International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Western Digital Technologies, Inc.

Hgst Netherlands, B.v.

Terence Tin-Lok Lam

Zhong-heng Lin

Thomas Young Chang

Changqing Shi

Shanlin Duan

Wai Cheung Leung

Xiaodong Che

Vladimir Nikitin

Wen-Chien David Hsiao

Edward Hin Pong Lee

Weidong Huang

Xiaoyu Sui

Peter Cheng-I Fang

Alex Shteyn

Kuok San Ho

Zhanjie Li

Suping Song

Yaguang Wei

Savas Gider

Edward Hinpong Lee

Quan-chiu Harry Lam

Samuel Wonder Yuan

Donald Giles Allen

Yansheng Luo

Samuel Weisan Yuan

Hieu Lam

David Kaimon Lee

Steve C Puga

Xiangjun Feng

Peter Chen-I Fang

A perpendicular magnetic recording write head includes a main portion formed of conventional high-moment magnetic materials, and a beveled or tapered trailing portion formed of a Co/Fe multilayer with negative magnetic anisotropy (negative anisotropy constant or &#x2014;K). The Co/Fe multilayer tapered trailing portion has a high saturation magnetization (M) and thus functions as part of the write pole to direct the flux perpendicularly to the recording layer. Also, the &#x2014;KCo/Fe multilayer tapered trailing portion has its hard axis oriented substantially orthogonal to the layer thickness and thus substantially prevents flux leakage into the write gap. The &#x2014;KCo/Fe multilayer may also be formed on the sides of the write pole in the cross-track direction to prevent flux leakage into the side gaps.

Magnetic recording write head with write pole having a tapered trailing end section with negative magnetic anisotropy

A write head includes a first pole P1, a P1 pedestal, a first back gap layer plated on top of the first pole P1 leaving a region between the P1 pedestal and the first back gap layer for plating a coil. Further, a first insulation layer is applied on top of the P1 pedestal and the first back gap layer and the region between the P1 pedestal and the first back gap layer. The write head further includes a coil, patterned at least partially on top of the P1 pedestal and the first back gap layer and the region between the P1 pedestal and the first back gap layer, copper plated in the coil patterns, and a second insulation layer is applied to fill the spaces in between the coil turns. The resulting structure is planarized via chemical mechanical polishing.

Self-aligned coil process in magnetic recording heads

A method and apparatus for providing a write head with an improved pole tip to improve overwrite and/or adjacent track interference. A cross pole tip writer is provided with a shape that is designed to reduce the saturation on the pole tip and aid in the concentration of flux to the down track.

Method and apparatus for providing a write head with an improved pole tip to improve overwrite and/or adjacent track interference

A method and apparatus for providing a write head having well-defined, precise write head pole tips. A coplanar write head pole tip processing method provides a thin-film magnetic write head pole tip layer and defines first and second pole tips from the pole tip layer. When the pole tips are provided on a write head, a write gap can be defined using ion milling, E-beam lithography, FAB or can be deposited. The write head pole tips can be used in conjunction with read heads by merging a read head with a write head or a read head can be bonded to a write head in a piggybacked fashion.

Method for making coplanar write head pole tips

Methods and structures for the fabrication of both thin film longitudinal and perpendicular write heads are disclosed. A unique feature of these write heads is the inclusion of layered return poles, which comprise alternating layers of 22/78 and 80/20 NiFe alloys. The alternating layers also vary in thickness, the 22/78 NiFe layers having a nominal thickness of 1500 angstroms and the 80/20 NiFe layers having a nominal thickness of about 75 angstroms. Head efficiency and signal to noise ratios are significantly improved in heads having layered return pole construction.

Layered return poles for magnetic write heads

A magnetic write head having a magnetic cross yoke arranged to provide a cross magnetic field in a pole tip region of the magnetic head. The cross field, which is perpendicular to the magnetization of write pole, reduces the switching time of the write field, thereby increasing the speed with which the write head can record data. The write head can be a longitudinal write head or a perpendicular write head. In the case of a perpendicular write, the write head can include a write pole arranged to provide a magnetic write field that emits a magnetic field substantially perpendicular with an Air Bearing Surface (ABS). A magnetic cross yoke is formed having ends that are disposed at opposite sides of the pole tip region of the write pole.

Write head with self-cross biased pole for high speed magnetic recording

A system and method for determining head-disk contact (HDC) in a magnetic recording disk drive uses the signal from the magnetoresistive (MR) read head. The analog MR signal is digitized and input to a digital signal processor with circuitry and/or software for integrating the signal amplitude over a low-frequency range. The calculated value from the integration when the slider is out-of-contact with the disk is a reference value. The same integration is then performed during operation of the disk drive and the measured value is compared to the reference value. If the measured value exceeds the reference value by some predetermined amount, this is an indication of the onset of HDC or that HDC has occurred. The method can be used in head-disk testers to facilitate the design and testing of disk drive components, such as slider-suspension assemblies and fly-height actuators located on the slider to alter the head-disk spacing, and in disk drives to control fly-height actuators and to take corrective action prior to HDC.

System and method for determining head-disk contact in a magnetic recording disk drive

A system and method for calibrating and controlling a magnetic recording disk drive fly-height actuator uses the signal from the magnetoresistive (MR) read head to determine head-disk contact (HDC). The MR signal is measured over a low-frequency range, with the slider out-of-contact with the disk, to develop a reference value. The MR signal is then measured over the same low-frequency range and if it exceeds the reference value by some predetermined amount, this is an indication of HDC. The fly-height actuator control signal value for HDC is recorded and thus corresponds to a head-disk spacing of zero. The calibration method also determines the sensitivity of head-disk spacing to the fly-height actuator control signal by measuring a series of MR read signal amplitudes for a corresponding series of control signals. The fly-height actuator is calibrated from the sensitivity and the value of control signal that results in zero head-disk spacing, and can then be controlled to move the head to a desired fly height and maintain it at the desired fly height.

