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Atomic-scale studies of cobalt distribution in Co–TiO2 anatase thin films: Processing, microstructure, and the origin of ferromagnetism
- Source :
- Journal of Applied Physics. 99:08M114
- Publication Year :
- 2006
- Publisher :
- AIP Publishing, 2006.
-
Abstract
- Using high-resolution, aberration-corrected, scanning transmission electron microscopy and electron-energy-loss spectroscopy we show that in films of single-phase anatase Co:TiO2, the Co distribution and magnetic properties are strongly dependent both on the overall crystalline quality and postgrowth vacuum annealing process. The Co:TiO2 films are coherent, epitaxial anatase with no secondary phases or metallic Co. Films of lower crystalline quality reveal a relatively homogeneous Co concentration, while films of higher crystalline quality show a tendency for Co enrichment near the surface region, around grain boundaries, and the substrate interface. Both uniform and nonuniform samples show a notable enhancement in the saturation magnetization with annealing, while the coercive field is considerably higher in the samples with uniform Co distribution. These experiments confirm that films of single-phase anatase Co:TiO2 with both uniform and nonuniform Co distributions exhibit room-temperature ferromagnetism in the insulating ground state, while the compositional uniformity and film microstructure play a role in the bulk magnetic properties of the material and the mechanisms for ferromagnetic ordering.
Details
- ISSN :
- 10897550 and 00218979
- Volume :
- 99
- Database :
- OpenAIRE
- Journal :
- Journal of Applied Physics
- Accession number :
- edsair.doi...........6b60089fc1bc777c9e6d6dee3aedc721
- Full Text :
- https://doi.org/10.1063/1.2170068