Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Natacha Frederique Supper

Hoa Van Do

Eric Edward Fullerton

David Thomas Margulies

Andreas Klaus Berger

Hal Jervis Rosen

Yoshihiro Ikeda

Byron Hassberg Lengsfield, Iii

Brian Rodrick York

Ernesto Esteban Marinero

Bruce David Terris

Qing Dai

Xiaoping Bian

Mary Frances Doerner

Andreas Moser

Kentaro Takano

Qi-Fan Xiao

Mary Frances Minardi

Manfred Albrecht

Min Xiao

A laminated magnetic recording structure for use in perpendicular or longitudinal recording is described. A small amount of ferromagnetic coupling is added between the two magnetic layers that are sufficiently decoupled to switch independently. In one embodiment the coupling is achieved by doping the spacer layer with a ferromagnetic material. Ruthenium (Ru), which is a preferred nonmagnetic material for spacer layers with cobalt (Co) being the preferred magnetic material. The weak ferromagnetic coupling can also be achieved through the use of platinum, palladium and alloys thereof for the spacer layer without the addition of a ferromagnetic element, but alternatively they can also be doped with ferromagnetic elements. For embodiments for perpendicular recording the spacer layer further can additionally comprise oxides of one or more elements selected from the group consisting of Si, Ta, Ti, Nb, Cr, V and B.

Laminated magnetic thin films for magnetic recording with weak ferromagnetic coupling

A recording medium providing improved writeability in perpendicular recording applications includes a magnetic recording layer having an axis of magnetic anisotropy substantially perpendicular to the surface thereof, an exchange-spring layer ferromagnetically exchange coupled to the magnetic recording layer and having a coercivity less than the magnetic recording layer coercivity, and a coupling layer between the magnetic recording layer and the exchange-spring layer. The coupling layer regulates the ferromagnetic exchange coupling between the magnetic recording layer and the exchange-spring layer.

Perpendicular recording media having an exchange-spring structure

The invention includes a disk drive with a magnetic recording disk with an upper and lower sublayer in at least one magnetic layer of a laminated magnetic layer structure that includes a spacer layer that substantially decouples the magnetic layers. The lower sublayer has a lower boron content than the upper sublayer and a preferred embodiment is CoPtCrBTa. The upper sublayer is deposited onto the lower sublayer and is preferably CoPtCrB with a higher boron content than the lower sublayer. The composition of the lower sublayer gives it a very low moment with low intrinsic coercivity which would not be useful as a recording layer on its own. The upper sublayer is a higher moment alloy with high intrinsic coercivity. An embodiment of the invention includes a laminated magnetic layer structure which is antiferromagnetically coupled to a lower ferromagnetic layer.

Disk drive with laminated magnetic thin films with sublayers for magnetic recording

An improved structure for the construction of perpendicular recording media is disclosed. The structure includes a perpendicular recording layer with at least two oxide sublayers or a lower sublayer of a non-oxide. One structure includes an upper sublayer comprised of a Silicon-oxide, while a lower sublayer is comprised of a Tantalum-oxide. The structures provide for increased coercivity and corrosion resistance.

Oxide magnetic recording layers for perpendicular recording media

An improved structure for the construction of perpendicular recording media is disclosed. The structure includes a tri-layer IML resident between a soft under layer CoTaZr film and a CoPtCr&#x2014;SiOmagnetic media. In an embodiment, the tri-layer comprises a RuCrlayer over dual nucleation layers of Ni&#x2014;Fe and Ni&#x2014;Fe&#x2014;Cr. The tri-layer replaces the typical Ru and Ni&#x2014;Fe intermediate layers of the prior art, resulting in considerable improvement in lattice matching between the Ru containing intermediate layer and the CoPtCr&#x2014;SiOmagnetic media, further resulting in improved magnetic media performance.

Intermediate tri-layer structure for perpendicular recording media

An apparatus and method is disclosed for orienting the magnetic anisotropy of longitudinal patterned magnetic recording media. A disk-shaped longitudinal granular magnetic recording medium is provided having a high orientation ratio in the circumferential direction. The medium is then patterned to form a uniform array of magnetic islands. The magnetic islands are then irradiated with ions to increase the magnetic exchange coupling between the grains of each island. This aligns the axes of magnetic anisotropy of the individual grains with the average axis of magnetic anisotropy of the grains, thereby aligning the magnetic anisotropy of each island along the circumferential direction.

