Role of oxygen vacancies in tuning magnetic properties of Co-doped SnO{sub 2} insulating films
- Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)
A series of films deposited under different oxygen partial pressures and annealed under different atmospheres were prepared to investigate the role of oxygen vacancies in tuning magnetic properties of Co-doped SnO{sub 2} films. The inclusive Co in SnO{sub 2} is in the 2+ state and substitutes for the Sn{sup 4+} site. Intrinsic room temperature ferromagnetism is observed in all films, which is not carrier mediated, but coexists with the dielectric behavior. A maximum magnetic moment of 2.37 {mu}{sub B}/Co is achieved by vacuum annealing due to the increase and diffusion of oxygen vacancies rather than the improvement of crystallinity of the film, and the magnetic moment decreases considerably after air annealing or increasing the oxygen partial pressure during deposition. The changes of oxygen vacancy concentration and distribution are indirectly demonstrated by the relative shifts of Co 2p{sub 3/2} peaks in XPS spectra. The band gap of Co-doped SnO{sub 2} film is larger than that of pure SnO{sub 2} film, suggesting the influence of inclusive Co on the electronic states, and further blueshift after annealing is also visible. The F-center model is modified to explain the ferromagnetism in insulating Co-doped SnO{sub 2} films.
- OSTI ID:
- 20979446
- Journal Information:
- Journal of Applied Physics, Vol. 101, Issue 12; Other Information: DOI: 10.1063/1.2747591; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANNEALING
ATMOSPHERES
COBALT
DEPOSITION
DIELECTRIC MATERIALS
DOPED MATERIALS
ENERGY GAP
F CENTERS
FERROMAGNETIC MATERIALS
FERROMAGNETISM
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
OXYGEN
PARTIAL PRESSURE
SPECTRAL SHIFT
TEMPERATURE RANGE 0273-0400 K
THIN FILMS
TIN IONS
TIN OXIDES
X-RAY PHOTOELECTRON SPECTROSCOPY