Takanori Kiya

Fe-Pt perpendicular double-layered media with high recording resolution

Abstract Design and preparation of a new Fe–Pt perpendicular double-layered medium are discussed. The Fe–Pt perpendicular medium with enhanced wall-pinning in a laterally exchange-coupled state showed high recording resolution and high thermal stability. An ultra-high reproducing resolution is expected to be verified for the medium if a narrower shield gap reproducing head would be used.

High density recording on ultra-thin Fe-Pt perpendicular composite media

Ultra-thin Fe-Pt films of perpendicular composite media were studied. It was found that a preparation condition at a temperature of 375/spl deg/C and introduction of an exchange-decoupling layer between the Fe-Pt layer and the soft-magnetic underlayer led to reduction of the initial growth layer of the Fe-Pt film. A 5 nm thick Fe-Pt medium exhibited a high SNR and a high recording resolution with high thermal stability.

Role of M-H loop slope of media for recording properties in perpendicular magnetic recording

Perpendicular magnetic recording media with a high resolution and a low noise property were studied using a micromagnetic simulation. It was suggested that the introduction of a small separation between the adjacent grains is effective to obtain such media increasing the perpendicular M-H loop slope without increasing the domain size. The separation is thought to reduce the demagnetizing field acting on the magnetic grains increasing the M-H loop slope of the grains.

(CoxFe100−x)–Hf–O granular films as back layers for perpendicular recording media

Abstract (Co x Fe 100− x )–Hf–O granular films with various B s and permeability were prepared as the back layers for perpendicular recording media. The effect of the permeability and B s of the backlayer on the write sensitivity, output voltage and medium noise were studied. The recording performance of the media with the granular backlayers was compared with that of the medium with an Fe–Si–N nano-crystalline backlayer. It was found that the medium noise and the write sensitivity did not depend on the permeability of the backlayer, while the output voltage and the reproduced sensitivity depend on the permeability and the B s . Compared with the Fe–Si–N backlayer, the media with the granular backlayer exhibited smaller transition noise. The noise sources for two types of the media are also discussed.

Noise spectrum analysis in perpendicular magnetic recording of double-layered media

Noise spectrum properties of double-layered perpendicular magnetic recording media were studied for two dominant medium noises, a transition jitter noise and a reversed domain noise. It was found that the transition jitter noise spectrum was delivered from the derivative of the transition shape, while the reversed domain noise spectrum was derived from a simple model of the impulsive reversed domain. The noise enhancement in a low-frequency region with increasing the recording density was found to be attributed to the relative increase in the jitter noise. The noise spectra for both sources were theoretically whitened when the transition width and the reversed domain size became negligibly small against reproducing resolution.

Head field evaluation by anomalous Hall effect of recording layer with soft underlayer

In order to evaluate head field of planar heads under the presence of both a recording layer and a soft underlayer without head-medium interface problem, an integrated system of a planar head with an anomalous Hall effect (AHE) element was proposed. Head field is detected by an AHE sensor formed in a recording medium of which layer structure is quite similar to that of regular recording media. Fabrication of the integrated planar head and its measurement result are described.

Recording Performance of Perpendicular Recording Media Measured by Contact Type Cusp-Field Write Head

In this paper, recording performance of the CoPtCr-SiO2 media is investigated by using contact-type cusp-field single-pole write head. The relationship between the microstructure of the storage layer and the recording performance is discussed.

Simulation study of nonlinear transition shift in perpendicular magnetic recording media

Recording resolution of perpendicular magnetic recording media is increased with an increased perpendicular M-H loop slope. In this paper, NLTS of double-layered perpendicular recording media with increased M-H loop slopes was investigated using micromagnetic simulation. It was concluded that increased NLTS of the media with increased M-H loop slopes is mainly caused by the decreased write field gradient due to decreased required write field for such media. It was also suggested that the demagnetizing field of a sharper magnetic transition causes an additional decrease in the write field gradient.

Co-Cr-Pt-Nb double layered perpendicular magnetic recording media with Pt/Ti intermediate layer

Summary form only given. Large magnetic anisotropy and perpendicular squareness, SQ/sub /spl perp//, are required for keeping thermal stability of perpendicular magnetic recording media. Compositional studies of the storage layer material and investigations of intermediate layers between the storage and the soft magnetic backlayer have been performed for obtaining such properties.