Observation of ferromagnetic behaviors in doped and undoped TiO$_{2}$ and ZnO

ORAL

Abstract

Transition-metal doping has been widely used to produce ferromagnetic oxides such as TiO$_{2}$ {\&} ZnO for use as a diluted magnetic semiconductor. Recently, however, undoped samples were also found to be ferromagnetic. We have studied the ferromagnetic behaviors of ZnO and TiO$_{2}$ single crystals and powders annealed both in vacuum and in flowing oxygen at various temperatures. In order to understand the observed ferromagnetism, we have used X-ray photoemission and electron spin resonance spectrometry to characterize the possible valance states or chemical bonding variation to study the roles that oxygen vacancies may have played in the occurrence of ferromagnetism. Comparisons on the doped and pure samples will be discussed.* Also with NSYSU .

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Authors

  • P.V. Wadekar

    • Dep. of Physics and TcSUH, University of Houston, TX
    • Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX.
    • Dept. of Physics and TcSUH,University of Houston, TX

  • Q.Y. Chen

    • Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX.
    • Dept. of Physics and TcSUH,University of Houston, TX
    • Dept. of Phy. and Center for Nanoscience and Nanotechnology, Natl. Sun Yat-Sen U./Dept. of Phy. and Texas Center for Superconductivity, U. of Houston

  • P.V. Chinta

    • Dept. of Physics and TcSUH,University of Houston, TX

  • O. Lozano

    • Dep. of Physics and TcSUH, University of Houston, TX
    • Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX.
    • Dept. of Physics and TcSUH,University of Houston, TX

  • Z.H. Zhang

    • Dept. of Physics and TcSUH,University of Houston, TX

  • W.K. Chu

    • Dep. of Physics and TcSUH, University of Houston, TX
    • Dept. of Physics and TcSUH,University of Houston, TX

  • H.W. Seo

    • Dep. of Physics, University of Arkansas, AR
    • Department of Physics, University of Arkansas, Little Rock, AR
    • Dept.of Physics, University of Arkansas,AR
    • Dept. of Physics, Univ. of Arkansas

  • Li-Wei Tu

    • Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
    • Dep. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, NSYSU, Taiwan
    • Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University NSYSU, Kaohsiung, Taiwan
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen Univ.

  • Li-Wei Tu

    • Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
    • Dep. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, NSYSU, Taiwan
    • Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University NSYSU, Kaohsiung, Taiwan
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen Univ.

  • Li-Wei Tu

    • Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
    • Dep. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, NSYSU, Taiwan
    • Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University NSYSU, Kaohsiung, Taiwan
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen Univ.

  • Li-Wei Tu

    • Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
    • Dep. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, NSYSU, Taiwan
    • Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University NSYSU, Kaohsiung, Taiwan
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen Univ.

  • Li-Wei Tu

    • Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
    • Dep. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, NSYSU, Taiwan
    • Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University NSYSU, Kaohsiung, Taiwan
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen Univ.

  • Li-Wei Tu

    • Department of Physics, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
    • Dep. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, NSYSU, Taiwan
    • Department of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan, Republic of China
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University NSYSU, Kaohsiung, Taiwan
    • Dept. of Physics and Center for Nanoscience and Nanotechnology, National Sun Yat-Sen Univ.