Abstract: According to one embodiment, address information is expanded on a bit map in order to generate original address information which is divided in a direction of the abscissa to form groups. The demodulated values of the original address information are obtained as original intra-group demodulated values. New address information is obtained and an arrangement pattern of bits in the servo area determined based on the new address information on a bit map formed by integrating obtained new address information items of the groups.

Abstract: Provided is a process for making a magnetic recording medium having a magnetically partitioned magnetic recording patterns, which comprises the following three steps (1), (2) and (3), conducted in this order: (1) a step of forming a magnetic layer on a non-magnetic substrate; (2) a step of removing surface layer portions of regions for magnetically partitioning the magnetic layer; and (3) a step of exposing the thus-exposed regions of the magnetic layer, from which the surface layer portions have been removed, to a reactive plasma or a reactive ion, to modify the magnetic characteristics of the regions of magnetic layer, whereby a magnetic recording pattern is formed which are magnetically partitioned by the regions of magnetic layer having the modified characteristics. Thus, a magnetic recording medium having an enhanced recording density and minimizing letter bleeding at writing can be made with a high efficiency.

Abstract: An object of the invention is to provide a magnetic recording medium which exhibits an excellent corrosion resistance. To this end, proposed is a magnetic recording medium including a magnetic recording layer in which: a magnetic body and a filling body alternately appear along a recording surface; and a layer made of a passivated metal or an alloy containing at least one passivated metal is formed in an interface portion between an area of the magnetic body and an area of the filling body.

Abstract: According to one embodiment, a disk drive has a magnetic disk and a magnetic head having a spin-torque oscillator. The disk drive further has a head amplifier IC configured to supply a write signal and a drive signal to the magnetic head. The write signal corresponds to write data. The drive signal is supplied to generate a high-frequency magnetic field. The head amplifier IC continuously supplies a drive signal of normal level to the spin-torque oscillator, and supplies a drive signal of high level higher than the normal level, only for a prescribed time after the polarity inversion of the write signal.

Abstract: According to one embodiment, a magnetic disk of a patterned media type, has a plurality of zones divided in radial direction on a magnetic recording surface. A plurality of segments which are included in each of the zones includes a data recording area composed of data recording unit of magnetic material and a first resync area in which a reference signal pattern for setting the timing of writing data in the data recording area has been recorded. The number of segments included in each of the zones is an integer and has a common divisor.

Abstract: A method and apparatus for controlling lubrication in hard disk drives. Hard disk drives often include lubrication on the disks to protect the disks from incidental contact with the head slider. Embodiments of the invention include lubrication control recesses on the air bearing surface (ABS) of the head slider. The recesses reduce air stagnation on the ABS and/or store excess lubrication that migrates from the disk to the head slider. By reducing build-up of lubrication and storing excess lubrication, the lubrication control recesses avoid failure that may occur as a result of the lubrication interfering with the ABS or the read/write elements of the head.

Abstract: According to one embodiment, a storage device includes a link information creation module and a read-ahead process module. The link information creation module creates link information for associating storage regions on a storage medium, which store a plurality of data included in a single file, in an order according to continuity of the plurality of data. The read-ahead process module performs a read-ahead of data stored in a storage region on the basis of the link information, the storage region being associated with a storage region of the storage medium which is designated by the data read request.

Abstract: A data storage apparatus and method. The apparatus comprises a mounting structure, a motor mechanically attached to mounting structure, and a data storage platter mechanically attached to the motor. The apparatus additionally comprises a single actuator arm comprising a first and second read/write data head or multiple radial movement mechanisms each comprising a read/write data head. The single actuator arm is configured to move axially along an arc and across a top surface of the data storage platter such that the first read/write data head has access to a first section and a second section of the data storage platter and the second read/write data head only has access to the second section of data storage platter. Each radial movement mechanism moves a different read/write data head radially all along a radius of the data storage platter and over and across different sections of the data storage platter.

Abstract: Various embodiments of the present invention provide systems and methods for determining fly height. For example, a system for fly height determination is disclosed that includes a head assembly disposed in relation to a storage medium, a write channel, and a read circuit. The read circuit is operable to receive information from both the head assembly and the write channel. A frequency determination circuit is included that is operable to receive a first signal from the read circuit corresponding to information received from the write channel and to provide a first fundamental frequency and a first higher order frequency based on the first signal, and the frequency determination circuit is operable to receive a second signal from the read circuit corresponding to information received from the head assembly channel and to provide a second fundamental frequency and a second higher order frequency based on the second signal.

