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Title: Rise and fall of ferromagnetism in O-irradiated Al{sub 2}O{sub 3} single crystals

In dilute magnetic semiconductors studies, sapphire was usually used as non-magnetic substrate for films. We observed weak ferromagnetic component in Al{sub 2}O{sub 3} single crystal substrate, and excluded the possibility of ferromagnetic contaminations carefully by inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy. The ferromagnetism rise and fall during the process of annealing-oxygen irradiation-annealing of the sapphire. The ferromagnetic changes are consistent with Al-vacancy related defects detected by positron annihilation spectroscopy. With first-principle calculations, we confirm that Al-vacancy can introduce magnetic moment for 3 μB in Al{sub 2}O{sub 3} crystal and form stable V{sub Al}-V{sub Al} ferromagnetic coupling at room temperature.
Authors:
 [1] ;  [2] ; ; ; ;  [1]
  1. State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei 230026 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22490708
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 23; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALUMINIUM OXIDES; ANNEALING; ANNIHILATION; CONTAMINATION; COUPLING; DEFECTS; FERROMAGNETISM; FILMS; ICP MASS SPECTROSCOPY; IRRADIATION; MAGNETIC MOMENTS; MAGNETIC SEMICONDUCTORS; MONOCRYSTALS; OXYGEN; POSITRONS; SAPPHIRE; SUBSTRATES; TEMPERATURE RANGE 0273-0400 K; X-RAY PHOTOELECTRON SPECTROSCOPY