Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1596656 | Solid State Communications | 2006 | 5 Pages |
Abstract
CoxTi1âxO2âδ films have been prepared on Si(001) substrates by sol-gel method. When heat treated in air, CoxTi1âxO2âδ films are non-ferromagnetic at room temperature. However, after further vacuum annealing or hydrogenation, CoxTi1âxO2âδ films show room-temperature ferromagnetism (RTFM). When the vacuum annealed CoxTi1âxO2âδ films are reheated in air, the magnetic moments of the films strongly reduce. After these films are vacuum annealed once again, the magnetic moments are greatly enhanced, confirming the role of vacuum annealing in ferromagnetism of CoxTi1âxO2âδ films. The x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and measurements of magnetization (M) vs temperature (T) fail to detect Co clusters in the vacuum annealed and the hydrogenated CoxTi1âxO2âδ films. Oxygen vacancies are formed in CoxTi1âxO2âδ films after vacuum annealing and hydrogenation, determined by XRD and XPS measurements. These results indicate that oxygen vacancies created by vacuum annealing and hydrogenation play an important role in the generation of RTFM in CoxTi1âxO2âδ films.
Keywords
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Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
L.F. Liu, J.F. Kang, Y. Wang, H. Tang, L.G. Kong, X. Zhang, R.Q. Han,