Abstract: There are provided a method for manufacturing a magnetic recording medium which is excellent in terms of both the recording and reproduction characteristics and the thermal fluctuation characteristics without reducing the density and hardness of the perpendicular magnetic layer; a magnetic recording medium; and a magnetic recording and reproducing apparatus with which an excellent recording density is achieved, wherein, in the method for manufacturing the magnetic recording medium, at least a portion of the perpendicular magnetic layer 4 is formed as a magnetic layer having a granular structure that contains Co as a major component and also contains an oxide of at least one nonmagnetic metal selected from the group consisting of Cr, Si, Ta, Al, Ti, W and Mg; a target for forming the perpendicular magnetic layer 4 by the sputtering process is prepared so as to include an oxide of Co and a compound of Co and at least one nonmagnetic metal selected from the group consisting of Cr, Si, Ta, Al, Ti, W and Mg, and t

Abstract: A magnetoresistive magnetic head according to one embodiment uses a current-perpendicular-to-plane magnetoresistive element having a laminate of a free layer, an intermediate layer, and a pinned layer, the pinned layer being substantially fixed to a magnetic field to be detected, wherein either the pinned layer or the free layer includes a Heusler alloy layer represented by a composition of X-Y-Z, wherein X is between about 45 at. % and about 55 at. % and is Co or Fe, Y accounts for between about 20 at. % and about 30 at. % and is one or more elements selected from V, Cr, Mn, and Fe, and Z is between about 20 at. % and about 35 at.

Abstract: Provided is a method for manufacturing, in a simple process, a magnetic recording medium having a distinct magnetic recording pattern formed thereon. A method for manufacturing a magnetic recording medium having a magnetically-separated magnetic recording pattern MP, the method at least including; a first step of forming a first magnetic layer 11 on a non-magnetic substrate 10; a second step of forming a resist layer 12 on the first magnetic layer 11, the resist layer 12 being patterned in correspondence with the magnetic recording pattern MP; a third step of forming a second magnetic layer 13 so as to cover a surface of the first magnetic layer 11 having the resist layer 12 formed thereon; a fourth step of removing the resist layer 12 together with the second magnetic layer 13 formed thereon; and a fifth step of partially removing the first magnetic layer 11 or partially modifying magnetic property of the first magnetic layer 11.

Abstract: A magnetic recording hard disk drive (HDD) has at least one read/write head that accesses more than one disk surface. The HDD is able to transfer data to and from the host computer seamlessly without interruption during the time the head is being moved from one disk surface to another disk surface. Nonvolatile solid state memory is associated with pairs of disk surfaces. During the time of a head transfer from one disk surface in the pair to the other disk surface, data is read from or written to the associated nonvolatile memory. The data is first read from or written to one disk surface, then from or to the nonvolatile memory, and then, after completion of the head transfer, from or to the other disk surface, thereby allowing seamless uninterrupted transfer of data.

Abstract: A voice coil motor (VCM) is controlled by applying a bipolar square wave actuator current to the VCM and calibrating a back electromotive force (back-EMF) measurement on the VCM in response to the square wave actuator current. Back-EMF on the VCM is measured while an actuator arm coupled to the VCM is in motion, and the VCM is controlled to move the actuator arm in response to the measured back-EMF voltage.

Abstract: According to one embodiment, a lubricant agent comprises a fluorine polymer represented as follows: R1—O—(R3O)l(R4O)m(R5O)n(R6O)o(R7)p-R2 where, R1 is a perfluoroalkyl group of C1 to C10, R2 is an organic group including at least one of three or more polar groups and carbon-carbon pi bonding, R3, R4, R5, and R6 are perfluoroalkylene groups of C1 to C4, respectively, R7 is an alkylene group or the perfluoroalkylene group of C1 to C10, and l, m, n, o, and p each indicate zero or a positive integer and do not concurrently indicate zero.

Abstract: According to one embodiment, an information storage apparatus comprises a storage medium on which a first servo pattern having absolute position information and a second servo pattern having relative position information are recorded, a head configured to record and reproduce information on and from the storage medium, a recording signal generator configured to generate a control signal for making the head record a third servo pattern having absolute position information on the storage medium while positioning the head by using the first and the second servo patterns, and a data storage unit configured to store recording data for recording the third servo pattern on the storage medium.

