Observation of room temperature ferromagnetism in spray pyrolyzed polycrystalline Ti1−xCoxO2thin films
Year: 2009
Type: article
Abstract: We report here the room temperature ferromagnetic ordering in spray-pyrolized polycrystalline thin films of Ti 1− x Co x O 2 ( x = 0, 0.025, 0.05 and 0.10). The saturation magnetic moment in these films with x = 0.05 and 0.10 is estimated to be of 0.28 and 0.38μ B /Co, respectively. The ambient air employed in the present case of the spray pyrolysis process resulted in ferromagnetic films possessing very high resistivity values (∼10 7 Ω cm). This is in contrast to Ti 1− x Co x O 2 films deposited by vacuum based techniques, which are relatively conducting. While pristine TiO 2 film exhibited the anatase phase, the rutile phase of TiO 2 also evolved with an increase in Co concentration in these films. X-ray diffractograms could not reveal segregation of Co atoms in the TiO 2 matrix; also, no formation of any oxide of cobalt was detected. X-ray photoelectron spectroscopic investigation established the Co cations to be bivalent, and suggests that Co +2 is substituting Ti +4 in the TiO 2 matrix. Due to the highly resistive nature of these films, the observed room temperature ferromagnetism could be attributed either to the formation of bound magnetic polarons or to defect mediated ordering.
Institution: Indian Institute of Technology Delhi
Language: English
Topic: ZnO doping and properties
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2009797997