Materials Transactions Online

Materials Transactions, Vol.46 No.08 (2005) pp.1802-1806
© 2005 The Japan Institute of Metals

Nanostructure of CoPtCr--SiO2 Granular Films for Magnetic Recording Media

Shunsuke Fukami1,, Nobuo Tanaka1,2,, Takehito Shimatsu3 and Osamu Kitakami4

1Department of Crystalline Materials Science, Nagoya University, Nagoya 464-8603, Japan
2EcoTopia Science Institute, Nagoya University, Nagoya 464-8603, Japan
3Research Institute of Electrical Communication (RIEC), Tohoku University, Sendai 980-8577, Japan
4Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Sendai 980-8577, Japan

Structural properties of CoPtCr--SiO2 magnetic recording films grown on Ru or Pt seed layers prepared by UHV-magnetron sputtering were studied by high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS) and energy filtered transmission electron microscopy (EFTEM). CoPtCr grown on Ru seed layers together with SiO2 forms a well-isolated structure composed of CoPtCr fine grains of 10 nm diameter surrounded by amorphous SiO2, whereas CoPtCr grown on Pt seed layers together with SiO2 forms a network structure composed of CoPtCr crystal of 5 nm size. These structural features made differences in their magnetic properties. The HRTEM and EFTEM studies revealed that cylindrical crystalline grains composed of CoPtCr and Ru are formed for CoPtCr--SiO2/Ru samples, whereas SiO2 are aggregated around the boundary between relatively large Pt grains and magnetic layers without obstructing the epitaxial growth of CoPtCr on Pt, not resulting in the cylindrical CoPtCr grains. Lattice spacings of CoPtCr grown on Pt with SiO2 are 0.7% expanded in comparison with CoPtCr grown on Pt without SiO2. The EELS studies suggested that Co and Cr atoms are partly oxidized by SiO2 addition for both samples and Cr atoms are more oxidized for CoPtCr--SiO2/Pt samples.

(Received 2005/3/28; Accepted 2005/6/6; Published 2005/8/15)

Keywords: CoPtCr--SiO2, perpendicular magnetic recording media, high resolution transmission electron microscopy, electron energy loss spectroscopy, energy filtered transmission electron microscopy

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