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    Magnetic recording medium and magnetic storage apparatus
    2.
    发明授权
    Magnetic recording medium and magnetic storage apparatus 有权

    公开(公告)号：US11302349B2

    公开(公告)日：2022-04-12

    申请号：US17325347

    申请日：2021-05-20

    Applicant: SHOWA DENKO K.K.

    Inventor： Kota Hasegawa ,  Takayuki Fukushima

    IPC: G11B5/65 ,  G11B5/02 ,  G11B5/73

    Abstract: A magnetic recording medium includes a substrate, an underlayer disposed above the substrate, and a first magnetic layer disposed above the underlayer. The first magnetic layer has a granular structure including magnetic grains having a L10 structure, and grain boundaries. A content of the grain boundaries is in a range of 25 volume percent to 50 volume percent, and the grain boundaries include a chalcogenide-based layered material.

    Magnetic recording medium having magnetic layer with hydride of carbon, and magnetic storage apparatus
    3.
    发明授权
    Magnetic recording medium having magnetic layer with hydride of carbon, and magnetic storage apparatus 有权

    公开(公告)号：US10984829B2

    公开(公告)日：2021-04-20

    申请号：US16279143

    申请日：2019-02-19

    Applicant: SHOWA DENKO K.K.

    Inventor： Kota Hasegawa ,  Katsuaki To

    IPC: G11B5/667 ,  G11B5/65 ,  G11B5/66 ,  C23C16/28 ,  C22C19/07 ,  C23C16/505

    Abstract: A magnetic recording medium includes a nonmagnetic substrate, a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic layer, and a protection layer that are arranged in this order. The perpendicular magnetic layer includes a first magnetic layer and a second magnetic layer that are arranged in this order on the orientation control layer. The first magnetic layer has a granular structure including an oxide at grain boundary parts of magnetic grains, and the second magnetic layer is closest to the protection layer among layers within the perpendicular magnetic layer, and includes magnetic grains made of a CoCrPt alloy, and a nitride of carbon or a hydride of carbon.

    Magnetic recording medium having magnetic layer with nitride of carbon or hydride of carbon, and magnetic storage apparatus
    4.
    发明授权
    Magnetic recording medium having magnetic layer with nitride of carbon or hydride of carbon, and magnetic storage apparatus 有权

    公开(公告)号：US11295775B2

    公开(公告)日：2022-04-05

    申请号：US16953894

    申请日：2020-11-20

    Applicant: SHOWA DENKO K.K.

    Inventor： Kota Hasegawa ,  Katsuaki To

    IPC: G11B5/667 ,  G11B5/65 ,  G11B5/66

    Abstract: A magnetic recording medium includes a nonmagnetic substrate, a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic layer, and a protection layer that are arranged in this order. The perpendicular magnetic layer includes a first magnetic layer and a second magnetic layer that are arranged in this order on the orientation control layer. The first magnetic layer has a granular structure including an oxide at grain boundary parts of magnetic grains, and the second magnetic layer is closest to the protection layer among layers within the perpendicular magnetic layer, and includes magnetic grains made of a CoCrPt alloy, and a nitride of carbon or a hydride of carbon.

    Magnetic recording medium and magnetic recording and reproducing apparatus
    7.
    发明授权
    Magnetic recording medium and magnetic recording and reproducing apparatus 有权

    公开(公告)号：US10283155B2

    公开(公告)日：2019-05-07

    申请号：US15361658

    申请日：2016-11-28

    Applicant: SHOWA DENKO K.K.

    Inventor： Ken Inoue ,  Kota Hasegawa

    IPC: G11B5/66

    Abstract: A magnetic recording medium includes a non-magnetic substrate on which at least a soft magnetic underlayer, an orientation control layer, a perpendicular magnetic layer, and a protective layer are disposed. The perpendicular magnetic layer includes first to fourth magnetic layers. A first exchange coupling control layer is disposed between the first magnetic layer and the second magnetic layer. A second exchange coupling control layer is disposed between the second magnetic layer and the third magnetic layer. Following relations are satisfied where Kui is a magnetic anisotropic constant of an i-th magnetic layer, Msi is a saturation magnetization of the i-th magnetic layer, and ti is a film thickness of the i-th magnetic layer, Ku1>Ku2, Ku2>Ku3, Ms1×t1>Ms2×t2, Ms2×t2>Ms3×t3, Ku3

    Perpendicular magnetic recording medium and magnetic storage apparatus
    8.
    发明授权
    Perpendicular magnetic recording medium and magnetic storage apparatus 有权

    公开(公告)号：US09640213B2

    公开(公告)日：2017-05-02

    申请号：US14935529

    申请日：2015-11-09

    Applicant: SHOWA DENKO K.K. ,  JAPAN ATOMIC ENERGY AGENCY

    Inventor： Kota Hasegawa ,  Takahiro Ukai ,  Eishin Yamakawa ,  Shiro Entani ,  Seiji Sakai

    IPC: G11B5/66 ,  G11B5/72 ,  G11B5/82

    CPC classification number: G11B5/72 ,  G11B5/66 ,  G11B5/82

    Abstract: A perpendicular magnetic recording medium includes a perpendicular magnetic layer provided above a nonmagnetic substrate, and a protection layer provided on the perpendicular magnetic layer. The perpendicular magnetic layer has an hcp structure, and includes stacked layers having a (0002) crystal plane oriented parallel to a surface of the nonmagnetic substrate. An uppermost layer amongst the stacked layers includes polycrystal grains selected from a CoCr-base alloy, a CoPt-base alloy, a CoCrPt-base alloy, and a CoPtCr-base alloy. The protection layer makes contact with the uppermost layer of the perpendicular magnetic layer, and includes a single graphene layer or a graphene stack, and an amorphous carbon layer. The single graphene layer or the graphene stack is bonded in parallel to a (0002) crystal plane of the polycrystal grains.

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