High-Density Recording Characteristics of Obliquely Oriented Particulate Magnetic Tapes by Removal of Disoriented Surface Layer
In order to achieve high recording densities, wide bandwidth and high output, a magnetic tape should have a high Bs, perpendicular orientation, a smooth surface, good head contact, and a small longitudinal component. By using a "LIPS" orienting process which produces media with a longitudinally oriented inside layer and a perpendicular oriented surface layer, we have fabricated obliquely oriented magnetic films based on acicular metal particles; of these, tape oriented at 45° had the widest-bandwidth characteristics. But a significant improvement in output was not obtained because of the existence of disoriented particles in the surface layer, resulting from calendering treatment. We tried to remove this surface layer using polishing sheets. An obliquely oriented (45°) tape exhibited an improvement in short-wavelength output (by 10 dB at 0.3 ¿m) after the thickness of the disoriented layer was reduced by 0.12 ¿m.
Analysis due to vector magnetic field for recording characteristic of metal evaporated tape
Metal-evaporated tape (ME tape) is one of the most promising materials for high-density magnetic recording. In a previous study, we reported that the recording characteristics of ME tape are directly affected by the columnar microstructure of the magnetic layer (Co-Ni-O magnetic film). In this study, we have conducted the theoretical analysis of the effects of both head motion and the vector magnetic field H θ , which is essentially parallel to the columnar longitudinal axis. The results of this analysis offer an effective explanation of the recording characteristics of ME tape.
Media for high density magnetic recording
Longitudinal recording is limited at high bit densities by recording demagnetization, self-demagnetization, and adjacent-bit demagnetization, which occur during the writing-demagnetization processes. To minimize these adverse effects it becomes necessary to resort to extreme scaling of the media parameters and their thickness, with the consequence of greatly increasing the difficulty of fabrication and the cost of such optimized media. Pure perpendicular recording circumvents these writing and demagnetization problems because of the strong head coupling of a single pole head with a double layer medium, positive interaction between adjacent bits, and low self-demagnetization at high bit densities. Therefore, it does not require any extreme scaling of the media magnetic parameters and their thickness. Of great interest, at least for the next several years, are the quasi-perpendicular particulate media which can support perpendicular magnetization. These include the isotropic, high-squareness media, and oriented perpendicular media employing particles with uniaxial crystalline or shape anisotropies. The attractiveness of these media derives from their excellent recording performance and from the fact that they preserve the existing head/media interface and they utilize existing coating facilities which should reflect favorably on their cost. In this paper the advantages and disadvantages of the various media under development for high density magnetic recording are compared, and predictions are made for their potential application in future systems.