Perpendicular Anisotropy Films Research Articles

Co-Cr Perpendicular Anisotropy Film Deposited by Evaporation with Ion Bombardment

Co-Cr Perpendicular Anisotropy Film Deposited by Evaporation with Ion Bombardment

Co-Cr Perpendicular Anisotropy Film Deposited by Evaporation with Ion Bombardment

Changes in CoCr films induced by argon ion bombardment during film deposition by evaporation were studied. The film magnetic properties and X-ray rocking curve widths indicated that ion bombardment during deposition results in greater film uniformity, with larger crystal grains, better crystal orientation and less Cr segregation. This is probably because ion bombardment promotes atomic diffusion in films, thereby reducing grain boundaries and other lattice defects.

垂直記録媒体のための無電解Ｃｏ‐Ｎｉ‐Ｒｅ‐Ｐ合金膜磁気特性へのタルトロン酸効果

Electroless plated Co-Ni-Re-P alloy films for perpendicular recording medium were investigated and developed. It was found that the addition of tartronic acid into the plating bath makes it possible to form the Co-Ni-Re-P perpendicular anisotropy films with noMnSO4 present. The Co-Ni-Re-P alloy film whose composition is simpler than that of the previously developed Co-Ni-Re-Mn-P films, has a higher potential than that of Co-Ni- Re-Mn-P alloy film from a practical use viewpoint as a perpendicular recording media. Readlwrite characteristics of 8 inch disks using Co-Ni-Re-P medium were also obtained and measured with a combination of a ring head. Characteristics whose quality was almost equal to those of Mn codeposited media were obtained, and a higher recording density would be expected with improvement in the matching condition between head and disk properties. The recording density of 54 kFRPI as D50 was obtained with 0.02 μm thick magnetic medium using a 0.33 μm gap length ring head at 0.12 μm head-medium spacing.

ポーラ・カー磁化曲線測定装置における磁場垂直度の精密測定法

The polar Kerr magnetooptical effect has been used as the main method to measure the magnetization characteristics of films with perpendicular magnetic anisotropy. The author found, however, that on some occasions the shape of the polar Kerr loop as well as the Hall loop changed remarkably (or drastically in some cases) with the orientation of the sample in the investigation of rare earth-transition metal alloy amorphous films. This is due to the cooperative effect of the in-plane or oblique component of magnetization in the sample film and the imperfect perpendicularity of the magnetic field in the polar Kerr apparatus. There is a possibility that such an effect leads to serious errors and misunderstanding in the measurement of perpendicular anisotropy films containing in-plane magnetic component, because some degree of deviation of field from the film normal is unavoidable in actual polar Kerr systems. Therefore, it is very important to examine the perpendicularity of the magnetic field of the magnet in the polar Kerr system before the experiment. However, it is difficult to measure the deviation angle of magnetic field by the ordinary techniques. This paper presents an original method to measure the perpendicularity of the magnetic field using an evaporated nickel thin film with oblique uniaxial magnetic anisotropy. In this method, the deviation angle of field can be obtained from the ratio of the maximum coercivity to the minimum one of the Hall or Kerr loop when the Ni film is rotated on the sample stage.

Effect of magnetic field in rf sputtering on the crystal orientation and magnetic properties of Co-Cr perpendicular anisotropy films

Co–23-wt. %-Cr alloy films with thicknesses of 0.3 to 2.5 μm were deposited using a conventional rf diode sputtering system when a magnetic field Hs less than 90 Oe is applied during deposition. As Hs increases, the hcp c-axis orientation normal to the film plane develops and the half-angle width of the rocking curve of the (002) line Δθ50 reaches to 3.5 deg at Hs more than 40 Oe. The development of the orientation is strongly related to the concentration of O in the films, which is lower in the films deposited in a magnetic field than those in a nonmagnetic field. The magnetic properties such as perpendicular coercive force Hc⊥ and saturation magnetization Ms strongly depend on the substrate temperature rather than Hs.

Co-Cr perpendicular recording medium by vacuum deposition

Magnetic and structural properties, crystal orientation, resistance to atmospheric corrosion, and depth profile of vacuum deposited Co-Cr perpendicular anisotropy films are presented. In contrast to the RF sputtered Co-Cr films having a rather small deposition rate, the present study confirms the applicability of vacuum deposition to the preparation of Co-Cr perpendicular anisotropy films at a deposition rate up to 6000 A/sec. It was found that films with relatively high magnetization and coercive force could be made which at the same time exhibited good corrosion resistance.

Perpendicular magnetic recording with a composite anisotropy film

For a recently proposed perpendicular recording system, a composite anisotropy medium has been developed to improve the recording sensitivity of the perpendicular recording head. The medium is composed of a Fe-Ni soft magnetic film and a Co-Cr perpendicular anisotropy film, which are successively deposited on a base by an r. f. sputtering. By using the new double layer medium, an extremely high recording sensitivity could be obtained, compared with the single layer Co-Cr medium. The recording current needed to saturate the double layer film decreased to one-tenth of that for the single layer Co-Cr film. Although the Fe-Ni layer was soft magnetic material, neither deterioration of the frequency response nor peak shift was observed for the double layer film. The reproduction with a perpendicular head was also investigated, and a high output voltage and a high signal-to-noise ratio were obtained.

An analysis for the magnetization mode for high density magnetic recording

By the analysis of the self-consistent magnetization and the direct observation of the remanent magnetization of a real tape, the authors discussed the obstacles which are, and will be, encountered in attaining a higher recording densities with the present magnetic recording system, which uses mainly a longitudinal magnetization mode. Then the properties of the three magnetization modes (longitudinal, circular, and perpendicular) are compared. The mode transformation is also discussed. Finally a new perpendicular magnetic recording system is proposed for high density recording. And some results of fundamental experiments are presented. The system uses the perpendicular magnetization mode which is basically free from the demagnetization in very high densities. Its realization mainly owes to the development of a perpendicular anisotropy film and perpendicular magnetic heads.