Investigation of advanced position error signal patterns in patterned media

Abstract

A potential approach to extending current thin film media to 100 Gbits/in2 recording density is physical patterning of the media, perhaps via an etching technique. An advantage of patterning is the capability of creating advanced position error signal (PES) patterns that are difficult or impossible to generate with writing by a recording head. This study uses spin stand tester to investigate various PES patterns generated by a focused ion beam etching technique on conventional thin film disks. For all practical purposes, the patterned PES eliminates transition noise, track edge noise, and erase band, therefore, demonstrates a much better PES signal than conventionally written servo patterns.

Recent Progress of Patterned Media

“…Arbitrary shape of the servo mark, which has not been written by a conventional servo track writer, can be obtained for the patterned media. Servo pattern with a shape of chevron or triangle has been reported [10]. Servo signal intensity is expected to become half that of the conventional one since the signal is generated by a pattern magnetized to the same (upward or downward) direction.…”

“…Servo signal intensity is expected to become half that of the conventional one since the signal is generated by a pattern magnetized to the same (upward or downward) direction. However, it is reported that the high signal-to-noise ratio (SNR) was obtained because of a clear magnetic transition at the edge of the servo pattern [10].…”

Magnetic block array for patterned magnetic media

“…Some have been done on recording or magnetization switching [3][4][5] and reading. 4,6 These media have been fabricated by various lithography methods including electron beam ͑EB͒, 1,2,7 optical interference, [8][9][10][11][12] x ray, 13,14 scanning probe microscope, [15][16][17][18] ion beam modification, 19 and focused ion beam ͑FIB͒ lithography. 6 The highest density array reported so far, that satisfies the necessary condition for recording media ͑i.e., single domain structure, uniformity of easy axis direction and so on͒ is 65 Gdot/in.…”