News Column

Researchers Submit Patent Application, "Templated Granular Magnetic Recording Media", for Approval

July 8, 2014



By a News Reporter-Staff News Editor at Life Science Weekly -- From Washington, D.C., NewsRx journalists report that a patent application by the inventors Grobis, Michael Konrad (San Jose, CA); Schabes, Manfred E. (Saratoga, CA), filed on December 19, 2012, was made available online on June 26, 2014 (see also Hgst Netherlands B.v.).

The patent's assignee is Hgst Netherlands B.v.

News editors obtained the following quote from the background information supplied by the inventors: "A key component of most computers is an assembly that is referred to as a magnetic disk drive, or hard disk drive. The magnetic disk drive includes a rotating magnetic disk, write and read heads that are suspended by a suspension arm adjacent to a surface of the rotating magnetic disk and an actuator that swings the suspension arm to place the read and write heads over selected circular tracks on the rotating disk. The read and write heads are directly located on a slider that has an air bearing surface (ABS). When the slider rides on the air bearing, the write and read heads are employed for writing magnetic impressions to and reading magnetic impressions from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.

"Perpendicular magnetic recording, wherein the recorded bits are stored in a perpendicular or out-of plane orientation in the recording layer, is a promising path toward ultra-high recording densities in magnetic recording hard disk drives. One type of perpendicular magnetic recording system is a system that uses a dual layer media. The dual layer media includes a perpendicular magnetic data recording layer formed on a soft or relatively low coercivity magnetically permeable under-layer. The under-layer serves as a flux return path for the field from the write pole to the return pole of the recording head. The magnetic transitions between adjacent oppositely direct magnetized regions are detectable by the read element or head as the recorded bits.

"Other variations of granular media have been explored for use in magnetic data recording systems as well. For example, granular media that can be used with thermally assisted writing, and microwave assisted writing. Media for thermally assisted recording (TAR) may include granular materials like CoPtCr, FePt, CoPt and other alloys. Media for microwave assisted writing may include granular materials like CoPtCr, FePt, CoPt and other alloys.

"One type of material that can be used as a recording layer is a granular ferromagnetic cobalt (Co) alloy, such as a CoPtCr alloy, with a hexagonal-close-packed (HCP) crystalline structure having the c-axis oriented substantially out of plane or perpendicular to the plane of the recording layer. The granular cobalt alloy recording layer should also have a well-isolated fine-grain structure to produce a high coercivity (Hc) media and to reduce inter-granular exchange coupling, which is responsible for high intrinsic media noise. Enhancement of the grain segregation in the cobalt alloy recording layer can be achieved by the addition of oxides, including oxides of Si, Ta, Ti and Nb. These oxides tend to precipitate to the grain boundaries, and together with the elements of the cobalt alloy, form a non-magnetic inter-granular material.

"The Co alloy recording layer has substantially out of plane or perpendicular magnetic anisotropy as a result of the c-axis of its HCP crystalline structure being induced to grow substantially perpendicular to the plane of the layer during deposition. To induce this growth of the HCP recording layer, the inter-layer onto which the recording layer is formed is also an HCP material. Ruthenium (Ru) and certain Ru alloys, such as RuCr, are non-magnetic HCP materials that can be used for the inter-layer.

"The enhancement of segregation of the magnetic grains in the recording layer by the additive oxides is important for achieving high areal density and recording performance. The inter-granular oxide material not only decouples inter-granular exchange, but also exerts control on the size and distribution of the magnetic grains in the recording layer. Current disk fabrication methods achieve this segregated recording layer by growing the recording layer on a Ru or Ru-alloy interlayer that exhibits columnar growth of the Ru or Ru alloy grains. The columnar growth of the interlayer is accomplished by sputter depositing it at a relatively high sputtering pressure.

