Abstract: A method of fabricating a near field transducer (NFT) in a thermally assisted magnetic recording (TAMR) head is disclosed. In some embodiments, the method includes: depositing a dielectric layer and a template layer on a waveguide core; patterning the template layer to form a template; depositing an Au NFT layer; planarizing the Au NFT layer to generate a planar layer; depositing an upper NFT layer; applying a peg patterning mask; etching the upper NFT layer and the planar layer that includes the Au NFT layer; removing the template; and depositing a dielectric material and planarizing an upper surface that includes the upper NFT layer.

Abstract: According to one embodiment, a magnetic disk device comprises a head position demodulation unit which demodulates a position of the head by performing switching between normal servo demodulation for processing servo information written to a servo sector of the disk and short servo demodulation for processing servo information by a short servo system, and a controller comprises a head position prediction unit which predicts a head position, and the head position prediction unit performs position prediction by using a latest head position obtained by demodulation by the head position demodulation unit and a head position obtained by past demodulation by normal servo demodulation.

Abstract: According to one embodiment, a magnetic disk device detects a first optimal fly amount, estimates a first optimal fly amount distribution, obtains a movable distance and an optimal moving speed of a magnetic head, detects a second optimal fly amount, moves the magnetic head to a plurality of movement positions specified based on the movable distance and the optimal moving speed while sequentially positioning thereat, and writes a plurality of spiral servo patterns to a magnetic disk while controlling the amount of protrusion of the magnetic head so that the spacing between the magnetic head at each of the movement positions and the magnetic disk becomes the first and second optimal fly amounts.

Abstract: An apparatus for a reworkable tape track following actuator includes a spring actuator, a head module, a voice coil, and a mounting body, where the spring actuator is coupled to the mounting body and the mounting body is removable from a tape drive assembly. The apparatus further includes the head module being coupled to a middle section of the spring actuator and the voice coil being positioned beneath the head module.

Abstract: According to one embodiment, a method of adjusting a magnetic recording and reproducing device is a method of adjusting a magnetic recording and reproducing device incorporating a heat-assisted magnetic recording head and a magnetic disk, and the method includes performing a first write operation at a first position on a recording surface, measuring a first error rate at a second position different in radial position from the first position, performing a second write operation and then measuring a second error rate, obtaining a first difference between the first error rate and the second error rate, measuring a third error rate at the first position, performing a third write operation and then measuring a fourth error rate, calculating a second difference between the third error rate and the fourth error rate, comparing the first difference with the second difference and determining a change in flying height.

Abstract: Methods are provided for managing defects in Hard Disk Drive (HDD) storage devices. In particular, only a portion of the cylinders of an HDD is tested. Machine learning modeling is used to reconstruct the data for the untested cylinders. An HDD comprises a rotating disk and a read/write head actuated above the disk surface. The disk may be formatted into concentric data tracks, with each track being divided into sectors. The tracks may be organized into zones (groups of tracks called cylinders), and the axially parallel sectors in each cylinder may be organized into wedges. In a test mode, some portion of the cylinders is chosen for testing. Each wedge in the chosen cylinders is tested and labeled defective or non-defective. The test data for each defective wedge is run through a machine learning defect management logic, and inferences are made for the defective/non-defective status of the untested wedges.

Abstract: A method of reading data from a rotating magnetic storage medium, having at least one read head, includes storing respective digitized data samples from each respective read head of the at least one read head in a respective timing buffer, determining a zero-phase start phase angle from a preamble of the digitized data samples, feeding forward the zero-phase start phase angle to an interpolator, selecting an interpolation filter based on the fed-forward zero-phase start phase angle, releasing the respective digitized data from the respective timing buffer after a duration sufficient for completion of the determining, the feeding forward and the selecting, and interpolating samples of the digitized data released from the respective timing buffer.

Abstract: An apparatus is configured to include a first magnetic layer, a second magnetic layer and a break layer between the first magnetic layer and the second magnetic layer. The first magnetic layer includes a Curie temperature gradient between a first surface and a second surface of the first magnetic layer. The second magnetic layer includes a Curie temperature gradient between a third surface and a fourth surface of the second magnetic layer. The first magnetic layer has an average Curie temperature that is higher than the second magnetic layer.

Abstract: Various illustrative aspects are directed to a data storage device comprising one or more disks, an actuator arm assembly comprising one or more disk heads and a voice coil motor (VCM), the VCM configured to operate in a PWM mode and a linear mode, and one or more processing devices configured to: seek the VCM towards a target track in the PWM mode; transition the VCM from the PWM mode to the linear mode, wherein the transitioning comprises switching an offset compensation value from a first offset compensation value to a second compensation offset value to compensate for a transition offset induced while transitioning the VCM from the PWM to the linear mode, wherein the first and the second offset compensation values correspond to the PWM and linear modes, respectively, and seek the VCM towards the target track in the linear mode for a linear mode time.

Abstract: A heat-assisted magnetic recording head includes a near-field transducer, a waveguide, and a resonance enhancing feature. The near-field transducer is configured to focus and emit an optical near-field. The waveguide is configured to receive electromagnetic radiation and propagate the electromagnetic radiation toward and proximal to the near-field transducer. The resonance enhancing feature is disposed proximal to the near-field transducer and to a media-facing surface of the heat-assisted magnetic recording head. The resonance enhancing feature includes a first segment and a second segment disposed on opposite sides of the near-field transducer relative to a cross-track dimension of the heat-assisted magnetic recording head. Each of the first segment and the second segment of the resonance enhancing feature includes a liner and a filler. The liner of each of the first segment and the second segment at least partially faces the near-field transducer.

