Ikuya Tagawa

Write heads with pole tip consisting of high Bs FeCoAlO films

We investigated the magnetic properties, corrosion resistance, and microstructure for the sputtered FeCoAlO films, and the properties of write heads that use them for pole tips. The FeCoAlO films have soft magnetic properties as well as magnetic induction Bs /spl sim/ 2.2 T, which is equal to the Bs of pure-Fe. In-plane uniaxial anisotropy for the as-made films is almost unchanged though a magnetic field is applied during annealing, i.e., the magnetic annealing effect is negligible. The films have sufficient magnetic thermal stability and corrosion resistance to withstand magnetic head fabrication processes. For write heads with pole tips which consist of FeCoAlO films, the overwrite (O/W) and the nonlinear transition shift (NLTS) show about -35 dB and 13%, respectively. Therefore, these FeCoAlO films can be advantageously applied to writing heads.

High performance write head for 10 krpm HDD with high data rate recording up to 45 MB/s

Fundamental design considerations of the write head for a hard disk drive with a higher data transfer rate are described. With a shorter yoke, the eddy current damping can be suppressed effectively. The head inductance is also reduced by yoke length reduction so that the rise time of write current can be reduced. To reduce yoke length, we adopted a double layer coil, which enabled us to increase coil winding turns. With half yoke length and the coil turns increase, we successfully reduced the NLTS by about half. The FIB pole trimming at wafer level can make an appropriate pole shape for generating a highly efficient writing field.

Magnetic Recording on Magneto-Optical Media Using Merge Type Giant Magneto-Resistive Head.

TbFeCo media for perpendicular magnetic recording were developed by employing a NiP underlayer that controls the magnetic properties of a TbFeCo magnetic layer. Dynamic write-read characteristics were examined using a conventional merge-type giant magneto-resistive (GMR) head originally designed for longitudinal magnetic recording. A clear magnetic transition of 450 kFCI (kilo Flux Change per Inch), a high media signal-to-noise ratio (SNR), and acceptable overwrite properties were obtained by optimizing the magnetic properties of TbFeCo films. The thermal stability of a written bit in TbFeCo film is sufficient for practical application.

Efffct of write head dimension and material parameters on nonlinear transition shift at high frequencies

Data rates in commercial rigid drives are MIW exceeding 2OOMbiin2 and the linear remrding densities are exceeding 250kFC1, which was made possible by a combination of PRML channel and MR heads. At high data rates and for high linear densities, non-linear hansition shift (NLTS) causes performance errors in PRML channels. It is known that NLTS can be reduced by reducing the rising time of the write head field and by increasing the field gradient [1][2]. Moreover, it was reported that write heads with shorter yoke length provide an advantage with respect to reducing NLTS [3][4]. Dn the other hand, these are many dimension and material pammeters to consider for mite heads. We examined the relatiomhip between the frepuency characteristics of NLTS and the dimensions and materids of the write head based on numerical simulation.