Abstract: A method for making a master disk to be used for nanoimprinting patterned-media magnetic recording disks uses sidewall lithography. In one implementation, the master disk substrate has a first pattern of concentric rings formed on it by sidewall lithography, followed by a second pattern of generally radially-directed pairs of parallel lines, also formed by sidewall lithography, with the pairs of parallel lines intersecting the rings. An etching process is then performed, using the upper pattern as an etch mask, to remove unprotected portions of the underlying concentric rings. This leaves a pattern of pillars on the substrate, which then serve as an etch mask for an etching process that etches unprotected portions of the master disk substrate. The resulting master disk then has pillars of substrate material arranged in a pattern of concentric rings and generally radially-directed pairs of parallel lines.

Abstract: A method and apparatus for improving the capacity of a hard disk drive is provided. In one embodiment, a portion of timing information is written to a first disk prior to coupling the first disk with a hard disk drive. The first disk is then coupled with the hard disk drive having a read element aligned with a write element on a head portion of a head gimbal assembly. The timing information is then provided to the read element during a writing of a set of servo track information on the disk, wherein the portion of timing information allows the read element to be aligned with the write element on the head during the writing of the set of servo track information.

Abstract: A thermally-assisted recording (TAR) patterned-media magnetic recording disk drive has a perpendicular patterned-media disk with multilevel data islands and a laser capable of supplying multiple levels of output power to a near-field transducer (NFT). If there are only two cells in each island, each island is formed of an upper cell of magnetic material with a coercivity HC1 and a Curie temperature TC1, a lower cell of magnetic material with a coercivity HC2 and a Curie temperature TC2 greater than TC1, and a nonmagnetic spacer layer between the two cells. Each cell is formed of high-anisotropy material so as to have an anisotropy field greater than the magnetic write field. The TAR laser is capable of supplying at least two levels of output power to the NFT to allow the islands to be heated to two distinct temperatures so that the two cells in an island can be written so as to have either the same or opposite magnetizations.

Abstract: A magnetic write head for perpendicular magnetic recording having a stitched notched trailing shield. The trailing shield includes a first pedestal portion having sides that are self aligned with the sides of the write pole and having a back edge that extends a first shield throat height. The shield further includes a second shield portion stitched onto the pedestal portion, the second shield portion having a back edge that extends beyond the back edge of the pedestal portion.

Abstract: UV curing of adhesives with light beam shaping utilizes a spot curing process that focuses a limited amount of UV light onto a target area, such as glue dots. A focusing lens may be used to direct the UV light beam to the target area. The target areas have different geometrical shapes, and the UV light is advantageously concentrated in a more efficient manner. Beam-shaping optics or lenses are used to facilitate re-shaping and re-defining the UV-light beam. The UV beam may be defined and limited to a rectangular spot to improve the spot process quality and efficiency.

Abstract: An embodiment of a magnetic disk apparatus in accordance with the present invention includes a magnetic recording medium, a magnetic head assembly having a magnetic head which reads and writes data on the magnetic recording medium, and a motor coil assembly rotationally driving a spindle motor rotation body, in which plural motor coils are arranged on a circumference around the rotation center of the spindle motor rotation body so that intervals in the circumferential direction are equal, in a stator base surrounding a periphery of the spindle motor rotation body and having a shape in which a prescribed moving locus portion of at least the magnetic head assembly is cut out.

Abstract: An advanced process control (APC) system. The APC system comprises a database for receiving process data from a measurement tool for a plurality of process runs and for storing the process data. A lambda tuner determines a tuned-lambda value corresponding to a process-capability-index value based on upper and lower process control limits and statistics derived from the process data. A process-run controller updates a recipe value based on the received process data and the tuned-lambda value.

Abstract: A method for fabricating sliders (magnetic heads) with a recessed surface around a magnetic feature such as the active components of the write head on the air-bearing surface (ABS) is described. An embodiment of the method applies a positive photoresist to the exposed ABS surface, a magnetic field is applied, then liquid ferrofluid is applied on top of the photoresist. The pole pieces around the write gap will interact with the applied magnetic field so that the field gradient is highest around the write gap and the mobile ferrofluid will preferentially collect in the areas of the surface having the highest magnetic field gradient. The opaque magnetic particles in the ferrofluid form an optical ferrofluid mask over the photoresist around the write gap. The unmasked surface of the slider is milled which results in the recession of material around the write gap.

Abstract: A magnetic head comprises a retrieving unit for converting magnetic information output from a recording medium into an electric signal, a writing unit having the function of electromagnetic conversion for writing the magnetic information in the recording medium in response to the electric signal, and a first protective film formed on the retrieving unit. A second protective film is formed on the first protective film. The coefficient of linear expansion of the second protective film is reduced in comparison with that of the first protective film. Furthermore, the first protective film is an alumina film; in contrast, the second protective film is a film made of an alumina film containing silicon oxide therein.

