公开(公告)号：US20200075053A1

公开(公告)日：2020-03-05

申请号：US16519157

申请日：2019-07-23

Applicant: SHOWA DENKO K.K.

Inventor： Takayuki FUKUSHIMA ,  Koji TAKE ,  Hisato SHIBATA ,  Takehiro YAMAGUCHI ,  Tomoo SHIGE ,  Lei ZHANG ,  Chen XU ,  Yuji UMEMOTO ,  Hiroshi KOYANAGI ,  Kazuya NIWA ,  Tetsuya KANBE

IPC: G11B11/105 ,  G11B5/73 ,  G11B11/24

Abstract: A heat-assisted magnetic recording medium includes a substrate, an underlayer, and a magnetic layer including an alloy having a L10 crystal structure and first and second layers, arranged in this order. Each of the first and second layers has a granular structure including C, SiO2, and BN at grain boundaries. Vol % of the grain boundaries in each of the first and second layers is 25 to 45 vol %. Vol % of C in the first layer is 5 to 22 vol %, and a volume ratio of SiO2 with respect to BN in each of the first and second layers is 0.25 to 3.5. Vol % of SiO2 in the second layer is greater than that of the first layer by 5 vol % or more. Vol % of BN in the second layer is smaller than that in the first layer by 2 vol % or more.

公开(公告)号：US20200005821A1

公开(公告)日：2020-01-02

申请号：US16445801

申请日：2019-06-19

Applicant: SHOWA DENKO K.K.

Inventor： Lei ZHANG ,  Takayuki FUKUSHIMA ,  Chen XU ,  Kazuya NIWA ,  Hisato SHIBATA ,  Takehiro YAMAGUCHI ,  Tetsuya KANBE ,  Tomoo SHIGE

IPC: G11B5/65

Abstract: A heat-assisted magnetic recording medium includes: a substrate; an underlayer; and a magnetic layer that is (001)-oriented. In the magnetic layer, a first magnetic layer and a second magnetic layer are stacked in this order from the underlayer side. The first magnetic layer and the second magnetic layer include an alloy having an L10 structure. The second magnetic layer includes a ferrite at grain boundaries of magnetic grains. The ferrite is one or more kinds selected from the group consisting of NiFe2O4, MgFe2O4, MnFe2O4, CuFe2O4, ZnFe2O3, CoFe2O4, BaFe2O4, SrFe2O4, and Fe3O4. A Curie temperature of the magnetic grains is lower than a Curie temperature of the ferrite.

公开(公告)号：US20190180782A1

公开(公告)日：2019-06-13

申请号：US16169065

申请日：2018-10-24

Applicant: SHOWA DENKO K.K.

Inventor： Katsumi MUROFUSHI ,  Yoshitaka ISHIBASHI ,  Takayuki FUKUSHIMA ,  Kazuya NIWA ,  Lei ZHANG ,  Yuji MURAKAMI ,  Hisato SHIBATA ,  Takehiro YAMAGUCHI ,  Chen XU ,  Tetsuya KANBE ,  Tomoo SHIGE

IPC: G11B5/851 ,  G11B5/65 ,  G11B5/72 ,  G11B5/82

Abstract: A magnetic recording medium includes a substrate, an underlayer provided on the substrate, and a magnetic layer provided on the underlayer and having a L10 structure and a (001) orientation. The magnetic layer has a granular structure in which an organic compound having a methylene skeleton or a methine skeleton is arranged at grain boundaries of magnetic grains.

公开(公告)号：US20210201947A1

公开(公告)日：2021-07-01

申请号：US17104504

申请日：2020-11-25

Applicant: SHOWA DENKO K.K.

Inventor： Takayuki FUKUSHIMA ,  Lei ZHANG ,  Chen XU ,  Hisato SHIBATA ,  Takehiro YAMAGUCHI ,  Hiroshi KOYANAGI ,  Yuji UMEMOTO

IPC: G11B5/851 ,  G11B5/73 ,  C23C14/08 ,  C23C14/35

Abstract: The present invention relates to a magnetic recording medium including a substrate; an underlayer laminated upon the substrate; and a magnetic layer laminated upon the underlayer, wherein the underlayer includes a first underlayer containing a compound represented by a following general formula: MgO(1-X), where X is within a range of 0.07 to 0.25, the magnetic layer includes a first magnetic layer containing an alloy having a L10 structure, and the alloy having the L10 structure includes B, and the first underlayer is in contact with the first magnetic layer.

公开(公告)号：US20190392860A1

公开(公告)日：2019-12-26

申请号：US16433377

申请日：2019-06-06

Applicant: SHOWA DENKO K.K.

Inventor： Lei ZHANG ,  Chen XU ,  Takayuki FUKUSHIMA ,  Kazuya NIWA ,  Tetsuya KANBE ,  Hisato SHIBATA ,  Takehiro YAMAGUCHI ,  Tomoo SHIGE

IPC: G11B5/31 ,  G11B5/48 ,  G11B5/65

Abstract: A heat-assisted magnetic recording medium includes: a substrate; an underlayer; and a magnetic layer including an alloy having an L10 structure, wherein the underlayer includes, from the substrate side, a bcc underlayer including a substance having a bcc structure, a first oxide layer that is in contact with the bcc underlayer, and a second oxide layer that is in contact with the magnetic layer. The bcc underlayer, the first oxide layer, and the second oxide layer are stacked in the recited order. The first oxide layer and the second oxide layer include magnesium oxide, and the second oxide layer further includes one or more compounds selected from the group consisting of vanadium oxide, vanadium nitride, and vanadium carbide.