Abstract: A back electromotive force detection circuit detects a zero-crossing point by comparing a back electromotive force Vu which occurs in at least one coil of a motor with a center tap voltage at a common node of the coils, and outputs a back electromotive force detection signal. A switching control circuit controls the switching states of multiple switching circuits based upon the back electromotive force detection signal, thereby adjusting the current flowing through the coils of the motor. A window generating circuit outputs a window signal at a predetermined level during a period obtained by multiplying the cycle of the back electromotive force detection signal by a predetermined coefficient before the detection of the zero-crossing point. The switching control circuit stops the switching operation of the switching circuit during a period in which the window signal is maintained at the predetermined level, thereby setting the state to the high impedance state that corresponds to a non-driving period.

Abstract: According to one embodiment, an information storage apparatus comprises a storage medium with a first servo pattern having absolute position information and a second servo pattern having relative position information, a pitch correction module configured to move a head with an initial feed pitch by using the second servo pattern by a target distance determined from the first servo pattern, and to correct the initial feed pitch based on a moving distance of the head and a target distance, a head position controller configured to position the head based on the initial feed pitch corrected by the pitch correction module and information of the first and the second servo patterns, and a recording signal generator configured to generate a control signal for making the head record the third servo pattern having the absolute position information.

Abstract: Various embodiments of the present invention provide systems and methods for determining fly-height adjustments. For example, various embodiments of the present invention provide storage devices that include a storage medium, a read/write head assembly disposed in relation to the storage medium (278), and a SAM based fly-height adjustment circuit (214). The storage medium (278) includes a plurality of servo data regions (110) that each include a servo address mark (154). The SAM based fly-height adjustment circuit (214) receives the servo address mark (154) from the plurality of servo data regions (110) via the read/write head assembly (276), and calculates a first harmonics ratio (445) based on the received data. The first harmonics ratio (445) is compared with a second harmonics ratio (450) to determine an error (365) in the distance (295) between the read/write head assembly (276) and the storage medium (278).

Abstract: A method includes: producing a readback signal using a recording head positioned adjacent to a recording medium, amplitude demodulating the readback signal to produce an amplitude demodulated signal, frequency demodulating the readback signal to produce a frequency demodulated signal, and using the amplitude demodulated signal and the frequency demodulated signal to determine contact of the recording head with the recording medium. An apparatus that can be used to implement the method is also provided.

Abstract: Disclosed are information recording/reading methods. The information recording method includes forming file data and metadata regarding the file data into recording information; dividing a predetermined recording medium into a plurality of zones when a recording mode is set; and recording file data and metadata, which are to be additionally recorded, in different zones.

Abstract: The present invention aims to provide a method of producing a magnetic recording medium which is a method of producing a magnetic recording medium having a magnetically-separated magnetic recording pattern, the method including: forming a magnetic layer on a non-magnetic substrate; then exposing a surface of the magnetic layer partially to reactive plasma, or a reactive ion generated in the plasma to amorphize the portion of the magnetic layer.

Abstract: According to one embodiment, a magnetic disk device, includes: a magnetic disk; a magnetic head; a writing module configured to write data to a predetermined first track in at least one of the areas by the magnetic head; a reading module configured to read, by using the magnetic head, data of a second track in the at least one of the areas; a first judging module configured to judge whether there is an error in the data read by the reading module; and a first recording module configured to associate and record in a storage module, when the first judging module judges that there is the error in the data of the second track, the at least one of the areas and the number of writing the data to the first track by the writing module.

Abstract: One general embodiment of the present invention is a magnetic read head including a magnetoresistive sensor where sense current flows in a stacking direction of the magnetoresistive sensor, i.e., perpendicular to the plane of the layers of the head. The magnetoresistive sensor comprises a free layer having a magnetization direction that is affected by external magnetic fields and includes a Heusler alloy layer and a Co-based amorphous metal layer, a fixed layer which is stacked with the free layer and has a fixed magnetization direction, and a non-magnetic intermediate layer between the free layer and the fixed layer.

Abstract: A quiet retraction method for regulating constant velocity while parking an arm within a disk drive is described. The method comprises the steps of: driving a motor for the arm using a first drive current for a first period; floating the motor; sampling a back electromotive force (bemf) for a first sampled voltage, while floating the motor; driving the motor with a second drive current during a second period in response to sampling the bemf; determining whether the second drive current exceeds a current limit; estimating the bemf using the first sampled voltage when the second drive current exceeds the current limit; driving the motor with a third current during a third period in response to estimating the bemf; wherein driving the motor with the first, second, and third currents quietly parks the arm, while regulating the constant velocity.

