Hitachi Global Storage Technologies Netherlands B.v.

Seagate Technology Incorporated

International Business Machines Corporation

Li Tang

Shanlin Duan

Yan Liu

Thomas P Nolan

Zhupei Shi

Youfeng Zheng

Connie C Liu

Bogdan Florin Valcu

Jane Jie Zhang

Jianhua Xue

Tim Minvielle

Kai Tang

Xiaoping Bian

Mary Frances Doerner

Mohammad Taghi Mirzamaani

Hans Juergen Richter

Wai Cheung Leung

Michael Alex

Li-Lien Lee

Tao Zhang

Weilu Hang Xu

James Hammond Brannon

Samuel Dacke Harkness

Shanghsien Alex Rou

Zhong (Stella) Wu

Kai-Chieh Chang

Bob Clyde Robinson

Bradley Frederick Baumgartner

Wen Jiang

Shanghsien S Rou

Ka Chi Wong

Yong-Chang Feng

Provided herein is an apparatus, including a magnetically soft underlayer (SUL); an interlayer stack overlying the SUL, wherein the interlayer stack comprises a seed layer of an fcc material; and a perpendicular magnetic recording layer overlying the interlayer stack, wherein a thickness of the SUL in combination with a distance of the SUL from the perpendicular recording layer is sufficient to orient a total magnetic field corresponding to a magnetic transducer head at an angle of about 45&#xb0;.

Apparatus comprising magnetically soft underlayer

Methods and media structures are provided for increasing writability and reducing unintentional erasure of perpendicular magnetic recording media. Variable permeability is controlled within a thin soft underlayer (SUL) structure, independent of bulk SUL material properties such as magnetic moment (B) and magnetic anisotropy (Hk). Media with an improved combination of easier writability on the recorded track and difficult erasure off-track (between tracks and on neighboring tracks) is achieved, in part, by an unbalanced antiferromagnetically coupled (AFC) SUL structure. A permeability gradient is established within the soft underlayer with layers having different values of permeability and magnetic thickness (Bt). In an aspect, a first SUL layer includes a high permeability region and an overlying low permeability region. A second layer antiferromagnetically couples the first layer to a low permeability third SUL layer. The present invention may be utilized with high density perpendicular recording media requiring carefully balanced magnetic properties.

Antiferromagnetic coupling layers

A perpendicular magnetic recording medium comprises a non-magnetic substrate having a surface; and a plurality of overlying thin film layers forming a layer stack on the substrate surface, the layer stack including a magnetically hard perpendicular magnetic recording layer structure and an underlying soft magnetic underlayer (SUL), the SUL having a thickness of up to about 100 &#x212b;. Also disclosed is a data/information recording, storage, and retrieval system comprising the perpendicular magnetic recording medium and a single-pole magnetic transducer head including main and auxiliary poles positioned in spaced adjacency to an upper surface of the layer stack, the single-pole transducer head comprising a front shield adjacent the main pole.

Perpendicular magnetic recording media with thin soft magnetic underlayers and recording systems comprising same

An apparatus may include a composite soft underlayer and a perpendicular magnetic recording layer overlying the composite soft underlayer. The composite soft underlayer may include a growth template layer, a negative magnetic anisotropy layer overlying the growth template layer, and a magnetically soft layer overlying the negative magnetic anisotropy layer. In some embodiments, the negative magnetic anisotropy layer includes a plurality of grains, and substantially all the grains have negative magnetic anisotropy along an axis substantially perpendicular to a major plane of the composite soft underlayer. In some embodiments, the negative magnetic anisotropy layer includes a thickness of less than or equal to about 3 nm.

Composite soft underlayer including negative anisotropy material

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.

Method and apparatus for quantifying stress and damage in magnetic heads

Spinstand test improvement that measures Functional Byte Error Rate (F-BER) of a disk. The F-BER is correlated to the BER of a disk. The F-BER test is faster than a BER test. The F-BER test is incorporated into a spinstand tester or the software associated with a spinstand tester.

Method and system for testing of magnetic disks using F-BER

A method for determining whether a spike in a read back signal from a read head positioned over a perpendicular recording disk having a magnetically soft underlayer (SUL) is caused by a defect in the SUL or by a thermal asperity (TA). A first read back signal with the spike is obtained in the absence of a local magnetic field near the read head. Then, a permanent magnet or electromagnet is used to induce a small local magnetic field by the read head, and a second signal is obtained. If the signals are substantially similar, a thermal asperity is indicated. Otherwise a defect in the 13 magnetically soft underlayer of the disk is indicated.

System and method for determining whether defect in perpendicular recording disk drive is from thermal asperity or defect in magnetically soft underlayer

A method is provided for testing a magnetoresistive sensor for polarity reversal. In one embodiment, the method includes: writing a test pattern on a magnetic disk; providing a mechanical or thermal stress to the magnetoresistive sensor for a period of time; and, comparing the polarity of the test pattern before and after the application of stress.

Method of detecting polarity reversal in a magnetoresistive sensor

The design of a magnetic thin film disk, for use in a disk drive, with an amorphous or nanocrystalline pre-seed layer preferably followed by a ruthenium-aluminum (RuAl) seed layer is described. The pre-seed layer may be CrTa or AlTi. The pre-seed layer deposited over a glass substrate, for example, allows a more strongly oriented RuAl seed layer to be deposited and, thus, favorably influences the orientation and grain size in the subsequent layers which include preferably at least one Cr alloy underlayer and at least one magnetic layer.

Nonmetallic thin film magnetic recording disk with pre-seed layer

An apparatus and method for detecting and marking delamination defects on thin film disks are disclosed. The apparatus includes a read/write (R/W) head and a burnishing head mounted on separate arms that access the disk while spinning on the test stand. The controller uses the R/W head to perform an initial magnetic test of selected areas on the disk to establish an initial defect map. The burnish head is then flown over the surface for an extended time to accelerate and open up the latent delamination defects by impacting protruding material. The R/W head is then used to perform a second magnetic test which is compared against the first test to identify the delamination defects which have been developed by the burnishing. The delamination defects are then marked with a magnetic pattern which aids in optically locating the defect during subsequent failure analysis.

Thin film delamination detection for magnetic disks

A method and apparatus for precise measurement of pressure dependence of head fly height using transitional thermal signals is disclosed. A slider is positioned relative to a rotating a disk having at least one laser bump. Calibration data is gathered by decreasing the pressure and measuring the fly height until a contact positive TA signal is detected. A non-contact negative TA signal is then normalized using the gathered calibration data. The TA signal amplitude may then be used to ascertain the fly height and pressure for a head.

Method and apparatus for precise measurement of pressure dependence of head fly height using transitional thermal signals

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Fremont, CA, United States of America

Li Tang