Hitachi Global Storage Technologies Netherlands B.v.

International Business Machines Corporation

Western Digital Technologies, Inc.

Wd Media, LLC

Western Digital (fremont), Inc.

Andreas Moser

Hal Jervis Rosen

Harold H Gee

Bruce David Terris

David Thomas Margulies

Dragos I Mircea

Robert Fontana

Ching Hwa Tsang

Steven E Lambert

Dieter Klaus Weller

Eric Edward Fullerton

Jan-Ulrich Thiele

Hoa Van Do

Thien Nguyen

Bruce Alexander Wilson

Hemantha Kumar Wickramasinghe

Bernhard E Knigge

Yimin Hsu

Pierre-Olivier Jubert

Xiao Z Wu

James Terrence Olson

Hans Juergen Richter

Michael Alex

Natacha Frederique Supper

David E Wachenschwanz

Byron Hassberg Lengsfield, Iii

Robert E Eaton

Bogdan Florin Valcu

Manfred Albrecht

Walter Eugene Weresin

Steven Nowlen Guilliams

Daniel S Wolf

Michael R Madison

Toan Tang

Douglas N Bartholomew

A data storage device is disclosed comprising a head actuated over a magnetic media, wherein the head comprises a write coil, a laser configured to heat the magnetic media during a write operation, and a read element. A test pattern is written to the magnetic media by applying a current to the write coil and a first bias to the laser. A second bias is applied to the laser while the head passes over the test pattern, and then the test pattern is read from the magnetic media using the head to generate a first read signal. A first noise power of the first read signal is measured, and at least one parameter of a noise power function is generated based on the first noise power measurement, wherein the noise power function is a function of at least the bias applied to the laser.

Data storage device measuring HAMR media distributions

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a laser configured to heat the disk while writing data to the disk. At least four different laser powers are applied to the laser and a fly height of the head over the disk is measured at each laser power. A lasing threshold power for the laser is detected based on the measured fly heights.

Data storage device detecting lasing threshold of laser by measuring protrusion effect

A data storage device is disclosed comprising a head actuated over a disk. Data is written to the disk and read from the disk to measure a quality metric. A recording parameter is repeatedly adjusted and the quality metric is measured for each adjustment of the recording parameter. An operating value for the recording parameter is selected that corresponds to a substantially maximum areal density for the disk when the measured quality metric substantially matches a target quality metric.

Data storage device maximizing areal density based on a target quality metric

The present disclosure generally relates to a HAMR head and techniques and apparatus for HAMR writer pole length characterization. One or more bits may be magnetically written on a disk using a leading edge of the writer pole at a first polarity. The disk may be moved under a body of the writer pole to magnetically write the one or more bits in the disk at a second polarity that is opposite to the first polarity to generate a feedback pulse having a signal amplitude. The signal amplitude of the feedback pulse may be measured as a function of writing frequency. A first effective length of the writer pole may be determined based on the measurements.

HAMR writer pole length characterization

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a laser configured to heat the disk during write operations. A first test pattern written at a first laser power is read to generate a first track width metric and a first peak amplitude. A second test pattern written at second laser power is read to generate a second track width metric and a second peak amplitude. The first track width metric, the first peak amplitude, the second track width metric, and the second peak amplitude are processed to estimate a coefficient C of an error function. An operating write power for the laser is calibrated based on the estimated coefficient C of the error function.

Data storage device calibrating laser write power for heat assisted magnetic recording

Systems and methods for improving the accuracy of test measurements involving aggressor tracks written to the disks are provided. One such method involves erasing a circumferential band of a disk, writing a central track on the circumferential band, measuring and storing a first track profile of the central track, writing an aggressor track on each side of the central track at a preselected aggressor track offset from the central track, measuring and storing a track profile of the aggressor tracks at the preselected aggressor track offset, measuring and storing a second track profile of the central track, performing the prior actions exactly n times where n is greater than or equal to 1, determining an estimated distance between the aggressor tracks based on the respective track profiles, determining a selected measurement using the estimated distance between the aggressor tracks, and the first and second track profiles of the central track.