Abstract: According to one embodiment, a test device for a storage device includes: a module configured to acquire from the storage device a value corresponding to a signal level read from a magnetic disk through a magnetic head of the storage device, at a first timing at which an initial power of 0 or greater is supplied to a heater in the head and at a second timing at which a power to the heater is returned to the initial power after the power to the heater has been increased from the initial power, a periphery of a head element in the head has been expanded by the heater, and the element has been protruded toward a magnetic disk side; and a determiner configured to determine whether plastic deformation has occurred in the periphery of the element based on a difference between the values obtained at the first and second timings.

Abstract: Various embodiments of the present invention provide systems and methods for reducing head distortion. For example, various embodiments of the present invention provide storage devices that include a storage medium, a read/write head assembly, and an adaptive distortion modification circuit. The storage medium includes information that may be sensed by the read/write head assembly that is disposed in relation to the storage medium. The adaptive distortion modification circuit receives the information sensed by the read/write head assembly and adaptively estimates and implements a distortion compensation factor in the analog domain. In some instances of the aforementioned embodiments, the read/write head assembly includes a magneto resistive head. In such instances, the distortion compensation factor is designed to compensate for non-linear distortion introduced by the magneto resistive head.

Abstract: According to one embodiment, a recording method includes: skipping a track by a skip amount in a skip region smaller than an overall recording region on a magnetic recording medium by using an extra region that is unnecessary for securing a storage capacity to be provided by a storage device, the extra region being on the recording surface of the magnetic recording medium; and recording data while skipping the track in the skip region, wherein the skip region is set to a region in which a track to be recorded on the magnetic recording medium is expected to influence an adjacent track in accordance with at least one of a condition and a state of the storage device.

Abstract: A disk drive. The disk drive includes a head, a moving mechanism, a first peak filter, an adaptive peak filter, and a filter controller. The head is configured to read servo data on a disk at sampling frequency. The moving mechanism is configured to move the head in proximity with a recording surface of the disk. The first peak filter has a fixed peak frequency and a variable gain, and is configured to be inserted into a servo loop. The servo loop is configured to position the head with position error signals between servo data read by the head and a target position. The adaptive peak filter has a variable peak frequency and a variable gain, and is configured to be inserted into the servo loop. The filter controller is configured to control the gain of the adaptive peak filter according to the gain of the first peak filter.

Abstract: According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, and an actuator. The magnetic disk stores data. The magnetic head floats due to an air flow produced by the rotation of the magnetic disk to write and read data to and from the magnetic disk. The actuator includes a suspension and an actuator arm. The suspension supports the magnetic head. The actuator arm supports the suspension. The actuator is provided with a strip projection, a bump, a plurality of projections, or a concave portion on the upstream side of an air flow produced by the rotation of the magnetic disk.

Abstract: To synchronize a write/read frequency with media with high precision even when a write head is positioned in a different zone in a magnetic recording/reproducing device equipped with patterned media formed with writing hit patterns and having a zoned format function, a write head is positioned on a recording track in the vicinity of a boundary between zones, and the write head is positioned in a different zone from the zone in which the read head is positioned, the preamble pattern in the zone in which the read head is positioned is reproduced, a difference between frequencies of the preamble patterns of the zones is compensated to determine a write frequency used for writing data into a desired track, and then start timing for writing is determined based on a synchronization pattern obtained at the position of the read head. Other systems and methods are presented as well.

Abstract: A method and apparatus for detecting predetermined surface characteristics in head gimbal assemblies to improve hard disk drive reliability. The predetermined surface characteristics include head slider protrusions such as scratches or contamination that can cause damage to the head or disk in hard drives. By detecting these protrusions, those drives with an increased chance of failure can be removed from a test group, thereby increasing the quality and reliability of the remaining disk drives. The invention provides a method of detecting these protrusions that is a more practical option than using a scanning electron microscope (SEM) to inspect each head slider.

Abstract: According to one embodiment, a magnetic recording medium includes a substrate and a single domain magnetic dot. The single domain magnetic dot is provided on the substrate and is written with a compensation signal for controlling the position of at least one of a recording device and a reproducing device. The single domain magnetic dot has a length in the radial direction of the substrate shorter than a length in the circumferential direction of the substrate.

