Control of microstructure and magnetic properties in thin film disk by an ultra clean sputtering process

Migaku Takahashi

    Research output: Contribution to journalArticle

    1 Citation (Scopus)

    Abstract

    The ultra clean sputtering process (UC process) was recently introduced in the fabrication of Co based thin film media to establish the new concept of controlling the microstructure and magnetic properties. The relation between cleanness during film deposition process and magnetic properties has been discussed in connection with their microstructure. The main results are as follows. (1) By applying the UC process, high Hc values are realized in the media even with an extremely thin Cr underlayer. In the UC-CoCrTa, a high Hc of about 1.5 kOe remains at a Cr thickness of 2.5 nm. (2) The formation of Cr segregated grain boundary structure is strongly enhanced by applying the UC process, even in media with extremely thin Cr layers of 2.5 nm. (3) In the UC-processed media, the magnetostatic coupling mode is found to be the dominant type of intergranular coupling. A decrease in 4πMs/Hgraink below 1.0 is most effective to suppress the magnetostatic coupling due to the reduction in the grain size. (4) Absolutely high S/Nm is realized even in CoNiCr media owing to the marked decrease of intergranular exchange coupling. In media with grains sufficiently separated by segregated grain boundaries, the reduction of the grain size with decreasing Cr thickness is found to be effective for improvement of S/Nm. The UC process presented here enables the control of the fine structure of thin film media and results in excellent magnetic properties. This study demonstrates that the UC process is markedly superior to the normal process currently used and should play a dominant role in thin film fabrication.

    Original languageEnglish
    Pages (from-to)15-22
    Number of pages8
    JournalMaterials Chemistry and Physics
    Volume51
    Issue number1
    DOIs
    Publication statusPublished - 1997 Oct

    Keywords

    • Coercive force
    • Cr segregated grain boundary
    • Intergranular magnetic coupling
    • Recording performance
    • Thin film recording media
    • Ultra clean sputtering process

    ASJC Scopus subject areas

    • Materials Science(all)
    • Condensed Matter Physics

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