International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Hal Jervis Rosen

Kurt A Rubin

Timothy Carl Strand

Wayne Isami Imaino

Milton Russell Latta

Anthony Juliana

Wai Cheung Leung

Margaret E Best

David Thomas Margulies

Charles H Lee

Eric Edward Fullerton

Andreas Moser

Bruce David Terris

Hoa Van Do

Robert Fontana

Barry C Stipe

Ching Hwa Tsang

Ernesto Esteban Marinero

Natacha Frederique Supper

Petrus Antonius VanDerHeijden

Wade Wai-Chung Tang

Wade W-c Tang

Thomas R Albrecht

Bruce Alvin Gurney

Matthew Joseph Carey

Steven W Meeks

Brian Rodrick York

Michael Grobis

Jan-Ulrich Thiele

Manfred Ernst Schabes

James Hammond Brannon

Jia-Yang Juang

Terry W McDaniel

Richard Sonningfeld

Charles Chung Lee

Stefan Maat

Nimrod Megiddo

James M Zavislan

Thomas Guthrie Zimmerman

Fu-Ying Huang

Ricardo Ruiz

Sridhar Rajagopalan

James Terrence Olson

Alan A Fennema

Glenn T Sincerbox

Linden James Crawforth

Blair I Finkelstein

Ronald Fagin

Andrew A Gaudet

Gregory John Parker

Robert John Tasman Morris

Virat Vasav Mehta

Harris Anthony Notarys

Victor T Pan

A heat-assisted magnetic recording (HAMR) disk has multiple independent data layers, each data layer being a continuous non-patterned layer of magnetizable material. Each data layer can store data independent and not related to the data stored in the other data layers. The data layers are separated by a nonmagnetic spacer layer (SL) and each data layer is formed of high-anisotropy (K) material so that the coercivities of lower and upper data layers (RL1 and RL2) are greater than the magnetic write field. At a high laser power both RL1 and RL2 are heated to above their respective Curie temperatures and data is recorded in both RL1 and RL2. At low laser power only upper RL2 is heated to above its Curie temperature and data is recorded only in RL2. The SL prevents lower RL1 from being heated to above its Curie temperature at low laser power.

Heat-assisted magnetic recording (HAMR) disk with multiple continuous magnetic recording layers

A thermally-assisted recording (TAR) disk drive uses 'shingled' recording and a rectangular waveguide as a 'wide-area' heat source. The waveguide generates a generally elliptically-shaped optical spot that heats an area of the recording layer extending across multiple data tracks. The waveguide core has an aspect ratio (cross-track width to along-the track thickness) that achieves the desired size of the heated area while locating the peak optical intensity close to the trailing edge of the write pole tip where writing occurs. The large cross-track width of the waveguide core increases the volume of recording layer heated by the optical spot, which reduces the rate of cooling. This moves the peak temperature point of the heated area closer to the write pole tip and reduces the temperature drop between the peak temperature and the temperature at the trailing edge of the write pole tip where writing occurs.

Magnetic recording disk drive with shingled writing and rectangular optical waveguide for wide-area thermal assistance

A thermally-assisted recording (TAR) disk drive that uses 'shingled' recording and a rectangular waveguide as a 'wide-area' heat source includes a controller that counts the number of writes to each annular band of data tracks. The wide-area heater generates a heat spot that extends across multiple tracks, so that each time an annular band is written, the data in tracks in adjacent bands are also heated. Because the bands are written independently, the number of passes of the heat spot and thereby the number of times the data tracks in a band are exposed to elevated temperatures without being re-written is related to the number of re-writes of the adjacent bands. The number of writes to each band is counted and when that count reaches a predetermined threshold value, one or more tracks in an adjacent band are re-written to avoid reaching an unacceptable level of magnetization decay in the tracks of the adjacent band.

Shingled-writing thermal assistance recording (TAR) disk drive with avoidance of adjacent track erasure from a wide-area heater

A thermally-assisted recording (TAR) disk drive uses a 'wide-area' heater with 'shingled' recording. In shingled recording, the write head pole tip is wider than the read head in the cross-track direction and writes magnetic transitions by making a plurality of consecutive circular paths that partially overlap. The non-overlapped portions of adjacent paths form the data tracks, which are thus narrower than the width of the write pole tip. The data tracks are grouped into annular bands and when data is to be rewritten, all of the data tracks in an annular band are also rewritten. The wide-area heater may be a waveguide with an output end that generates a heated area on the disk recording layer which is wider than the cross-track width of the write pole tip. It has been determined that the use of a wide-area heater with shingled recording does not result in any significant adjacent track erasure (ATE).

Magnetic recording disk drive with shingled writing and wide-area thermal assistance

A magnetoresistive (MR) sensor or read head for a magnetic recording disk drive has multiple independent current-perpendicular-to-the-plane (CPP) MR sensing elements. The sensing elements are spaced-apart in the cross-track direction and separated by an insulating separation region so as to be capable of reading data from multiple data tracks on the disk. The sensing elements have independent CPP sense currents, each of which is directed to independent data detection electronics, respectively. Each sensing element comprises a stack of layers formed on a common electrically conducting base layer, which may be a bottom magnetic shield layer formed of electrically conducting magnetically permeable material. Each sensing element has a top electrical lead layer. A top magnetic shield layer is located above the sensing elements in contact with the top lead layers. The top shield layer is formed of soft magnetically permeable material, but is electrically insulating, so that the independent sense currents can be passed to the independent sensing elements.