Abstract: 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.

Abstract: A device and method for reducing power consumption of an optical drive are proposed. The present invention samples a carrier control signal and then compares the samples of the signals with predetermined threshold signals. According to the comparison result, the present invention increases or decreases an output signal index. The variation of the output signal index is used to control phases of diphase excitation control signals so as to control the rotation direction of a motor or make it stop. The present invention need not output the diphase excitation control signals continuously. It only needs to output a predetermined number of the diphase excitation control signals after the output signal index is increased or decreased. Hence, the present invention reduces the time for outputting the control signals and greatly reduces the power consumption of the optical drive thereby.

Abstract: According to one embodiment, a magnetic recording medium includes a disc substrate, a first recording layer, and a second recording layer. The first recording layer is disposed in at least one of a plurality of data storage areas partitioned in a radial direction on the disc substrate. A magnetic material is deposited on the first recording layer. The second recording layer is disposed in the data storage areas except the data storage area where the first recording layer is disposed. The second recording layer includes a magnetic material and a non-magnetic material that are alternately arranged in the in-plane direction of the upper surface of the disc substrate.

Abstract: A disk drive. The disk drive includes a disk configured to store data, a slider configured to fly in proximity to the disk, and a magnetic-recording head on the slider configured to access the disk. The disk drive also includes a moving mechanism configured to support and to move the head-slider, an adjustment portion configured to adjust clearance between the magnetic-recording head and the disk, and a controller configured to control the adjustment portion to control the clearance. The controller is configured to perform clearance control in a first mode in an operation selected from the group consisting of reading user data and writing user data according to a change in fly height of the slider after a load operation, and subsequently is configured to perform clearance control in a second mode in an operation selected from the group consisting of reading user data and writing user data.

Abstract: According to one embodiment, a magnetic recording medium to which a signal is recorded by reversing magnetization of a magnetic body, includes: a servo region to which a servo signal is written; a data region configured to include a magnetic region of a track to which data is written, the magnetic region being separated from other magnetic region of other track; and a periodic magnetic pattern region configured to be provided at a head portion of the data region following the servo region, and is inclined at a predetermined angle with respect to a circumferential direction of the magnetic recording medium, over a predetermined length in a radius direction of the magnetic recording medium.

Abstract: A system and method for providing a command queue selection scheme by selecting commands by giving preference to commands based on the power consumption characteristics the command. In one embodiment the selection scheme involves calculating the value of the cost of energy saving associated with the access of a command by an evaluation function Costi=EAT+C×F1 (seek distance, latency). C is a dynamically adjustable power control function that determines how much power decreases with the selection of a particular command and F1 is a functional calculation of the power consumption value associated with the particular command. In one embodiment commands with low power consumption will be accessed in preference to commands with shorter seek distance.

Abstract: A hard disk drive that includes a disk, and a head that is separated from the disk by a flying height. The disk drive also includes a circuit that determines the flying height from a signal read during a write operation of the drive. The circuit performs a calibration routine to determine a temperature dependent variable of the signal to offset any temperature effects on the signal used to determine the flying height. The calibration routine can be performed using a spacing error signal (“SES”) generated by the drive.

Abstract: A magnetic recording device according to one embodiment includes a magnetic recording medium having a magnetic recording layer; a recording element positioned on a head slider; an assistance element for supplying assistance energy to an area on the recording layer to which a recording magnetic field generated by the recording element is applied, the assistance element being positioned on the head slider; and a controller for controlling a size of an assistance area from the assistance element in accordance with a position of the head slider in a radial direction of the magnetic recording medium. Additional systems and methods are also presented.

Abstract: According to one embodiment, an electromagnetic conversion element positioning method includes: counting a servo clock for every servo sector radially extending on a recording medium, the servo clock being changed in synchronization with a change in rotation angle of the recording medium; reading magnetic information from spiral servo patterns with an electromagnetic conversion element, the spiral servo patterns being arranged at equal intervals in a circumferential direction of the recording medium, the spiral servo patterns having magnetic materials arrayed along a spiral line maintaining a defined inclined angle with respect to a circumferential line over a predetermined radial region; specifying a position of the spiral servo patterns on the circumferential line based on the read magnetic information; correlating the count value of the servo clock with the specified position; and specifying a radial position of the electromagnetic conversion element based on the correlated count value.

