Disk drive integration issues for perpendicular recording

Abstract

In addition to achieving high areal density, recording with perpendicular media must be compatible with other elements of disk drive recording. These include use of rotary actuation, the need for offtrack capability, stray field immunity, and servo control of the head position. Rotary actuation implies writing and reading with the head skewed at substantial angles relative to the track, while servo requires clean track edges. A soft magnetic underlayer, while improving the perpendicular write efficiency, exacerbates problems with head skew and stray fields. We have performed experiments related to drive integration, at the component level and by building drives incorporating perpendicular media. We report on the effect of head skew on the drive, particularly for servo and data recovery. We report on a beveled probe head design which minimizes the effect of skew on the servo pattern and track squeeze. In a 20 Gbit/in 2 drive, perpendicular media yields comparable servo and nearly equal areal density performance to longitudinal recording.

Impact of Media Design on Track Edge in Perpendicular Magnetic Recording

“…Track edges in longitudinal recording have been the focus of many reported investigations [2]- [4]. The impact of head design on track edges in perpendicular recording has also been reported [5]- [8]. In this study, we focus on understanding the impact of media design on the track edges in perpendicular magnetic recording.…”

A New Single-Pole-Type Head Trimmed by Focused Ion Beam at Wafer Level

“…It is effective to use the magnetic/nonmagnetic multilayered structure for the MP film because of the smaller remanence [4]. For the skew problem, trapezoid shape is necessary for MP [3]. The damascene method is known for the manufacturing process of MP with trapezoid shape [5], [6].…”

“…The development of the formation process of a main pole (MP) of single-pole-type writing head is important because the shape and remanence of the MP may deteriorate the recording properties. The pole-erase problem [2] and skew problem [3] are known as the problems due to the MP. The high remanence causes a pole erase which erases the recorded information on the track during reading.…”

Mechanisms of Minimum Skew Angle Actuation for Hard Disk Drives

“…Therefore, the adverse effects due to head skew are more significant for perpendicular recording. Zhou [3] revealed the effects of the head pole aspect ratio and skew angle on areal density in perpendicular recording. The track density and areal density can be increased more than 20% when the skew is 0° compared to that of 15° skew.…”

“…The utilization of voice coil motor (VCM) rotary actuator in hard disk drives (HDDs) results in skew angles between the read/write head and disk rotation direction. The system performance and achievable capacity of hard disk drives are excessively sensitive to the skew angle [1][2][3]. The difference in skew angle, between the ID to the OD can be as large as more than 30 degrees in conventional 3.5" and 2.5" VCM actuated HDDs.…”