Segregated microstructure in sputtered Co‐Cr film revealed by selective wet etching

The segregated microstructure in a sputtered Co‐18.1 at. % Cr film is examined. Thin foil samples are prepared for transmission electron microscopy using selective wet etching and ion‐beam milling. The microstructure revealed by selective wet etching shows a definite striped pattern in each crystallite where the stripes run almost perpendicular to grain boundaries. Results of compositional analysis by an energy dispersive x‐ray microanalyzer reveal that these stripes are caused by dissolution of the Co‐rich ferromagnetic regions and that the remaining regions are Cr‐rich and nonmagnetic. The results are explained by a new model for segregated microstructure formation. Ferromagnetic Co‐rich regions are formed coherently in each single‐phase hcp crystallite, with a wall‐like structure perpendicular to the substrate plane. The observed microstructure suggests the existence of a magnetic unit far smaller than the crystallite diameter, which offers superior properties for high‐density perpendicular magnetic recording.

[1]  R. Fisher,et al.  Perpendicular anisotropy constants and anisotropy energy of oriented cobalt-chromium alloys , 1984 .

[2]  J. Judy,et al.  Particle‐like magnetic behavior of rf‐sputtered CoCr films , 1985 .

[3]  光弘 長谷部,et al.  Co-Cr系およびCo-Mn系状態図のコンピュータ解析 , 1982 .

[4]  F. Bolzoni,et al.  Magnetic properties and anisotropy of Co-Cr alloy , 1983 .

[5]  J. Sivertsen,et al.  Effects of a transition layer on CoCr films , 1985 .

[6]  M. Hansen,et al.  Constitution of Binary Alloys , 1958 .

[7]  N. Honda,et al.  Studies of the perpendicular magnetization mode in Co-Cr sputtered films , 1980 .

[8]  M. Kryder,et al.  Influence of deposition conditions on magnetic properties of CoCr thin films , 1985 .

[9]  C. Allibert,et al.  CoCr binary system: experimental re-determination of the phase diagram and comparison with the diagram calculated from the thermodynamic data , 1978 .

[10]  S. Luitjens,et al.  Evidence for microstructural inhomogeneity in sputtered Co‐Cr thin films , 1984 .

[11]  Kazuhiro Ouchi,et al.  Perpendicular magnetization structure of Co-Cr films , 1982 .

[12]  S. Iwasaki.  Perpendicular magnetic recording , 1980 .

[13]  M. Seki,et al.  TEM Observation of Segregated Microstructure in Sputtered Co–Cr Film , 1986 .

[14]  Shun-ichi Iwasaki,et al.  Perpendicular magnetic recording with a composite anisotropy film , 1979 .

[15]  K. Ouchi,et al.  Co-Cr recording films with perpendicular magnetic anisotropy , 1978 .

[16]  T. Yamashita,et al.  A comparison of the uniaxial anisotropy in sputtered Co–Re and Co–Cr perpendicular recording media , 1983 .

[17]  Y. Maeda,et al.  TEM Observation of Microstructure in Sputtered Co-Cr Film , 1985 .

[18]  一弘 大内,et al.  Co-Cr 垂直記録媒体の微視的偏析構造 , 1985 .

[19]  C. Faunce,et al.  Electron microscopy of Co-Cr films , 1984 .

[20]  Kazuo Kobayashi,et al.  Magnetic and structural properties of Rh substituted Co‐Cr alloy films with perpendicular magnetic anisotropy , 1981 .