Hydrothermal epitaxy of ferromagnetic cobalt doped titanium dioxide films at 120°C

Abstract

Epitaxial cobalt doped TiO2 anatase thin films were deposited on (001) oriented SrTiO3 single crystal substrates at 120°C by liquid phase deposition. X-Ray diffraction, photoelectron and absorption spectroscopies revealed that cobalt substituted Ti4+ predominantly as low spin Co3+ in the as formed films as a result of the oxidizing environment of the growth solution. Enhanced ferromagnetism was observed in films when annealed in vacuum and air as Co3+ was reduced to Co 2+ with no evidence of cobalt metal clusters forming. The insulating nature of the films indicated that ferromagnetism was not carrier-mediated but due to percolation of bound magnetic polarons. © 2011 The Royal Society of Chemistry.