Current-perpendicular-to-the-plane (CPP) magnetoresistive read head with multiple sensing elements for patterned-media

A continuous-media perpendicular magnetic recording disk with an oxide-containing granular Co alloy recording layer (RL) having minimal grain size dispersion has an ordered nucleation layer (ONL) formed below RL. The ONL has ordered nucleation sites arranged in a generally repetitive pattern. The nucleation sites are generally surrounded by non-nucleation regions of a different material than the nucleation sites. The Co-alloy grains of the subsequently deposited RL grow on the nucleation sites and the oxide of the RL become generally segregated on the non-nucleation regions. The ordered nucleation sites may be formed of a Ru-containing material and the non-nucleation regions may be formed of an oxide. The ONL is formed by nanoimprint lithography, preferably by a master mold fabricated with a method using self-assembling block copolymers for creating periodic nanometer scale features.

Perpendicular magnetic recording disk with ordered nucleation layer and method for making the disk

Magnetic memories and methods are disclosed. A magnetic memory as described herein includes a plurality of stacked data storage layers to form a three-dimensional magnetic memory. Bits may be written to a data storage layer in the form of magnetic domains. The bits can then be transferred between the stacked data storage layers by heating a neighboring data storage layer, which allows the magnetic fields from the magnetic domains to imprint the magnetic domains in the neighboring data storage layer. By imprinting the magnetic domains into the neighboring data storage layer, the bits are copied from one data storage layer to another.

Three-dimensional magnetic memory

A hard disk drive (HDD) has a stack of disks mounted on a rotatable spindle with the disks being movable axially, i.e., in a direction parallel to the axis of rotation of the spindle. A disk separator is located inside the spindle and separates axially-adjacent disks in a pair to create an axial gap. Any pair of axially-adjacent disks can be separated so that different axial gaps are created. A single head-arm assembly with at least one and preferably two read write heads is movable axially so that it can be rotated by the rotary actuator into any one of the axial gaps. The read/write heads can thus access data on the disk surfaces in the axial gaps. When it is desired to have the disk separator create an new axial gap and thus a new pair of disk surfaces to be accessed, the actuator rotates the head-arm assembly away from the outer perimeters of the disks and moves the read/write heads onto a head support structure that supports the read/write heads off the disks.

Hard disk drive with disk separator for creating axial gaps between disks for access by read/write heads

Three-dimensional magnetic memory having bits transferrable between storage layers

A laminated perpendicular magnetic recording medium has two recording layers (RLand RL) that are separated and magnetically decoupled by a nonmagnetic spacer layer (SL). The SL has a thickness and composition to assure there is no antiferromagnetic or ferromagnetic coupling between RLand RL. Thus in the presence of the write field, RLand RLrespond independently and become oriented with the direction of the write field. Each RL is an 'exchange-spring' type magnetic recording layer formed of two ferromagnetic layers (MAGand MAG) that have substantially perpendicular magnetic anisotropy and are ferromagnetically exchange-coupled by a nonmagnetic or weakly ferromagnetic coupling layer (CL). The medium takes advantage of lamination to attain higher signal-to-noise ratio (SNR) yet has improved writability as a result of each RL being an exchange-spring type RL.

Perpendicular magnetic recording medium with laminated recording layers formed of exchange-coupled ferromagnetic layers

A magnetic recording medium has a laminated magnetic structure with at least three magnetic layers, wherein the magnetic layers have decreasing intrinsic coercivity Hwith distance from the write head. The write field at the center of each magnetic layer is greater than that layer's H. The magnetic layers have different compositions and/or thicknesses and thereby different values of H. The alloys used in the middle and upper magnetic layers are relatively 'high-moment' alloys that would not ordinarily be used in magnetic recording media because they have relatively low SNR, but the overall SNR of the laminated magnetic structure is improved because of the effect of lamination. The middle and upper magnetic layers can be made substantially thinner, which enables the magnetic layers to be located closer to the write head, thereby exposing each of the magnetic layers to a higher write field.

Magnetic recording medium having three ferromagnetic layers with increasing intrinsic coercivity from the lower to the upper layer

A magnetic recording system uses a magnetic recording medium having a laminated magnetic structure with at least three magnetic layers, wherein the magnetic layers have decreasing intrinsic coercivity Hwith distance from the write head. The write field at the center of each magnetic layer is greater than that layer's H. The magnetic layers have different compositions and/or thicknesses and thereby different values of H. The alloys used in the middle and upper magnetic layers are relatively 'high-moment' alloys that would not ordinarily be used in magnetic recording media because they have relatively low SNR, but the overall SNR of the laminated magnetic structure is improved because of the effect of lamination. The middle and upper magnetic layers can be made substantially thinner, which enables the magnetic layers to be located closer to the write head, thereby exposing each of the magnetic layers to a higher write field.

Magnetic recording system with three-layer laminated media having improved signal-to-noise ratio

A magnetic recording disk drive has an inductive write head and a heater to record data in laminated media on the recording disk. The laminated media, with at least two ferromagnetic layers separated by a nonmagnetic spacer layer, improves SNR. Each of the ferromagnetic layers can be formed of a material having an intrinsic coercivity capable of being written by a conventional inductive write head, but because of the desired lamination to increase SNR, the ferromagnetic layer farthest from the write head is exposed to a magnetic field less than its intrinsic coercivity and thus can not be written. To write to the laminated media, heat is directed to the lower ferromagnetic layer to reduce its intrinsic coercivity below the magnetic field to which it is exposed.

Magnetic recording disk drive with laminated media and improved media signal-to-noise ratio

Method for magnetic recording on laminated media with improved media signal-to-noise ratio

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Los Gatos, CA, United States of America

Hal Jervis Rosen