Room temperature ferromagnetism in Co-incorporated TiO2 thin films

J Nanosci Nanotechnol. 2011 Mar;11(3):2743-6. doi: 10.1166/jnn.2011.2719.

Abstract

Observation of room temperature ferromagnetism (RTFM) in nano-crystalline Co-incorporated titanium dioxide [Ti(1-x)Co(x)O2(x = 0.05)] thin films prepared by spray pyrolysis technique is reported. While only the anatase phase was detected in as-deposited 5 at.% Co-incorporated TiO2 film, a small amount of rutile phase developed following its vacuum annealing. Besides, no X-ray diffraction peak corresponding to cobalt metal could be detected in any of the two films. SQUID magnetometry of both pristine and Co-doped thin films at room temperature elucidated distinct ferromagnetic behavior in 5 at.% Co-incorporated as-deposited film with saturation moment M(s) approximately 5.6 emu/cm3 which got enhanced up to 11.8 emu/cm3 on subsequent vacuum annealing. From the zero field cooled magnetization measurement we confirmed the absence of Co-metal clusters. The electrical resistivity was found to be greater than 108 omega-cm for the films. Based on the magnetic and electrical measurements the origin of RTFM has been attributed to the bound magnetic polaron (BMP) model.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cobalt / chemistry*
  • Crystallization / methods*
  • Macromolecular Substances / chemistry
  • Magnetics*
  • Materials Testing
  • Membranes, Artificial*
  • Molecular Conformation
  • Nanostructures / chemistry*
  • Nanostructures / ultrastructure*
  • Particle Size
  • Surface Properties
  • Temperature
  • Titanium / chemistry*

Substances

  • Macromolecular Substances
  • Membranes, Artificial
  • titanium dioxide
  • Cobalt
  • Titanium