Influence of working pressure on the crystal structural and photo-magneto-electric properties of TiO2 thin films

Ya Xin Wang*, Zhi Jun Pei, Tong Li, Jian Ping Xu, Xin Wei Zhao, Kazuhiro Ohkawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Intrinsic TiO2 films were prepared by RF-magnetron sputtering at different working pressures (0.2 Pa-4.0 Pa). All as-deposited intrinsic TiO2 films show hysteresis behavior from 2 K to 340 K, and the largest room temperature (RT) saturation magnetization (Ms) is 1.96 emu/cm3 for the amorphous TiO2 film deposited at 2.0 Pa. From the X-ray diffraction (XRD) patterns of TiO2 films, we observe that the rutile and anatase crystal structures coexist in the TiO2 films at 0.2 Pa. With the working pressure increasing, the transformation between the rutile crystalline and anatase crystalline appears. When the working pressure is increased to 2.0 Pa, the crystalline state of TiO2 film changes from polycrystalline to amorphous. Using the high resolution transmission electron microscopy (HRTEM), we can observe the crystalline transformation by the electron diffraction pattern and HRTEM image clearly. The transmission spectra of TiO2 films are measured by the spectrophotometer, the visible (VIS) transmittance of TiO2 films is more than 85%, the absorption edge shifts to the longer wavelength with the amorphous transformation, and the Eg decreases to 3.14 eV, so the increasing structural defects play an important role in the ferromagnetism of intrinsic TiO2 films. In addition, all of as-deposited samples are high-resistance state and the resistivity is higher than 107 Ω·cm. We can rule out the effect of the carrier-mediated RKKY coupling on the system ferromagnetism.

Original languageEnglish (US)
Pages (from-to)1110-1115
Number of pages6
JournalGuangdianzi Jiguang/Journal of Optoelectronics Laser
Volume24
Issue number6
StatePublished - Jun 2013
Externally publishedYes

Keywords

  • Magnetization curve
  • RF-magnetron sputtering
  • TiO thin film
  • Working pressure

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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