Abstract: A recording element substrate includes a recording element array including a plurality of recording elements, a drive circuit configured to drive the recording elements, and a heater located to surround the recording element array as viewed in a direction perpendicular to a surface of the recording element substrate and located above or below a capacitive element or a resistive element included in the drive circuit as viewed on a cross section of the recording element substrate.

Abstract: A disk drive. The disk drive includes a plurality of head-sliders, an actuator, a plurality of clearance adjustment sections, and a controller. Each head-slider includes a slider and a magnetic-recording head on the slider for accessing a disk for storing data. The plurality of head-sliders is secured to the actuator that is configured to move the plurality of head-sliders concurrently. Each clearance adjustment section corresponds to each head-slider of the plurality of head-sliders and adjusts a clearance of the corresponding head-slider. In addition, the controller is configured to position the actuator by servo control with a first head-slider selected from the plurality of head-sliders, to change a clearance of a second head-slider different from the first head-slider by controlling a clearance adjustment section of the second head-slider to bring the second head-slider into contact with a disk, and to detect the contact to measure the clearance of the second head-slider.

Abstract: According to one embodiment, an information storage device includes: a head reading user data and a start tag indicating a recording start position of the user data in each sector recorded on a medium, the user data and the start tag being read in order of the start tag and the user data; and a controller controlling the head to read a start tag recorded in a preceding sector arranged at a position to be read before a target sector with a movement of the medium, acquiring information on a recording start position of a user data recorded in the target sector based on the start tag read by the head and a relative positional relation between the preceding sector and the target sector, and controlling the head to read the user data recorded in the target sector.

Abstract: According to one embodiment, a storage apparatus includes: a storage medium configured to include a plurality of tracks; a head configured to write data to the storage medium; an auxiliary storage module configured to be able to store the data; and a controller configured to determine, during data writing, a write start position of the data, move the head to a track to which the data is to be written, start writing the data along the track when the head reaches the track, and store a piece of the data to be written between the write start position and the position where the data is started to be written into the auxiliary storage module.

Abstract: An apparatus, system and method for magnetic recording are disclosed. In at least one embodiment, the apparatus includes a first portion of a first magnetic medium having a first cross-sectional area, and a second portion of a second magnetic medium having a second cross-sectional area. The first and second portions are joined by way of a junction that allows for at least some ferromagnetic coupling therebetween. Additionally, the first and second cross-sectional areas are of differing extent in a first dimension so that a first ledge portion of one of the first and second portions extends past a first edge of the other of the first and second portions.

Abstract: A magnetic disk device includes a disk that includes a plurality of tracks and magnetically stores therein data; a magnetic head that reads and writes data on the tracks; a data writing unit that classifies sectors along one track into a plurality of sector groups and writes to a physical address of each of the sector groups data of a logical address that is different from a logical address corresponding to the physical address in same track; and a first nonvolatile memory that stores therein a conversion table of the logical address and the physical address.

Abstract: A magnetic recording disk drive has a patterned perpendicular magnetic recording disk of the type that has spaced-apart pillars with magnetic material on their ends and with trenches between the pillars that are nonmagnetic regions. A nonmagnetic capping layer is located in the trenches above the nonmagnetic regions. The substrate has diffusion material in the trenches that when heated will diffuse into the magnetic recording layer material and chemically react with it. The pillars are formed of material that will not diffuse into the recording layer. The recording layer is formed over the entire substrate and a nonmagnetic capping layer that is not chemically reactive with the diffusion material is formed over the recording layer in the trenches. The substrate is annealed to cause the recording layer material in the trenches and the material in the substrate to diffuse into one another and chemically react to render the trenches nonmagnetic.

Abstract: In BLDC motors driven via sensorless techniques, the BEMF signals in the motor coils may be used to detect the position of the motor such that speed of the motor may be accurately controlled. When detecting the BEMF signals, however, small perturbations occur which negatively impact the rotational torque of the motor. As a result, torque ripple may occur at regular intervals which may result in inefficiencies as well as audible noise. In various embodiments as described herein, the sampling of the BEMF signals may be done so at pseudo-random intervals such that the overall spectral energy that presents from the BEMF detections may be reduced at specific frequencies (such as fundamental sampling frequencies and harmonics thereof) and spread out over many more frequencies. Thus, despite the overall spectral energy being the same, the amplitude of any given frequency is lower as the sampling of the BEMF is less periodic.