Western Digital Technologies, Inc.

Hitachi Global Storage Technologies Netherlands B.v.

Komag Corporation

Hgst Netherlands, B.v.

Western Digital (fremont), Inc.

Wd Media, LLC

Michael Alex

Gerardo Bertero

Xinzhi Xing

John Thomas Contreras

Eric J Champion

Manfred Ernst Schabes

Christopher B Wolf

Kroum Stanimirov Stoev

Nobumasa Nishiyama

Andreas Moser

Xiaodong Che

Michael Paul Salo

David E Wachenschwanz

Li Tang

Bogdan Florin Valcu

Zhen Jin

Mazin Almaqablah

Technology for improved data detection using machine learning may include a method in which an analog read signal comprising data read from a non-transitory storage medium of the data storage device is received. The analog read signal is processed into a plurality of digital samples. A digital sample from the plurality of digital samples is classified into a category from a plurality of categories using a machine learning algorithm for at least some of the plurality of digital samples. The plurality of digital samples is then decoded based on at least some of the predicted categories.

Machine learning-based read channel data detection

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

Systems and methods for forming implanted capping layers in magnetic media for magnetic recording are provided. One such method includes providing an underlayer, providing a magnetic recording layer on the underlayer, the magnetic recording layer including a bottom surface and a top surface where the bottom surface is between the top surface and the underlayer, and implanting a capping material in the top surface of the magnetic recording layer using a direct implantation technique or an indirect implantation technique.

Systems and methods for forming implanted capping layers in magnetic media for magnetic recording

A data storage device is disclosed comprising a disk comprising a plurality of tracks, and a head actuated over the disk. A first test pattern having a first polarity is written to a target track, and the first test pattern is read to generate a first read signal. The first test pattern is overwritten with a second test pattern having a second polarity opposite the first polarity, and the second test pattern is read to generate a second read signal. A defect in the target track is detected based on the first read signal and the second read signal.

Data storage device detecting media defects by writing opposite polarity test pattern

A perpendicular magnetic recording (PMR) disk used in energy assisted magnetic recording drives is described. The PMR disk includes a substrate, a magnetic recording layer disposed above the substrate, an exchange coupling layer disposed above the magnetic recording layer, and a capping layer disposed above the exchange coupling layer. The capping layer has a Curie temperature greater than the Curie temperature of the magnetic recording layer.

Energy assisted magnetic recording medium capable of suppressing high DC readback noise

A disk drive is disclosed comprising a head actuated over a disk, wherein the head comprises a laser for heating the disk while writing data to the disk. The disk drive receives write commands, and increases a power of the laser to a write power for heating the disk while writing data to the disk. A calibration interval is adjusted based on the power applied to the laser over time, and the write power is calibrated at the calibration interval.

Disk drive calibrating a laser write power for heat assisted magnetic recording

A disk drive is disclosed comprising a head actuated over a disk, wherein the head comprises a write element, a read element, and a laser operable to heat the disk while writing data to the disk. The disk is magnetized by writing a first test pattern to the disk using the write element and a first power applied to the laser. The magnetization of the first test pattern is destabilized by heating the disk using a second power applied to the laser, wherein the second power is less than the first power. After destabilizing the magnetization of the first test pattern, the first test pattern is read with the read element to generate a read signal, and the read signal is evaluated to detect a defect on the disk.

Disk drive destabilizing magnetization of test pattern using head laser to enhance defect detection

A perpendicular magnetic recording write head that a write pole, an electrically conductive coil coupled to the write pole for generating magnetic flux in the write pole in the presence of electrical write current, and a spin torque oscillator (STO) that injects auxiliary magnetic flux to the write pole in a direction generally orthogonal to the write pole to facilitate magnetization switching of the write pole. The STO comprises a stack of layers including electrodes, a pinned ferromagnetic layer having a fixed, a free ferromagnetic layer having a magnetization free to rotate, and a nonmagnetic spacer layer between the pinned and free layers. The free layer may be oriented either substantially orthogonal to the write pole or substantially parallel to the write pole, in which latter embodiment a flux guide may be located between the free layer and the write pole for directing the auxiliary magnetic flux from the free layer to the write pole.

