Ferromagnetism of Co-doped TiO₂films prepared by plasma enhanced chemical vapour deposition (PECVD) method

Abstract

Ti1−xCoxO2 polycrystalline films have been prepared on Si(0 0 1) substrates by the plasma enhanced chemical vapour deposition technique at 280 °C without using any carrier gas. All the films show room-temperature ferromagnetic behaviours and no ferromagnetic clusters are detected by x-ray diffraction, x-ray photoelectron spectroscopy, atomic force microscopy, Raman and superconducting quantum interference device measurements as the doping concentration is lower than 4%. In addition, the formation of non-ferromagnetic CoTiO3 under heavy doping is considered to be responsible for the degradation of magnetization in Ti1−xCoxO2 polycrystalline films. Furthermore, saturated magnetization of Ti1−xCoxO2 films is found to decrease with the increasing duration of oxygen-plasma processing, indicating that the oxygen vacancies in the films play an important role in the generation of ferromagnetic Ti1−xCoxO2 films.

Effect of cobalt doping on the electronic, optical and photocatalytic properties of TiO2

“…Moreover, the binding energy difference between 2p1 and 2p3 is consistence with XPS data of Co 2þ [21,22]. Base on these evidences, cobalt ion in anatase lattice is at þ2 valence state.…”

Influence of transition metal doping on the structural, optical, and magnetic properties of TiO2 films deposited on Si substrates by a sol–gel process

“…The OII peak appears as a function of oxygen vacancies. The increase in the area ratio of OII peak to OI peak indicates the enhancement of oxygen vacancy content [ 24 , 29 , 30 ]. The area ratio is 0.18, 0.28, and 0.32 for TiO 2 , Ti 0.90 Co 0.01 O 2 , and Ti 0.97 Co 0.03 O 2 films, respectively.…”

Effect of oxygen vacancy and dopant concentration on the magnetic properties of high spin Co2+ doped TiO2 nanoparticles

“…However, for the low spin Co 3 + the difference between the 2p peak binding energies is 15.0 eV [17]. Further evidence of the 2+ state of Co is confirmed from the appearance of two strong shake up satellite peaks towards the higher binding energy sides of the Co2p core level peak [18]. Normally the metallic Co2p 3/2 peak appears close to 778.3 eV.…”