B, 1994, 181[2], 485-98