System and method for calibrating and controlling a fly-height actuator in a magnetic recording disk drive

A method for measuring a magnetic read width MRW of a magnetic read sensor directly from the derivative of a full track profile, with better accuracy and more advantages than the micro-track method was invented and also there is no need to use a separate wide write head. The magnetic write width MWW of the write head, without the influence of sensor side reading, can also be obtained by this method along with the MRW with no additional calculations.

Full track profile derivative method for read and write width measurements of magnetic recording head

A nonlinear transition shift (NLTS) measurement procedure for read/write heads employing a giant magnetoresistive (GMR) merged heads. The method of this invention includes the pulse-shape distortion effects on recording nonlinearity, which can significantly affect the existing theoretical formulae for calculating nonlinearity correction factor from measured partial erasure values, and second-order approximation of equation of NLTS and nonlinearity correction factor. Transition broadening effects (TBE) and partial erasure (PE) are incorporated in the NLTS measurement procedure to permit accurate isolation of the NLTS from the unrelated TBE/PE and GMR nonlinear transfer characteristic (NTC). First, a fifth harmonic elimination (5HE) test is performed at bit period T to measure a first nonlinearity value X. Then two partial erasure (PE) tests are done at two different densities, one below the PE threshold to measure a second nonlinearity value X and the other at the same density as the 5HE test to measure a third nonlinearity value X . Finally, the NLTS is computed by combining the first, second and third nonlinearity values.

Process for measuring nonlinear transition shift (NLTS) at high recording densities with a giant magetoresistive (GMR) head

A process, computer program product, and apparatus for detecting and quantifying crosstalk instability in a read/write mechanism are provided. A write current is varied in a write circuit for exciting the write head. Measurements are taken of a magnetoresistive impedance of a read current of a read circuit. Measurements are also taken of a signal amplitude in the read circuit. A bit error rate of the overall system is also measured. The read/write mechanism is failed if the signal amplitude changes by a predetermined amount during the varying of the write current. Likewise, the read/write mechanism is failed if the error rate changes by a predetermined amount during the varying of the write current. The write-to-read signal coupling of HGA (Head Gimbal Assembly) and HSA (Head Stack Assembly), including GMR sensor, suspension and flex cable on the actuator arm, can be evaluated at component design level. The methodologies successfully simulate GMR cross talk instability inside a drive on magnetic testers. Therefore, a good prediction of drive failure rate can be achieved.

Cross talk bit error rate testing of a magnetic head

A method of determining a magnetic track width of a magnetic head. The method begins by obtaining a full track profile of the magnetic head which includes a plurality of signal amplitudes read across a track of a magnetic disk at a plurality of magnetic head positions. An initial magnetic track width value is then determined from the full track profile data. Preferably, this initial value is the magnetic write width which is determined based on the difference between left and right head positions which read half of the maximum signal amplitude. To determine the final magnetic write width, the initial value is adjusted with side reading correction values. The side reading correction values are determined based on left and right side reading &ldquo;tails&rdquo; of a bell-shaped signal curve which is formed by the full track profile data when graphed. It is not necessary to obtain the microtrack profile to determine these side reading values. Off track read capability (OTRC) and erase band width (EBW) values determined by the triple track test can also be corrected.

Method and apparatus for determining the magnetic track width of a magnetic head

The magnetic head of the present invention includes a P pole having an opening formed therethrough, and a P pole that is formed over the opening. A second magnetic pole tip is positioned relative to the first magnetic pole such that the first magnetic pole is symmetrically disposed relative to the second magnetic pole tip. Induction coils may be helically wound around portions of the first and/or second magnetic poles, or, alternatively, a planar, spiral induction coil may be fabricated for use with the first and second magnetic poles. An enhanced embodiment includes a first magnetic pole tip piece having a length that defines the throat length of the magnetic head and a thickness that increases the gap at rearward portions of the second magnetic pole tip of the magnetic head.

Magnetic head having write head with double split yoke

The present invention is a read/write head for writing information to magnetic media and reading information from magnetic media. It includes a write head element for writing information onto magnetic media, a read head element for reading information from the magnetic media, and an electromagnetic field shield element that is disposed between the write head element and the read head element. The shield functions to shield the read head from electromagnetic field energy created by the write head element. An enhanced second embodiment includes an electrical circuit element that is disposed proximate the read head element that functions to generate an electromagnetic field at the read head element that is generally oppositely directed to the electromagnetic field generated by the write head element to reduce the total electromagnetic field that the read head element is exposed to during a writing operation. The method for operating the read/write head in a hard disk drive, includes the steps of writing data onto a hard disk and reading data from the hard disk simultaneously with the data writing. This is accomplished by shielding the read head from the electromagnetic field energy generated during the data writing by utilizing the electromagnetic field shield element that is disposed between the write head element and the said read head element. The electrical circuit element of the second embodiment is preferably interconnected with the write head electric circuit.

Magnetic recording transducer with electronic shield

The present invention is a read/write head for writing information to magnetic media and reading information from magnetic media. It includes a write head for writing information onto magnetic media, a read head for reading information from the magnetic media, and an electrical circuit element that is disposed proximate the read head that functions to generate an electromagnetic field at the read head that is generally oppositely directed to the electromagnetic field generated by the write head. The method for operating the read/write head in a hard disk drive, includes the steps of writing data onto a hard disk, while simultaneously generating an electromagnetic field at the read head that is directed oppositely to the electromagnetic field generated by the write head.

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Cupertino, CA, United States of America

Terence Tin-Lok Lam