Perpendicular magnetic recording write head with spin torque oscillator for fast switching of write pole magnetization

An interconnect between the write driver and the write head in a magnetic recording disk drive enables an inherent write current overshoot. The interconnect includes an integrated lead suspension (ILS) and a short flex cable that connects the write driver circuitry to the ILS. The interconnect is a two-segment transmission line, with the first segment connected to the write driver having multiple sub-segments or sections with non-uniform impedance levels. The section of the first segment that connects to the write driver is the short flex cable and has an impedance substantially higher than the source impedance Zof the write driver. The multiple sections of the first segment have non-uniform impedance values that have an effective impedance Zthat substantially matches Z. The second segment of the transmission line has an effective impedance Zthat is substantially less than Z. The write lines for the +W and &#x2212;W signals are preferably interleaved on the transmission line sections.

Magnetic recording disk drive with write driver to write head transmission line having non-uniform sections for optimal write current pulse overshoot

A perpendicular magnetic recording system has a write head having a main helical coil (the write coil) and main pole (the write pole) that directs write flux in a direction perpendicular to the recording layer in the magnetic recording medium, and an auxiliary coil and auxiliary pole that injects magnetic flux into the write pole at an angle to the primary or perpendicular axis of the write pole. The auxiliary coil is preferably a helical coil wrapped around the auxiliary pole. The additional flux from the auxiliary pole, which is injected non-parallel to the primary magnetization of the write pole, exerts a relatively large torque on the magnetization of the write pole, thereby facilitating magnetization reversal of the write pole. Electrical circuitry is connected to the main coil and the auxiliary coil to generate the auxiliary flux simultaneous with the switching of the magnetization of the write pole.

Perpendicular magnetic recording system with helical write coil and auxiliary coil for fast switching of write pole magnetization

A hard disk drive (HDD) including a magnetic disk, the magnetic disk including a data track. The HDD also includes a synchronized rewrite controller for synchronizing a plurality of rewrites of a data pattern on a location of the track of the magnetic disk and the HDD includes a write head controlled by the synchronized rewrite controller for writing the data pattern on the location of the data track and rewriting the data pattern a plurality of times on the location in synchronization with a prior writing of the data pattern on the data track.

Synchronized rewriting of data

A method for controlling proximity of a read element of a perpendicular-magnetic-recording (PMR) head to a PMR disk. The method includes: a) writing recorded data with a write element of the PMR head to the PMR disk; b) providing a proximity-control setting to a proximity-control element; c) positioning the read element of the PMR head with the proximity-control element as determined by the proximity-control setting in communication with the PMR disk for reading recorded data back from the PMR disk; d) measuring a resolution of a read-back signal of recorded data on the PMR disk associated with the proximity-control setting; e) determining if the resolution measured for the read-back signal of recorded data on the PMR disk satisfies a criterion for the resolution of the read-back signal of recorded data; and, f) changing the proximity-control setting, and repeating b), c), d) and e), unless the resolution satisfies the criterion.

Method and apparatus for controlling fly-height of a perpendicular-magnetic-recording head in a hard disk drive

The present invention provides a method and apparatus for quantifying stress and damage in magnetic heads. A change in a performance parameter of a magnetic recording head is characterized. The head is stressed by loading it onto and flying it over a rough zone of the recording medium. A post-stress read-back signal is read from the bit pattern written on the recording medium using the head subsequent to the stressing of the head. A performance parameter of the head is calculated using the post-stress read-back signal. The performance parameter of the head calculated using the post-stress read-back signal is compared to a performance parameter of the head calculated using a pre-stress read-back signal to characterize a change in performance of the head resulting from the stressing of the head.

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Fremont, CA, United States of America

Michael Alex