Longitudinal patterned media with circumferential anisotropy for ultra-high density magnetic recording

A perpendicular magnetic recording system and medium has a multilayered recording layer that includes an exchange-spring structure and a ferromagnetic lateral coupling layer (LCL). The exchange-spring structure is made up of two ferromagnetically exchange-coupled magnetic layers (MAGand MAG), each with perpendicular magnetic anisotropy. MAGand MAGare either in direct contact with one another or have a coupling layer (CL) located between them. The LCL is located in direct contact with MAGand mediates intergranular exchange coupling in MAG. The ferromagnetic alloy in the LCL has significantly greater intergranular exchange coupling than the ferromagnetic alloy in MAG, which typically will include segregants such as oxides. The LCL is preferably free of oxides or other segregants, which would tend to reduce intergranular exchange coupling in the LCL. Because the LCL grain boundaries overlay the boundaries of the generally segregated and decoupled grains of MAG, and the LCL and MAGgrains are strongly coupled perpendicularly, the LCL introduces an effective intergranular exchange coupling in the MAG

Perpendicular magnetic recording medium with an exchange-spring recording structure and a lateral coupling layer for increasing intergranular exchange coupling

An embodiment of the invention is a layered magnetic thin film structure that uses antiferromagnetically coupled (AFC) magnetic layers where the top layer structure consists of an upper magnetic layer that is weakly ferromagnetically coupled via a nonmagnetic or weakly magnetic exchange coupling layer (interlayer) to a ferromagnetic exchange enhancing layer that is in turn, AF coupled to the lower ferromagnetic layer of the AFC structure. Preferred materials for the weak coupling layer include alloys of cobalt such as CoRu, CoBRu and CoCr in which the Co content is below the point at which the material would be ferromagnetic. A second embodiment of the invention is a laminated, AF-coupled media structure. In this structure the lower AFC layer that makes up the lower laminate layer includes: the middle magnetic layer, the weak ferromagnetic coupling layer, and the exchange enhancing layer.

Antiferromagnetically coupled media for magnetic recording with weak coupling layer

A perpendicular magnetic recording medium has an 'exchange-spring' type magnetic recording layer (RL) formed of two ferromagnetic layers with substantially similar anisotropy fields that are ferromagnetically exchange-coupled by a nonmagnetic or weakly ferromagnetic coupling layer. Because the write head produces a larger magnetic field and larger field gradient at the upper portion of the RL, while the field strength decreases further inside the RL, the upper ferromagnetic layer can have a high anisotropy field. The high field and field gradient near the top of the RL, where the upper ferromagnetic layer is located, reverses the magnetization of the upper ferromagnetic layer, which then assists in the magnetization reversal of the lower ferromagnetic layer. Because both ferromagnetic layers in this exchange-spring type RL have a high anisotropy field, the thermal stability of the medium is not compromised. The medium shows improved writability, i.e., a low switching field, as well as lower intrinsic media noise, over a medium with a conventional single-layer RL.

Perpendicular magnetic recording medium with multiple exchange-coupled magnetic layers having substantially similar anisotropy fields

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 method and apparatus for improving the signal-to-noise ratio in a longitudinal recording media is disclosed. The apparatus includes a first recording layer of the longitudinal recording media residing at the top of a recording media structure. The first recording layer includes an upper sublayer comprised of a CoPtCrB-based alloy material. The first recording layer also includes a lower sublayer comprised of a CoPtCrB-based alloy material and a middle sublayer comprised of a CoCrB-alloy. The middle sublayer is coupled to the upper sublayer and to the lower sublayer and is substantially thinner than the upper sublayer and the lower sublayer.

Method and apparatus for improving signal-to-noise ratio in longitudinal recording media

A laminate structure is disclosed comprising multiple ferromagnetic layers achieving incoherent reversal while maintaining good SNR. A high magnetic moment density, low anisotropy field material may form a thin overlayer deposited over a high-anisotropy media layer. The media layer may have a lower magnetic moment density than the overlayer and have decoupled magnetic grains. A coupling layer may be interposed between the overlayer and the media layer to modulate the exchange there between, thereby reducing the pass-through of noise while still promoting incoherent reversal to achieve reduced write energy requirements.

Incoherently-reversing magnetic laminate with 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.

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Campbell, CA, United States of America

Natacha Frederique Supper