Tetsuya Roppongi

Material properties and domain structure influence on pole erasure occurrence in perpendicular recording heads

The influence of the material properties and the domain structure of the yoke on pole erasure was investigated. A writer pole material with high anisotropy field (H/sub k/) can suppress pole erasure because it can create a 180/spl deg/ domain wall parallel to the head transverse direction. One of the causes of the pole erasure is due to the induced magnetic anisotropy in the pole tip region by the magnetoelastic effect.

Influence of magnetoelastic effect and domain structure on pole erasure occurrence in perpendicular recording heads

The influences of the magnetoelastic effect on the occurrence of pole erasure were investigated. It was found that the occurrence of pole erasure was related to the anisotropy energy induced by the magnetoelastic effect in the pole tip. The anisotropy energy by the magnetoelastic effect was dominated by the external stress on the pole tip and the magnetostriction of the pole film. The magnetization state in the yoke also influenced the occurrence of pole erasure. It was found that the yoke with large anisotropy energy in direction to the head height and the complex domain structure in the yoke made pole erasure worse.

Flying charactfristics of the shallow step pads slider for low flyfng

Lower flying height provides higher recording density in hard disk drives. The gas lubricating film thickness (flying height) between the magnetic head and the disk has been reduced to under 50 nm and various designs for the air bearing surface of the head slider have been discussed. To obtain high flying stability in very low flying conditions, it is important to achieve a high air bearing stiffness and to reduce the flying height fluctuation during head motion over the disk surface. We simulated the flying characteristics of the slider with shallow step air bearing pads and compared the simulated results with the experimental results. We also analyzed the air bearing stiffness, the flying characteristics during seek motion, the altitude sensitivity and the flying fluctuation due to the major manufacturing tolerances. The newly designed sliders have good characteristics for achieving a flying height around 25 nm.

Relationships between stray field on pole tip and occurrence of pole erasure

Perpendicular magnetic recording system has instability of data erasure on a hard-disk-drive due to remanent magnetization of writer pole tip, which is known as pole erasure. In previous works (2005), the authors reported the relationships between the occurrence of pole erasure and the material properties of writer pole film. Zhou and Zhu (2005) showed the physical size effect of pole tip on remanent magnetization of perpendicular recording head, and they measured the distribution of remanent magnetization in the pole tip by contact scanning recording techniques. In this study, the strength and distribution of stray field on pole tip are measured by MFM techniques. The relationships between occurrence of pole erasure, stray field strength, and material properties of writer pole film are also discussed.