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Title: The local structure and ferromagnetism in Fe-implanted SrTiO₃ single crystals

We report a connection between the local structure of low-level Fe impurities and vacancies as the cause of ferromagnetic behavior observed in strontium titanate single crystals (STO), which were implanted with Fe and Si ions at different doses then annealed in oxygen. The effects of Fe doping and post-implantation annealing of STO were studied by X-ray Absorption Near Edge Structure (XANES) spectroscopy and Superconducting Quantum Interference Device magnetometry. XANES spectra for Fe and Ti K- and L-edge reveal the changes in the local environment of Fe and Ti following the implantation and annealing steps. The annealing in oxygen atmosphere partially healed implantation damages and changed the oxidation state of the implanted iron from metallic Fe⁰ to Fe²⁺/Fe³⁺ oxide. The STO single crystals were weak ferromagnets prior to implantation. The maximum saturation moment was obtained after our highest implantation dose of 2×10¹⁶ Fe atom/cm², which could be correlated with the metallic Fe⁰ phases in addition to the presence of O/Ti vacancies. After recrystallization annealing, the ferromagnetic response disappears. Iron oxide phases with Fe²⁺ and Fe³⁺ corresponding to this regime were identified and confirmed by calculations using Real Space Multiple Scattering program (FEFF9).
Authors:
;  [1] ;  [2] ; ;  [1] ;  [3]
  1. Department of Physics and Astronomy, The University of Western Ontario, London ON N6A 5B7 (Canada)
  2. Department of Chemistry, The University of Western Ontario, London ON N6A 5B7 (Canada)
  3. (Canada)
Publication Date:
OSTI Identifier:
22306177
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 1; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ABSORPTION SPECTROSCOPY; ANNEALING; FERROMAGNETISM; IMPURITIES; IRON ADDITIONS; IRON OXIDES; MONOCRYSTALS; MULTIPLE SCATTERING; OXYGEN; RECRYSTALLIZATION; SATURATION; SILICON IONS; SPECTRA; SQUID DEVICES; STRONTIUM TITANATES; VACANCIES; X RADIATION; X-RAY SPECTROSCOPY