公开(公告)号：US20180261245A1

公开(公告)日：2018-09-13

申请号：US15885013

申请日：2018-01-31

Applicant: SHOWA DENKO K.K.

Inventor： Kazuya NIWA ,  Tetsuya KANBE ,  Yuji MURAKAMI ,  Lei ZHANG ,  Hisato SHIBATA ,  Takayuki FUKUSHIMA ,  Satoru NAKAJIMA ,  Takehiro YAMAGUCHI

IPC: G11B5/65 ,  G11B5/39 ,  G11B5/73 ,  G11B5/012 ,  G11B5/74 ,  G11B5/714 ,  G11B5/187

CPC classification number: G11B5/656 ,  G11B5/012 ,  G11B5/1875 ,  G11B5/3133 ,  G11B5/3912 ,  G11B5/714 ,  G11B5/73 ,  G11B5/7325 ,  G11B5/746 ,  G11B2005/0021

Abstract: The invention provides a magnetic recording medium with an excellent signal-to-noise ratio during reading by reducing the noise produced during writing of data onto the magnetic recording medium, and increasing the signal level. The assisted magnetic recording medium according to one embodiment comprising a substrate, a base layer, and a magnetic layer composed mainly of an alloy with an L10-type crystal structure, the assisted magnetic recording medium having a pinning layer in contact with the magnetic layer, and the pinning layer including Co or an alloy composed mainly of Co.

公开(公告)号：US20180211688A1

公开(公告)日：2018-07-26

申请号：US15859973

申请日：2018-01-02

Applicant: SHOWA DENKO K.K.

Inventor： Takayuki FUKUSHIMA ,  Haruhisa OHASHI ,  Lei ZHANG ,  Yuji MURAKAMI ,  Hisato SHIBATA ,  Takehiro YAMAGUCHI ,  Tetsuya KANBE

IPC: G11B5/65

Abstract: A magnetic recording medium includes: a substrate; a first underlayer; a second underlayer; and a magnetic layer including an alloy having a L10 type crystal structure with a (001) orientation. The substrate, the first underlayer, the second underlayer, and the magnetic layer are stacked in this order. The first underlayer is a crystalline layer that includes Mo as a main component. The second underlayer is a crystalline layer that includes a material containing Mo as a main component and that includes an oxide. The content of the oxide in the second underlayer is in a range of from 2 mol % to 30 mol %. The oxide is an oxide of one or more kinds of elements selected from a group consisting of Cr, Mo, Nb, Ta, V, and W.

公开(公告)号：US20180204591A1

公开(公告)日：2018-07-19

申请号：US15850226

申请日：2017-12-21

Applicant: SHOWA DENKO K.K.

Inventor： Takayuki FUKUSHIMA ,  Haruhisa OHASHI ,  Lei ZHANG ,  Yuji MURAKAMI ,  Hisato SHIBATA ,  Takehiro YAMAGUCHI ,  Tetsuya KANBE

IPC: G11B5/70 ,  G11B5/65

Abstract: A magnetic recording medium includes: a substrate; a first underlayer; a second underlayer; and a magnetic layer including an alloy having a L10 type crystal structure with a (001) orientation. The substrate, the first underlayer the second underlayer, and the magnetic layer are stacked in this order. The first underlayer is a crystalline layer that includes W as a main component. The second underlayer is a crystalline layer that includes a material containing W as a main component and that includes an oxide. The content of the oxide in the second underlayer is in a range of from 2 mol % to 30 mol %. The oxide is an oxide of one or more kinds of elements selected from a group consisting of Cr, Mo, Nb, Ta, V, and W.

公开(公告)号：US20180182421A1

公开(公告)日：2018-06-28

申请号：US15841930

申请日：2017-12-14

Applicant: SHOWA DENKO K.K.

Inventor： Takayuki FUKUSHIMA ,  Kazuya NIWA ,  Lei ZHANG ,  Yuji MURAKAMI ,  Hisato SHIBATA ,  Takehiro YAMAGUCHI ,  Tetsuya KANBE

IPC: G11B5/667 ,  G11B11/105 ,  G11B5/65 ,  G11B5/73

CPC classification number: G11B5/667 ,  G11B5/65 ,  G11B5/7325 ,  G11B5/851 ,  G11B11/10589

Abstract: A magnetic recording medium includes a substrate, an underlayer, and a magnetic layer including an alloy having a L10 type crystal structure with a (001) orientation, wherein the substrate, the underlayer, and the magnetic layer are stacked in this order, the underlayer includes a first underlayer, the first underlayer is a crystalline layer that includes a material containing W as a main component and a nitride whose content ranges from 1 mol % to 80 mol %, and the nitride includes one or more elements selected from a group consisting of Al, B, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W.