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Title: Origin of ferromagnetism in aluminum-doped TiO{sub 2} thin films: Theory and experiments

In this paper, we combine first-principles calculations and experiments to investigate the magnetic properties of aluminum-doped TiO{sub 2} films of rutile structure. Density-functional theory with generalized gradient approximation based calculations were carried out for three cases, where the TiO{sub 2} lattice contains oxygen vacancies V{sub O} only, an oxygen is substituted by a fluorine atom, or a Ti is substituted by an aluminum. Magnetic moments associated with the formation of Ti{sup 3+} ions are found in all cases but they couple differently resulting in different magnetic states. Al-doped samples prepared in our labs exhibit ferromagnetism at room temperature with a T{sub C} near 340‚ÄČK. The experimental results are consistent with the first principles calculations, and the magnetism is associated with the V{sub O} defect electrons induced by the Al doping. The defect electron occupies nearby Ti sites giving rise to the Ti{sup 3+} moments and, at the same time, has spatially extended wavefunctions assuring overlapping between neighbors.
Authors:
; ; ;  [1] ; ; ;  [2] ;  [3] ; ; ;  [4]
  1. Department of Physics, Harbin Institute of Technology, Harbin 150001 (China)
  2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)
  3. Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071 (United States)
  4. Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150001 (China)
Publication Date:
OSTI Identifier:
22395614
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 26; Other Information: (c) 2014 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; ALUMINIUM; APPROXIMATIONS; ATOMS; DENSITY FUNCTIONAL METHOD; DOPED MATERIALS; ELECTRONS; FERROMAGNETISM; FLUORINE; MAGNETIC MOMENTS; MAGNETIC PROPERTIES; OXYGEN; RUTILE; TEMPERATURE RANGE 0273-0400 K; THIN FILMS; TITANIUM IONS; TITANIUM OXIDES; VACANCIES