Phys. Rev. Lett. 95, 217203 (2005) [4 pages]Negligible Magnetism in Excellent Structural Quality CrxTi1-xO2 Anatase: Contrast with High-TC Ferromagnetism in Structurally Defective CrxTi1-xO2Received 1 July 2005; published 14 November 2005 We reexamine the mechanism of ferromagnetism in doped TiO2 anatase, using epitaxial Cr∶TiO2 with excellent structural quality as a model system. In contrast to highly oriented but defective Cr∶TiO2 (∼0.5μB/Cr), these structurally superior single crystal films exhibit negligible ferromagnetism. Similar results were obtained for Co∶TiO2. We show for the first time that charge-compensating oxygen vacancies alone, as predicted by F-center mediated exchange, are not sufficient to activate ferromagnetism. Instead, the onset of ferromagnetism correlates with the presence of structural defects. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.95.217203
DOI:
10.1103/PhysRevLett.95.217203
PACS:
75.25.+z, 75.50.Pp
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