公开(公告)号：US11626128B2

公开(公告)日：2023-04-11

申请号：US17253254

申请日：2019-10-31

申请人： SONY GROUP CORPORATION

发明人： Masaru Terakawa ,  Minoru Yamaga

IPC分类号： G11B5/008 ,  G11B5/73

摘要： An object of the present disclosure is to provide a magnetic recording medium excellent in electro-magnetic conversion characteristic and thermal stability.
The present disclosure provides a tape-shaped magnetic recording medium including: a substrate; and a magnetic layer provided over the substrate and including a magnetic powder, in which the magnetic layer has an average thickness of equal to or less than 90 nm, the magnetic powder has an average aspect ratio of from 1.0 to 3.0, the magnetic powder has an average particle volume of equal to or less than 2,300 nm3, a coercive force Hc1 in a vertical direction of the magnetic recording medium is equal to or less than 4,500 Oe, a coercive force Hc2 in a longitudinal direction of the magnetic recording medium and the coercive force Hc1 satisfy a relation of Hc2/Hc1≤0.8, and the ratio Hrp/Hc1 of a residual coercive force Hrp of the magnetic recording medium measured using a pulsed magnetic field and the coercive force Hc1 is equal to or less than 2.0.

公开(公告)号：US12087340B2

公开(公告)日：2024-09-10

申请号：US17760555

申请日：2020-09-04

申请人： Sony Group Corporation

发明人： Natsuki Ichise ,  Minoru Yamaga ,  Katsunori Maeshima ,  Masaru Terakawa ,  Takeshi Takahashi ,  Tomoe Sato ,  Takashi Kataguchi

IPC分类号： G11B5/706 ,  G11B5/73

CPC分类号： G11B5/739

摘要： A magnetic recording medium is a tape-shaped magnetic recording medium that has a recording layer including an ε-iron oxide particle. An area ratio Rlow (=(Slow/Stotal)×100) of a total area Stotal of an SFD curve of the recording layer in a perpendicular direction and an area Slow of the SFD curve in which a coercivity Hc is in a range from −500 [Oe]≤Hc≤500 [Oe] is equal to or less than 5.5%.

公开(公告)号：US11830532B2

公开(公告)日：2023-11-28

申请号：US17637549

申请日：2019-10-31

申请人： Sony Group Corporation

发明人： Masaru Terakawa ,  Minoru Yamaga

IPC分类号： G11B5/78 ,  G11B5/008 ,  G11B5/714 ,  G11B5/70 ,  G11B25/06 ,  G11B23/107 ,  G11B15/60

CPC分类号： G11B5/78 ,  G11B5/00813 ,  G11B5/70 ,  G11B5/714 ,  G11B23/107 ,  G11B25/06 ,  G11B15/60

摘要： Provided is a magnetic recording medium capable of implementing higher-density recording. This magnetic recording medium includes a substrate containing a polyester and a magnetic layer disposed on the substrate, including a plurality of types of magnetic powder. A surface of the magnetic layer has an arithmetic average roughness Ra of 2.5 nm or less. PSD to a spatial wavelength of 5 μm is 2.5 μm or less. The magnetic layer has an average thickness of 90 nm or less. The magnetic powder has an average aspect ratio of 1.0 or more and 3.0 or less. A coercive force in a perpendicular direction is 3000 oersted or less. A ratio of a coercive force in a longitudinal direction to the coercive force in the perpendicular direction is 0.8 or less. A half-value width of an isolated waveform in a reproduced waveform of a data signal is 200 nm or less.

公开(公告)号：US11551711B2

公开(公告)日：2023-01-10

申请号：US17430874

申请日：2020-02-14

申请人： Sony Group Corporation

发明人： Natsuki Ichise ,  Masaru Terakawa ,  Katsunori Maeshima ,  Takashi Kataguchi ,  Takeshi Takahashi

IPC分类号： G11B5/706 ,  H01F1/34

摘要： A cobalt ferrite magnetic powder includes magnetic particles that have a uniaxial crystal magnetic anisotropy and contain cobalt ferrite. A peak top 2θ of a (3, 1, 1) plane determined by powder X-ray diffractometry using a CoKα ray is 41.3° or more and 41.5° or less. Some Cos contained in the magnetic particles are substituted with at least one selected from the group consisting of Zn, Ge, and a transition metal element other than Fe.