Abstract: Techniques are provided for iteratively decoding data recorded on a data storage device. An iterative decoder decodes the data using multiple decoding iterations to correct errors. In multiple iterations of the iterative decoder, a post processing block generates soft information, and a decoder applies a minimum sum decoding algorithm to a low density parity check (LDPC) code to generate extrinsic information based on the soft information and updated soft information.

Abstract: Techniques are provided for identifying the servo sectors in a track on a data storage device. A data storage device identifies the servo sectors in a track by reading distributed index bits from multiple servo sectors in a track. The data storage device analyzes only one index bit from each servo sector to identify the index of a track. In some embodiments, the index of a track can be identified after examining the index bits stored in a particular number of consecutive servo sectors, even in the presence of errors. The index bits in each track can have an error tolerance with a minimum Hamming distance greater than one. In other embodiments, a data storage device compares a sliding window of the index bits read from the servo sectors to all possible N-bit vectors that exist within a pattern of the index bits stored on a track.

Abstract: A verifiable security mode is provided for securing data on a storage device, such as a hard disk drive. When the verifiable security mode is enabled, only authenticated accesses to data stored on the storage device are permitted after entering a password. An end user is prevented from disabling the verifiable security mode. The verifiable security mode can be set to allow or disallow an administrator from disabling the verifiable security mode. The verifiable security mode can be implemented, for example, in firmware on a hard disk drive (HDD).

Abstract: Enhancements to the functionality of a file system are provided. A file system can provide an additional level of error correction, in addition to the error correction provided by a data storage device. An extension to the metadata area in a file system can store index information about data files that the file system can use to reduce the time it takes to access the files. A file system can use extended metadata to store conditional access information for data files stored in the file system. A data storage device can also examine and characterize the data being stored in order to categorize a user's files automatically. Modules can be loaded into a file system to provide new functionality to the file system. The modules can load additional modules to extend their functionality.

Abstract: Circuits and methods are provided for write through drivers in disk drive systems. A write through driver is a transceiver that includes a write driver circuit and a receiver circuit. The write driver drives a current signal to a write element through a first conductive interconnect. The write element writes data patterns to a magnetic hard disk in response to the current signal from the write driver circuit. The current signal returns to the receiver circuit through a second conductive interconnect. The return signal can be used for the diagnosis of write-safe conditions.

Abstract: A host operating system (OS) can function as a task under a disk drive operating system. The host OS and the disk drive operating system can be run on a single processor. The processor is able to maintain the real-time response characteristics of a disk drive controller. A shared memory subsystem can be accessed by both operating systems. A disk drive storage device can access and respond to metadata about an underlying file system maintained by a host operating system (OS) to optimize data transfers between the disk drive and the host OS. The disk drive can identify the nature of read/write accesses, allowing it to prioritize and performance optimize the accesses. The disk drive can perform these functions without any changes to the block interface.

Abstract: A magnetoresistive sensor having an in stack bias layer extending beyond the track width of the sensor for improved free layer stability and resistance against amplitude flipping.

Abstract: Magnetic head sliders having air-bearing surfaces designed to reduce the protrusion compensation effect. The magnetic head slider includes: at least one front pad located an upstream portion of the slider and operative to generate a lifting force; and a rear pad that is located downstream of the front pad and includes a load-carrying part, for generating a lifting force, and a head mounting part. The head mounting part is separated from the load-carrying part by a groove formed between the load-carrying part and the head mounting part. The head mounting part contains a heat source that generates heat energy and thereby causes a protrusion throw to form on the slider. The groove suppresses formation of the protrusion throw on the load-carrying part and thereby localizes the protrusion throw mostly in the area adjacent to the head mounting part.

Abstract: A combined encoder/syndrome generator is provided that has a reduced delay. The combined encoder/syndrome generator generates check symbols during an encoding process and error syndromes during a decoding process. The combined encoder/syndrome generator has two or more blocks. The output of each block is fed as an input into a subsequent block. Each block can perform computations in parallel to reduce the delay of the encoding system.

Abstract: Greater error protection is provided to error-prone bits that are generated from irregular soft-decoded error correction codes. Error protection is increased to error-prone bits that of interest in a particular system (e.g., parity check bits). One or more extra bits are added to each codeword in the encoding process. The one or more extra bits correspond to lower weights. The one or more extra bits are discarded after each codeword is decoded.

Abstract: Techniques are provided for reducing error propagation in encoded data using Fibonacci modulation codes. The Fibonacci modulation codes have a Fibonacci base with a variable span that limits error propagation. Some of the elements in the Fibonacci base have a larger span than limited span elements in the base. Errors occurring in bit positions of an encoded sequence that correspond to the limited span elements do not propagate to adjacent bytes in the decoded sequence. The Fibonacci modulation codes can also have a relatively high code rate.