公开(公告)号：US06605374B2

公开(公告)日：2003-08-12

申请号：US10137398

申请日：2002-05-03

Applicant: Tetsuya Kanbe ,  Yoshio Takahashi ,  Akira Ishikawa ,  Ichiro Tamai ,  Yuzuru Hosoe ,  Yoshifumi Matsuda ,  Kiwamu Tanahashi ,  Tomoo Yamamoto

Inventor： Tetsuya Kanbe ,  Yoshio Takahashi ,  Akira Ishikawa ,  Ichiro Tamai ,  Yuzuru Hosoe ,  Yoshifumi Matsuda ,  Kiwamu Tanahashi ,  Tomoo Yamamoto

IPC: G11B566

CPC classification number: G11B5/65 ,  G11B5/64 ,  G11B5/653 ,  Y10S428/90 ,  Y10T428/12465 ,  Y10T428/12854 ,  Y10T428/26 ,  Y10T428/265

Abstract: The present invention provides a magnetic recording medium having a magnetic layer deposited on a substrate through a single-layer underlayer or a multilayer-underlayer, the magnetic layer includes magnetic crystal grains having an acicular structure or amorphous magnetic particles, an average grain size of the magnetic grain and a grain-size dispersion normalized by the average grain size are less than 16 nm and less than 0.5, respectively, a value Ku·v/kT which results from dividing a product of a magnetic anisotropy constant Ku and a volume v of the magnetic grain by a product of a Boltzmann constant k and an absolute temperature T is selected to be greater than 60, and a film thickness of the magnetic layer falls within twice of the average grain size. Thus, there can be realized a magnetic recording system in which a media noise can be reduced, a high S/N and a low bit error rate can be obtained and which has a high recording density of 2 gigabits per one square inches and an MTBF (mean time between failure) of higher than 300000 hours.

公开(公告)号：US06403242B1

公开(公告)日：2002-06-11

申请号：US09524914

申请日：2000-03-14

Applicant: Tetsuya Kanbe ,  Yoshio Takahashi ,  Akira Ishikawa ,  Ichiro Tamai ,  Yuzuru Hosoe ,  Yoshifumi Matsuda ,  Kiwamu Tanahashi ,  Tomoo Yamamoto

Inventor： Tetsuya Kanbe ,  Yoshio Takahashi ,  Akira Ishikawa ,  Ichiro Tamai ,  Yuzuru Hosoe ,  Yoshifumi Matsuda ,  Kiwamu Tanahashi ,  Tomoo Yamamoto

IPC: G11B566

CPC classification number: G11B5/65 ,  G11B5/64 ,  G11B5/653 ,  Y10S428/90 ,  Y10T428/12465 ,  Y10T428/12854 ,  Y10T428/26 ,  Y10T428/265

Abstract: The present invention provides a magnetic recording medium having a magnetic layer deposited on a substrate through a single-layer underlayer or a multilayer-underlayer, the magnetic layer includes magnetic crystal grains having an acicular structure or amorphous magnetic particles, an average grain size of the magnetic grain and a grain-size dispersion normalized by the average grain size are less than 16 nm and less than 0.5, respectively, a value Ku·v/kT which results from dividing a product of a magnetic anisotropy constant Ku and a volume v of the magnetic grain by a product of a Boltzmann constant k and an absolute temperature T is selected to be greater than 60, and a film thickness of the magnetic layer falls within twice of the average grain size. Thus, there can be realized a magnetic recording system in which a media noise can be reduced, a high S/N and a low bit error rate can be obtained and which has a high recording density of 2 gigabits per one square inches and an MTBF (mean time between failure) of higher than 300000 hours.