Seiichi Onodera

11.5 Gb/in/sup 2/ recording using spin-valve heads in tape systems

We have investigated recording at densities higher than 4.5 Gb/in/sup 2/ in tape systems using spin-valve heads. We report the signal-to-noise ratio at areal recording densities of 4.5 Gb/in/sup 2/ and 11.5 Gb/in/sup 2/ on low-noise obliquely metal evaporated (ME) tapes. Also, we studied an electrostatic discharge failure of giant magnetoresistive heads on ME tape. The results indicate the feasibility of an areal density of 11.5 Gb/in/sup 2/ in a helical-scan tape system.

Advanced metal evaporated tape

This paper describes magnetic properties, recording characteristics and noise properties of metal evaporated (ME) tapes, especially for multilayer structures. Also the future potential of recording characteristics of ME tape is studied by a simulation method.

Magnetoresistive heads for helical-scan tape systems

In this paper, the helical-scan tape systems using the shielded MR heads will be discussed. We studied the issues related to the head/tape contact including the thermal asperity and the head wear. The study suggests that these issues can be resolved to the allowable level in the practical system. In this study, we have successfully demonstrated a high recording density using MR heads in these systems.

Investigation of Higher Recording Density Using an Improved Co–CoO Metal Evaporated Tape With a GMR Reproducing Head

To demonstrate the highest areal recording density of tape media, we have developed a metal evaporated tape with higher magnetic anisotropy of 2.5times10⁵ J/m³ and finer magnetic activation volume of 2.7times10^-24 m³ of a Co-CoO recording layer deposited on a smoother base film. A capability of an areal recording density of 23.0 Gb/in² was confirmed using a giant magnetoresistive head as a read head. The smoother surface roughness improved signal-to-noise ratio more than 2 dB

Recording characteristics of thin metal evaporated media in a helical-scan tape system with a spin-valve head

The recording characteristics of Co-CoO metal evaporated (ME) tapes with a giant magnetoresistive head have been investigated. The reproduced spin-valve head output was 7.6 times that of an anisotropic magnetoresistive head at a recording wavelength of 0.4 /spl mu/m. We also studied the relation between the carrier-to-media noise (C/N/sub media/) ratio and remanent magnetization (Mr) magnetic layer thickness (t) in the ME tape. The media noise level was reduced with decrease in Mr /spl middot/ t by the increase of the oxygen flow rate, whereas the C/N/sub media/ ratio of the tape with a magnetic layer thickness of 33 nm was maximized at around 10 mA. We thus confirmed the feasibility of an areal density of 3.8 Gb/in/sup 2/ in a helical-scan tape drive system.

Wear of the Mr head in the helical-scanning tape systems

In high-density recording in helical-scanning tape systems, MR head-wear caused by contact between the head and the tape is a critical item. We examine a method of measuring MR head-wear which can be calculated in terms of MR head resistance. We then compare wear as determined by the micro-indentation technique and this method. We then use this measuring method to investigate MR head-wear and gap recession depth using a variety of tapes. We found that by optimizing the asperity of advanced ME tape with a protective layer, MR head-wear can be reduced.

Recording over 15 ktpi using multichannel heads in a tape system

In magnetic recording systems, it has been reported that sufficient signal-to-noise ratio (SNR) was obtained with a narrow track width, using a spin-valve head and metal-evaporated tape. In order to apply this to a helical-scan tape system, techniques for writing narrow tracks and reading them exactly were required. However, the degree of mechanical accuracy demanded was too high to realize. With this in mind, we have developed multichannel heads which can write and read certain tracks with a single scan, as well as a nontracking technique removing the need for such precise mechanical accuracy. A prototype tape drive employing these techniques was developed, and a track density exceeding 15 ktpi was achieved.

Examination of newly developed metal particle media for >3 gb/in/sup 2/ recording in GMR-based tape systems

New metal particle (MP) media was developed for use with giant magnetoresistive (GMR) heads. We confirmed the capability of constructing a helical scan magnetic recording system exceeding 3 Gb/in/sup 2/ recording density, because of sufficient signal-to-noise ratio (SNR) under test conditions at 6.74 Gb/in/sup 2/ of read-track-base calculations with the media (magneticlayerthickness=50 nm, magneticparticlesize=45 nm, and surfaceroughness Ra=1.8 nm). Low media partial-abrasive properties are incorporated to avoid excessive head gap material wear.

Study of Perpendicular AME Media in a Linear Tape Drive

The magnetic recording performance of perpendicularly oriented advanced metal evaporated (AME) media is studied in a linear tape drive. A modified evaporation process produces the perpendicular orientation, which substantially reduces the writing asymmetry of obliquely oriented AME media in a linear recording environment. While the read back signal exhibits characteristics of perpendicular media, the timing-based servo signal in the drive enables track-following performance with a 1 sigma position error signal (PES) of 0.2 mum . The read channel correctable error rate at the LTO Gen 4 operating point is 10-6 in both the forward and backward directions and the durability of the tape exceeds 100 000 passes without signal degradation.

Metal Evaporated Media

Abstract This chapter reviews the development and the properties of metal evaporated media. Metal evaporated media is a mature tape technology, used for more than 20 years in magnetic recording systems for video and data storage applications. It also holds some of the highest areal densities on tape. We present the medium fabrication process and describe how the evaporation conditions control the medium microstructure, its magnetic and recording properties. Normally deposited with oblique incidence, the metal evaporated media show a characteristic tilted anisotropy and, as a result, a strong recording anisotropy that restrict their usage to unidirectional helical-scan recording systems. Recently, perpendicularly oriented evaporated media have been developed, which eliminate the recording anisotropy and enable the use of metal evaporated tape in linear tape systems. Tribological aspects of the metal evaporated technology are also reviewed, with an emphasis on the material developments that ensure the tape practical durability and archival stability.