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Title: Spontaneous formation of suboxidic coordination around Co in ferromagnetic rutile Ti{sub 0.95}Co{sub 0.05}O{sub 2} film

To evaluate local atomic structures around Co in high temperature diluted ferromagnetic semiconductor Co-doped TiO{sub 2}, x-ray fluorescence holography and x-ray absorption fine structure experiments were carried out on rutile paramagnetic Ti{sub 0.99}Co{sub 0.01}O{sub 2} and ferromagnetic Ti{sub 0.95}Co{sub 0.05}O{sub 2} films. The Co atoms in the Ti{sub 0.99}Co{sub 0.01}O{sub 2} simply substituted for Ti sites in the rutile structure, whereas a suboxidic arrangement of CoO{sub 2}Ti{sub 4} formed around Co in the Ti{sub 0.95}Co{sub 0.05}O{sub 2} films. A theoretical investigation based on a series of first-principles calculations indicated the stability of the aggregated suboxidic clusters in the rutile TiO{sub 2}, supporting our hypothesis for the formation of suboxidic coordination in the highly Co-doped sample. The suboxidic coordination may be the source of strong exchange interaction, resulting in the high Curie temperature in Co-doped TiO{sub 2}.
Authors:
 [1] ;  [2] ;  [3] ; ;  [4] ;  [5] ;  [6] ; ;  [7] ;  [8] ;  [9]
  1. National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973 (United States)
  2. Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)
  3. Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan)
  4. Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)
  5. School of Information Sciences, Hiroshima City University, Hiroshima 731-3194 (Japan)
  6. Department of Physics, Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan)
  7. Japan Atomic Energy Agency, Hyogo 679-5148 (Japan)
  8. JASRI/SPring-8, Hyogo 679-5198 (Japan)
  9. Quantum Phase Electronics Center and Department of Applied Physics, The University of Tokyo, Tokyo 113-8656 (Japan)
Publication Date:
OSTI Identifier:
22415102
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 22; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; COBALT; COBALT OXIDES; CURIE POINT; DOPED MATERIALS; FERROMAGNETIC MATERIALS; FILMS; FINE STRUCTURE; PARAMAGNETISM; RUTILE; TITANIUM OXIDES; X-RAY FLUORESCENCE ANALYSIS