Abstract: A method for digital timing recovery from oversampled analog signals includes computing filter coefficients for digitized samples of the oversampled analog signals based on an oversampling factor of the oversampled analog signals, using the filter coefficients in a rotation filter to compensate for the oversampling factor in the digitized samples of the oversampled analog signals, deriving a starting phase and magnitude from the compensated digitized samples of the oversampled analog signals, and using the starting phase and magnitude in a timing recovery loop to recover a clock from the compensated digitized samples of the oversampled analog signals. The rotation filter may include a plurality of taps, and the circuitry may be configured to compute respective sets of coefficients for respective taps. Each set of coefficients may be dependent on another set of coefficients, or the coefficients may be approximate with each set of approximate coefficients being independent.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a storage section, a first determination unit, and a first parity management unit. The first determination unit determines presence or absence of an unexecuted command. The first parity management unit searches the storage section for the first parity area after the first determination unit determines that there is no unexecuted command. The first parity management unit generates the first parity based on the first data in the first data area if the first parity area is detected as the invalid parity area, and writes the first parity to the first parity area.

Abstract: According to an embodiment, a magnetic disk is provided with a first area including a plurality of blocks and a second area designated as a write destination by a host. The first memory is a volatile memory that receives write data received from the host. A controller estimates a degree of influence of ATI for each of the plurality of blocks, and sets a first block in which the degree of influence of ATI reaches the first threshold value and two blocks adjacent thereto to be unwritable. The controller selects one of one or more blocks which are not set to be unwritable and have free space among the plurality of blocks, and stores a copy of write data in the first memory in the selected one block at least for a period until the write data is written to the second area.

Abstract: A heat-assisted magnetic recording head includes a laser, a near-field transducer, a primary waveguide, a secondary waveguide, and a photodiode. The laser is configured to emit electromagnetic radiation. The near-field transducer is configured to focus and emit an optical near-field. The primary waveguide configured to receive the electromagnetic radiation and propagate the electromagnetic radiation toward and proximal to the near-field transducer. The secondary waveguide configured to receive a portion of the electromagnetic radiation from the primary waveguide. The photodiode configured to receive the portion of the electromagnetic radiation from the secondary waveguide and emit a signal that represents a magnitude of the electromagnetic radiation that the laser emits.

Abstract: According to one embodiment, a magnetic disk device includes a disk, a write head, an adjustment unit, and a write processing unit. The adjustment unit adjusts each of a first adjustment value, a second adjustment value, and a third adjustment value. The write processing unit can select shingled magnetic recording and perform write processing based on the first to third adjustment values. When the number of the plurality of tracks of the band is t+1 and the number of unused sectors among the plurality of sectors of the band is e. The adjustment unit adjusts the first to third adjustment values to establish ext.

Abstract: A Data Storage Device (DSD) includes a disk to store data, at least one head to read and write data on the disk, and a Voice Coil Motor (VCM) to move the at least one head over the disk. An upper velocity limit is reduced for moving the at least one head to perform a command to read or write data at a target location on the disk as a precautionary measure against damaging the at least one head during an Emergency Power Off (EPO) state. The upper velocity limit is reduced in response to the target location being in an Outer Diameter (OD) region of the disk, a direction needed to move the at least one head being in an Inner Diameter (ID) to OD direction, and a starting position being at least as radially far from an OD region position as a predetermined threshold.

Abstract: A disk device according to one embodiment includes magnetic disks, a spindle motor, a housing, a first board, and a first connector. The magnetic disks are arranged in an axial direction. The spindle motor rotates the magnetic disks about a first rotation axis. The magnetic disks and the spindle motor are accommodated in an inner space in the housing. The housing includes a first wall having the spindle motor attached thereto, and a second wall protruding from the first wall to surround the inner space. The first board is attached to an outer surface of the second wall. The first connector is attached to the first board and is connected to an external device. Each of the magnetic disks has a diameter of 80 mm or more and 100 mm or less. The housing has a maximum dimension of 26.2 mm or more in the axial direction.

Abstract: According to one embodiment, a controller of a magnetic disk device calculates a first power amount that is an amount of power required for an unload operation of a magnetic head based on a state of a VCM while the VCM is operating. The controller calculates a first set value based on the first power amount. When an amount of second data that is first data stored in a volatile memory and not yet written to a magnetic disk exceeds the first set value, the controller executes a first write operation of writing a part or all of the second data to the magnetic disk. When supply of power from outside is interrupted, the controller executes the unload operation and saving of the second data to a nonvolatile memory by using power generated by a back electromotive force of the second motor.

Abstract: According to one embodiment, a magnetic disk device includes a read control system that extracts scrambled data from media data read from a medium and inspection data associated with a seed value at the time of write, generates inspection data for data extracted from the media data, obtains from the inspection data and inspection data extracted from the media data, a seed value associated with both, compares this seed value with the seed value expected by the controller, and evaluates, when the comparison result is a mismatch, the data as an error, whereas when match, descrambles the data extracted from the media data using the seed value.

Abstract: According to one embodiment, a disk device includes two magnetic disks opposing each other at intervals of 1.2 to 1.5 mm, and at least two suspension assemblies movable respectively between the two magnetic disks. Each of the suspension assemblies includes a base plate, a load beam extending from the base plate, a tab extending from a distal end of the load beam, a wiring member on the load beam and the base plate, including a gimbal portion, and a magnetic head on the gimbal portion, abutting on a dimple of the load beam via the gimbal portion. The ratio of a distance from a bendable location of the load beam to a center of the dimple with respect to a distance from the center of the dimple to a tip of the tab is 2.8 to 3.8.