Seagate Technology Incorporated

Western Digital Technologies, Inc.

Qingzhi Peng

Kathy X Tang

Hans Jürgen Richter

A method of detecting skip track erasure for a head and disk of a disk drive is disclosed. N tracks are DC erased, and a periodic pattern is written to the disk at a target track within the DC erased tracks. The periodic pattern is substantially comprised of a high frequency component greater than 450 MHz. After writing the periodic pattern to the target track at least twice, at least two of the DC erased tracks other than the target track are read to generate respective read signals. The read signals are processed to detect a skip track erasure event.

Writing high frequency pattern over a DC background to detect skip track erasure for a disk drive

A method of measuring the magnetic moment (Mt) and anisotropy field strength (H) of a perpendicular magnetic recording medium comprising a planar-surfaced perpendicular recording layer and a magnetically soft underlayer (SUL) is provided. A compensated magnetic moment (Mt)of the recording layer is determined for a given strength (H) of a generally in-plane magnetic field applied generally to the recording layer. The compensated magnetic moment (Mt)of the recording layer is determined for a plurality of different in-plane applied magnetic field (H) strengths to determine the variation of the compensated magnetic moment (Mt)of the recording layer as a function of the strength (H) of the generally in-plane applied magnetic fields. The remanent magnetic moment (Mt(0)) at zero (0) field strength (H) and the anisotropy field strength (H) is determined from the measured variation of the compensated magnetic moment (Mt)of the recording layer as a function of the strength (H) of the generally in-plane applied magnetic fields.

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Qingzhi Peng