Systems and methods for improving accuracy of test measurements involving aggressor tracks written to disks of hard disk drives

Systems and methods for making fast measurements of channel performance metrics such as error margin and off-track recording capability in shingled magnetic recording are provided. One such method involves writing a plurality of shingled tracks on the disk, measuring an off track read capability (OTRC) of each of the plurality of shingled tracks, determining radial endpoints of the measured OTRC for each of the plurality of shingled tracks, determining an approximate radial center for each of the plurality of shingled tracks based on the respective OTRC radial endpoints, and measuring a channel performance metric at a range centered around the approximate radial center for each of the plurality of shingled tracks. In one such case, the channel performance metric involves error margin. One such system includes a processor coupled to a memory, a magnetic transducer, and a test platform, where the processor is configured to perform the method.

Systems and methods for fast measurement of channel performance metrics such as error margin and off-track recording capability in shingled magnetic recording

Systems and methods for improving accuracy of head positioning using existing servo patterns are provided. In one embodiment, a method for improving read head positioning is provided that comprises: writing a series of tracks over a range of read offsets to be calibrated; measuring a set of raw track profiles from the series of tracks; sampling the set of raw track profiles at a series of signal amplitude levels; constructing a reference track profile from the set of sampled track profiles; calculating a set of read offset deltas from each sampled track profile; merging the sets of read offset deltas into a set of average read offset deltas; and converting the set of average read offset deltas into a read offset correction table. A similar method for improving disk write head positioning is also provided which utilizes such a read offset correction table to eventually create write offset correction table.

System and method for improving head positioning

Magnetic memories and methods are disclosed. A magnetic memory as described herein includes a plurality of stacked data storage layers to form a three-dimensional magnetic memory. Bits may be written to a data storage layer in the form of magnetic domains. The bits can then be transferred between the stacked data storage layers by heating a neighboring data storage layer, which allows the magnetic fields from the magnetic domains to imprint the magnetic domains in the neighboring data storage layer. By imprinting the magnetic domains into the neighboring data storage layer, the bits are copied from one data storage layer to another.

Three-dimensional magnetic memory

A method according to one embodiment comprises determining a growth rate of an erase band width between an aggressor track and a substantially unerased portion of a data track on a magnetic medium during a first number of write cycles on the aggressor track; and estimating the erase band width, or derived parameter thereof, for or after a second number of write cycles on the aggressor track, the second number of write cycles being greater than the first number of write cycles.

Method, system, and computer program product for estimating adjacent track erasure risk by determining erase band width growth rates

An apparatus and method is disclosed for orienting the magnetic anisotropy of longitudinal patterned magnetic recording media. A disk-shaped longitudinal granular magnetic recording medium is provided having a high orientation ratio in the circumferential direction. The medium is then patterned to form a uniform array of magnetic islands. The magnetic islands are then irradiated with ions to increase the magnetic exchange coupling between the grains of each island. This aligns the axes of magnetic anisotropy of the individual grains with the average axis of magnetic anisotropy of the grains, thereby aligning the magnetic anisotropy of each island along the circumferential direction.

Longitudinal patterned media with circumferential anisotropy for ultra-high density magnetic recording

Three-dimensional magnetic memory having bits transferrable between storage layers

One embodiment in accordance with the invention is a method that comprises determining if a slider of a data storage device is to perform a read or write operation with a disk of the data storage device. If the slider is to perform the read or write operation, the slider is set at a grazing contact with the disk for a predefined time frame to perform the read or write operation. The predefined time frame is approximately how long the slider can be in grazing contact with the disk without experiencing any substantial instability. After the predefined time frame expires, the slider is caused to move out of contact with the disk.

Enabling intermittent contact recording on-demand

An apparatus, system, and method are disclosed for writing magnetically encoded data. A servo module positions a write head relative to a first land such that a first edge of the write head is positioned substantially over a first land edge of the first land. The write head has a radial width greater than the sum of a radial width of the first land and radial widths of interior and exterior grooves such that the write head is also positioned over at least a portion of a second adjacent land. The write head writes magnetically encoded data to the first land. The servo module further positions the write head relative to a second land such that the first edge of the write head is positioned substantially over a second land edge of the second land and the write head is not positioned over the first land.

Apparatus, system, and method for writing magnetically encoded data to discrete lands

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San Jose, CA, United States of America

Andreas Moser