Investigations of a New Diluted Magnetic Oxide with Room Temperature Ferromagnetism in Co-doped HfO$_{2}$

ORAL

Abstract

The structural, chemical, and magnetic properties of HfO$_{2}$ epitaxial films $\sim $100nm thick grown on YSZ at varying growth temperature have been systematically investigated. Nearly cobalt cluster-free films with RT ferromagnetic behaviors can be obtained via low T growth. \textit{In-situ} XPS analysis during growth indicated the formation of metallic cobalt at the initial growth stage under a low O$_{2}$ partial pressure $\sim $10$^{-10 }$Torr, and that the metallic cobalt can be mostly eliminated by raising the pressure to 10$^{-7}$ Torr. In conjunction with EXAFS local structural analysis and post annealing experiments, we infer that cobalt ions in low T grown films are located at interstitial site and appeared to be stable after being annealed in O$_{2}$ at 350$^{\circ}$C. Further Hall measurements are now underway to measure the carrier concentration, and to elucidate their role to the apparent ferromagnetism.

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Authors

  • Y.H. Chang

    • Dept. of Materials science and Engineering, National Tsing Hua Uni., Taiwan

  • W.C. Lee

    • Dept. of Materials science and Engineering, National Tsing Hua Uni., Taiwan
    • Dept. of Materials Science and Engineering, National Tsing Hua Univ., Taiwan
    • Dep. of Materials Science and Engineering, National Tsing Hua Uni., Hsinchu, Taiwan

  • M.L. Huang

    • Dept. of Materials science and Engineering, National Tsing Hua Uni., Taiwan

  • S.F. Lee

    • Inst. of Physics, Academia Sinica, Taiwan

  • Y. L. Soo

    • Dept. of Physics, National Tsing Hua Uni., Taiwan

  • M. Hong

    • Dept. of Materials science and Engineering, National Tsing Hua Uni., Taiwan
    • Dept. of Materials Science and Engineering, National Tsing Hua Univ., Taiwan
    • Dep. of Materials Science and Engineering, National Tsing Hua Uni., Hsinchu, Taiwan

  • J. Kwo

    • Dept. of Physics, National Tsing Hua Uni., Taiwan
    • Dept. of Physics, National Tsing Hua Univ., Taiwan
    • Dep. of Physics, National Tsing Hua Uni., Hsinchu, Taiwan