Fujitsu Corporation

Seagate Technology Incorporated

Maxtor Corporation

E Noel Abarra

B Ramamurthy Acharya

Iwao Okamoto

Yoshifumi Mizoshita

Akihiro Inomata

Gunn Choe

Antony Ajan

Jianing Zhou

Min Zheng

Michael L Mallary

Yuki Yoshida

Isatake Kaitsu

Hisashi Umeda

Hisateru Sato

Albert Tchekanov

Robert Weng

Paramjit Gill

A perpendicular recording medium having a perpendicular magnetic recording layer and a magnetically soft underlayer structure disposed beneath the recording layer. The soft underlayer structure includes at least first and second soft magnetic layers having different magnetic permeabilities to create a magnetic permeability gradient in the soft underlayer structure. One or more of the soft magnetic layers can be antiparallel coupled. The soft underlayer structure of the present invention having a magnetic permeability gradient advantageously leads to reduced adjacent track erasure (ATE) while maintaining good overwrite (OW) properties.

Magnetic recording medium for perpendicular magnetic recording

A perpendicular recording medium having a perpendicular magnetic recording layer and a magnetically soft underlayer structure disposed beneath the recording layer. The soft underlayer structure includes at least first and second soft magnetic layers having different magnetic permeabilities to create a magnetic permeability gradient in the soft underlayer structure. One or more of the soft magnetic layers can be anti-parallel coupled. The soft underlayer structure of the present invention having a magnetic permeability gradient advantageously leads to reduced adjacent track erasure (ATE) while maintaining good overwrite (OW) properties.

Perpendicular magnetic recording media having a magnetic capping layer that is exchange coupled to an underlying perpendicular magnetic recording layer. The magnetic coupling layer is a granular layer having a high saturation magnetization (M). The perpendicular magnetic recording layer can include magnetic grains separated by an oxide grain boundary phase.

Media for high density perpendicular magnetic recording

A system for reducing spike noise in a perpendicular recording medium having a soft underlayer is provided. The system radially biases the soft underlayer to substantially eliminate domain walls therein. In a first embodiment of the system, a permanent magnetic bias ring is disposed generally adjacent to the soft underlayer and a magnetic circuit is formed between the magnetic ring and the soft underlayer. Other embodiments include a concentric stationary magnetic flux return disk to extend the radial distance of the flux path. In alternative embodiments, a ferromagnetic spindle assembly is modified to produce a radiation pattern that has a net radial exterior field that biases the adjacent soft underlayer of the medium. The entire assembly can be shielded from external magnetic fields in the disk drive. Further, the shielding may operate as part of the magnetic circuit.

Method and apparatus for eliminating spike noise in a soft magnetic underlayer

A magnetic recording medium and a magnetic recording apparatus for perpendicular magnetic recording. The recording medium includes a magnetically soft underlayer and a hard magnetic pinning layer having perpendicular anisotropy. The magnetically soft underlayer is substantially free of domain walls.

Perpendicular magnetic recording medium with a pinned soft underlayer

A magnetic recording medium is provided with an hcp Co alloy magnetic layer with the crystallographic c-axes tilted at an angle from a substrate surface and fixed relative to a recording direction. The tilt is induced by epitaxial growth of the hcp Co alloy on an obliquely evaporated nonmagnetic polycrystalline underlayer, so that the magnetic recording medium exhibits thermal stability and improved overwrite with a single pole-type head.

Magnetic recording medium, magnetic storage apparatus and method of producing magnetic recording medium

A magnetic recording medium is provided with a substrate, a recording magnetic layer made of a CoCr alloy and having a (110) crystallographic texture, and an underlayer, made of an AlV or AlRuV alloy, disposed between the substrate and the magnetic layer.

Magnetic recording medium and magnetic storage apparatus

A magnetic recording medium includes a substrate, a magnetic recording layer made of a Co alloy or a CoCr alloy, a seed layer disposed between the substrate and the magnetic recording layer, and an underlayer made of a binary alloy material having a B2 structure and disposed between the seed layer and the magnetic recording layer. The seed layer is made of a material comprising essentially of one of elements forming the binary alloy material of the underlayer.

A magnetic recording medium includes a nonmagnetic underlayer, an initial magnetic layer, a nonmagnetic spacer layer provided on the initial magnetic layer, and a final magnetic layer provided on the nonmagnetic spacer layer. The initial magnetic layer is disposed closer to the nonmagnetic underlayer than the final magnetic layer, and the initial and final magnetic layers are made of mutually different compositions and are anti-ferromagnetically coupled.

Magnetic recording medium with anti-ferromagnetically coupled magnetic layers, and magnetic storage apparatus

A magnetic recording medium is constructed to include a substrate, a magnetic layer made of a Co or Co-based alloy, and an underlayer disposed between the substrate and the magnetic layer. The underlayer is made of an ordered intermetallic material of FCC L1 or FCT L1 crystalline structure, so that c-axis of the magnetic layer is aligned in a predetermined direction.

A magnetic recording medium is constructed to include at least one exchange layer structure, and a magnetic layer formed on the exchange layer structure, where the exchange layer structure comprises a ferromagnetic layer, and a non-magnetic coupling layer provided on the ferromagnetic layer and under the magnetic layer. The ferromagnetic layer and the magnetic layer have antiparallel magnetizations. The non-magnetic coupling layer is made of a Ru-M3 alloy, where M3 is an added element or alloy, and a lattice mismatch between the non-magnetic coupling layer and the magnetic layer and the ferromagnetic layer respectively disposed above and below the non-magnetic coupling layer is adjusted to approximately 6% or less by addition of M3.

A magnetic storage medium includes first and second magnetic layers provided on a support substrate such that the first and second magnetic layers have respective first and second magnetizations in an anti-parallel relationship in a state no substantial writing magnetic field is applied. The first and second magnetizations are changed to a parallel relationship when a writing magnetic field is applied to the magnetic storage medium, and the first and second magnetizations are changed to the anti-parallel relationship as a result of a magnetic reversal caused in the second magnetic layer with diminishing of the writing magnetic field. The reversal is caused as a result of the action of a reversing magnetic field that dominates before the writing magnetic field is diminished and becomes zero.

Magnetic storage medium having improved thermal stability and a magnetic storage device using such a high-density magnetic storage medium

A magnetic recording medium is provided with at least one exchange layer structure, and a magnetic layer formed on the exchange layer structure. The exchange layer structure includes a ferromagnetic layer and a non-magnetic coupling layer provided on the ferromagnetic layer and under the magnetic layer.

Magnetic recording medium, magnetic storage apparatus, recording method and method of producing magnetic recording medium

A magnetic recording medium is constructed to include at least one exchange layer structure and a magnetic layer provided on the exchange layer structure. The exchange layer structure includes a ferromagnetic layer and a non-magnetic coupling layer provided on the ferromagnetic layer. At least one of the ferromagnetic layer and the magnetic layer has a granular layer structure in which ferromagnetic crystal grains are uniformly distributed within a non-magnetic base material.

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Kawasaki, Japan

E Noel Abarra