Impact of irradiation-induced point defects on electronically and ionically induced magnetic relaxation mechanisms in titano-magnetites

Abstract

This report deals with the analysis of point-defect-induced magnetic after-effect (MAE) processes occurring in as-grown, single-crystalline titano-magnetite (Fe2.8–DTi0.2O4), containing B-site vacancies (D < 0.005). In a foregoing experiment, these processes, situated near 450 K, 200 K and 65 K, have been completely recovered in the course of systematic annealing up to Ta ≤ 1200 K. Analysis of respective annealing kinetics suggested to associate them with vacancy- (450 K) and interstitial-based (200 K) defect reorientations, including modified electron hopping (65 K). The present study was performed in order to check the previously developed relaxation model by low-temperature (80 K) electron (e–) irradiation of the prerecovered crystal and investigating if thereby the point-defect relaxations of the initial, as-grown, state could be reconstituted. MAE analyses, based on systematic sample annealing in the temperature range 80 K ≤ Ta ≤ 1200 K prove, indeed, radiation-induced reproduction of related processes. Partial modifications of respective process genealogies may be conveniently assigned to the alternative techniques of defect induction, i.e. high-temperature crystal growth in thermal equilibrium or out-of-equilibrium, low-temperature e–-irradiation. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)