Magnetoresistance of oxygen concentration-modulated Co–Ti–O films

Masatoshi Nakano, Fuxing Wan, Jian Wang, Takumi Sannomiya, Shinji Muraishi, Takashi Harumoto, Yoshio Nakamura, Ji Shi

研究成果: Article査読

1 被引用数 (Scopus)


Co–Ti–O films have been prepared by a sputtering method in an Ar- and O2-mixed atmosphere. The O2 flow rate was modulated during the deposition to optimize the oxygen concentration and the microstructure of the films. For the as-deposited film, negligible magnetization and magnetoresistance (MR) were observed. The structure of the layers with lower O2 flow rate is basically amorphous alloy with Ti–O and Co–Ti bonds. On the other hand, in the layers with high O2 flow rate, both Ti and Co are oxidized. Upon thermal annealing in a vacuum, significant enhancements in both magnetization and MR in Co–Ti–O films were observed. It is found that granular structure of Co particles embedded in insulating TiO2 matrix is formed due to the oxygen diffusion and further oxidization of Ti as a result of the heat treatment. The significantly enhanced magnetization and MR ratio have been ascribed to the formation of nano-sized Co particles and the tunneling conduction between these Co particles across the TiO2 interlayers, respectively.

ジャーナルApplied Physics A: Materials Science and Processing
出版ステータスPublished - 2018 6 1

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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