"However, such a process results in a recording layer having a relatively wide variation in the size of the magnetic grains. A large grain size distribution is undesirable because it results in a variation in magnetic recording properties across the disk and because some of the smaller grains can become thermally unstable, resulting in a loss of data. There is, therefore, a need for a magnetic media having uniform grain structure, and also for a recording system that can effectively record to such a recording medium without excessive signal noise or bit error rate."

As a supplement to the background information on this patent application, NewsRx correspondents also obtained the inventors' summary information for this patent application: "The present invention provides a method for magnetic data recording to a magnetic media configured for perpendicular magnetic data recording and having an ordered granular structure. The method includes writing an un-synchronized bootstrap servo to the magnetic media, and creating a frequency map and a phase map. A synchronized servo is then recorded to the media and the frequency map and phase map are refined.

"The method can be embodied in a magnetic data recording system that includes circuitry for synchronizing the write frequency and phase to the ordered granular structure of the media.

"The invention advantageously allows full advantage to be taken of a well ordered grain structure in a magnetic media, which may be a templated magnetic media having various zones each with an ordered granular structure.

"The invention can be implemented in a system wherein the magnetic media has a lattice with one or more lattice vectors and wherein the grain lattice is ordered so that one of the one or more lattice vectors is kept parallel to a constant field contour of a trailing edge of a write pole of the write head and is appropriately rotated to account for skew of the write head.

"In addition, the invention can be implemented in a data recording system wherein the system is configured for one or more of thermally assisted magnetic recording, microwave assisted recording and shingled magnetic recording.

"In addition, the invention can be implemented in a system having electronics configured to synchronize the write frequency and write phase in a down-track direction, but not in a cross-track direction.

"These and other features and advantages of the invention will be apparent upon reading of the following detailed description of preferred embodiments taken in conjunction with the Figures in which like reference numerals indicate like elements throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

"For a filler understanding of the nature and advantages of this invention, as well as the preferred mode of use, reference should be made to the following detailed description read in conjunction with the accompanying drawings which are not to scale.

"FIG. 1 is a schematic illustration of a disk drive system in which the invention might be embodied;

"FIG. 2 is an enlarged, cross sectional view of a portion of a magnetic media according to an embodiment of the invention;

"FIG. 3 is an enlarged top down view of a portion of a magnetic media having ordered grains and without write synchronization;

"FIG. 4a is an enlarged top down view of a portion of a magnetic media having ordered grains with write synchronization with a head traveling without skew;

"FIG. 4b is an enlarged top down view of a portion of a magnetic media having ordered grains with write synchronization with a head traveling with skew

"FIG. 5 is a top down view of a magnetic media showing an orientation of magnetic grain structure as affected by skew angle of a magnetic recording head over the surface of the media;

"FIG. 6 is a top down view of a magnetic media showing an arrangement of zones according to an embodiment of the invention;

"FIG. 7 is a top down view of a magnetic media showing an arrangement of zones according to an alternate embodiment of the invention;

"FIG. 8 is a flow chart illustrating a method according to an embodiment of the invention;

"FIG. 9 is a flow chart illustrating a method according to an alternate embodiment of the invention;

"FIG. 10 is a flow chart illustrating a method according to yet another embodiment of the invention; and

"FIG. 11 is a flow chart illustrating a method according to still another embodiment of the invention;

"FIG. 12 is a schematic, top-down view of a magnetic media illustrating an offset between data tracks and zones;

"FIG. 13 is a graph of lattice frequency vs. rotational angle; and

"FIG. 14 is a schematic, top-down view of a magnetic media illustrating various parameters playing a part in determining an ideal frequency F and phase P."

For additional information on this patent application, see: Grobis, Michael Konrad; Schabes, Manfred E. Templated Granular Magnetic Recording Media. Filed December 19, 2012 and posted June 26, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4991&p=100&f=G&l=50&d=PG01&S1=20140619.PD.&OS=PD/20140619&RS=PD/20140619

Keywords for this news article include: Anions, Oxides, Oxygen Compounds, Transition Elements, Hgst Netherlands B.v..

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Life Science Weekly


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