Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Andreas Klaus Berger

Eric Edward Fullerton

Hoa Van Do

Byron Hassberg Lengsfield, Iii

Natacha Frederique Supper

David Thomas Margulies

Olav Hellwig

Ernesto Esteban Marinero

Kai Tang

Xiaoping Bian

Yoshihiro Ikeda

Kentaro Takano

Mary Frances Minardi

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 patterned perpendicular magnetic recording medium has discrete magnetic islands, each of which has a recording layer (RL) structure that comprises two exchange-coupled ferromagnetic layers. The RL structure may be an 'exchange-spring' RL structure with an upper ferromagnetic layer (MAG), sometimes called the exchange-spring layer (ESL), ferromagnetically coupled to a lower ferromagnetic layer (MAG), sometimes called the media layer (ML). The RL structure may also include a coupling layer (CL) between MAGand MAGthat permits ferromagnetic coupling. The interlayer exchange coupling between MAGand MAGmay be optimized, in part, by adjusting the materials and thickness of the CL. The RL structure may also include a ferromagnetic lateral coupling layer (LCL) that is in contact with at least one of MAGand MAGfor mediating intergranular exchange coupling in the ferromagnetic layer or layers with which it is in contact (MAGor MAG). The ferromagnetic alloy in the LCL has significantly greater intergranular exchange coupling than the ferromagnetic alloy with which it is in contact (MAGor MAG).

Patterned perpendicular magnetic recording medium with exchange coupled recording layer structure and magnetic recording system using the medium

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

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 MAGmay have a coupling layer (CL) located between them that permits ferromagnetic exchange coupling of MAGwith MAG. The LCL is located either above or below MAGand in direct contact with MAGand mediates an effective 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 non-metallic 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 exchange-spring type medium with a lateral coupling layer for increasing intergranular exchange coupling in the lower magnetic layer

A perpendicular magnetic recording medium has an 'exchange-spring' type magnetic recording layer (RL) with an improved coupling layer (CL). The RL includes the first or lower ferromagnetic layer MAG, sometimes called the 'media' layer, the second or upper ferromagnetic layer MAG, sometimes called the &#x201c;exchange-spring&#x201d; layer, and the intermediate CL that provides ferromagnetic exchange coupling between MAGand MAG. The CL is formed of NiCr or RuCr based alloys, or CoCr or CoCrB alloys with high Cr and/or B content (Cr plus B&#x3e;about 25 atomic percent), or RuCoCr alloys with low Co content (&#x3c;about 65 atomic percent). For each CL composition there is a CL thickness range that provides the optimal interlayer exchange coupling between MAGand MAG. The selected CL materials provide an exchange-type perpendicular magnetic recording medium with good magnetic performance, while the relatively high amount of Cr of the CL improves the corrosion resistance of the medium.

Perpendicular magnetic recording medium with exchange-coupled magnetic layers and improved coupling layer

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

A perpendicular magnetic recording system uses an exchange-spring type of perpendicular magnetic recording medium. The medium has a recording layer (RL) that includes a lower media layer (ML) and a multilayer exchange-spring layer (ESL) above the ML. The high anisotropy field (high-H) lower ML and the multilayer ESL are exchange-coupled across a coupling layer. The multilayer ESL has at least two ESLs separated by a coupling layer, with each of the ESLs having an Hsubstantially less than the Hof the ML. The exchange-spring structure with the multilayer ESL takes advantage of the fact that the write field magnitude and write field gradient vary as a function of distance from the write pole. The thicknesses and Hvalues of each of the ESLs can be independently varied to optimize the overall recording performance of the medium.

Perpendicular magnetic recording medium with exchange-spring structure having multiple exchange-spring layers and recording system for the medium

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 perpendicular magnetic recording medium includes a metamagnetic antiferromagnetically-coupled (AFC) layer between the recording layer (RL) and the soft magnetically permeable underlayer (SUL). The metamagnetic AFC layer has essentially no net magnetic moment in the absence of a magnetic field, but is highly ferromagnetic in the presence of a magnetic field above a threshold field. Thus the metamagnetic AFC layer does not contribute to the readback signal during reading, but channels the write field to the SUL during writing because the threshold field is selected to be below the write field. An exchange-break layer EBL is located between the metamagnetic AFC layer and the RL. The metamagnetic AFC layer contains films with a crystalline structure suitable as a growth template for the EBL and RL, so the metamagnetic AFC layer also functions as part of an 'effective EBL', thereby allowing the actual EBL to be made as thin as possible.

Perpendicular magnetic recording medium with metamagnetic antiferromagnetically-coupled layer between the soft underlayer and recording layer

A perpendicular magnetic recording medium, such as a perpendicular magnetic recording disk, has a magnetic 'torque' layer (MTL) that exerts a magnetic torque onto the perpendicular magnetic recording layer (RL) in the presence of the applied perpendicular write field. The MTL thus acts as a write assist layer in reversing the magnetization of the RL. A coupling layer (CL) is located between the MTL and the RL and provides the appropriate ferromagnetic coupling strength between the MTL and the RL.

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Andreas Klaus Berger