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AssigneeHitachi, Ltd.
InventorsYoshihiro Shiroishi, Takeo Yamashita, Sadao Hishiyama, Noriyuki Kumasaka, Yoshibumi Matsuda, Hiroyuki Suzuki, Kazumasa Takagi, Norikazu Tsumita, Masaki Ohura, Tomoyuki Ohno
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Disclosed are longitudinal recording media comprising a composite magnetic film formed on a nonmagnetic substrate directly or through a nonmagnetic underlayer, in which all of magnetic thin films constituting the composite magnetic film are magnetically connected, the composite magnetic film has a single in-plane coercivity, and the in-plane coercivity is greater than the in-plane coercivity of a longitudinal magnetically anisotropic magnetic thin film constituting a magnetic thin film nearest to an information recording side among the magnetic thin films constituting the composite film.
A longitudinal magnetic recording medium comprising a composite magnetic film formed on a nonmagnetic substrate directly or through a nonmagnetic underlayer, in which all of the magnetic thin metal films constituting the composite magnetic film are magnetically coupled so as to have a single in-plane coercivity, and the in-plane coercivity is greater than the in-plane coercivity of a longitudinal magnetically anisotropic magnetic thin film constituting a magnetic thin metal film nearest to an information recording side among the magnetic thin metal films constituting the composite film.
A longitudinal magnetic recording medium having a composite magnetic film comprising at least two magnetic thin metal films formed on a nonmagnetic substrate directly or through a nonmagnetic underlayer, in which the magnetic thin metal film nearest to an information recording side is a longitudinal magnetically anisotropic magnetic thin metal film containing, as a main component, an alloy containing at least one element selected from a first group consisting of Co and Fe, and at least one element selected from a second group consisting of N, Tb, Mo, W, Gd, Y, Sm, Nd, Pr, Pm, Ce, Dy, La, Pt, Ir, Ti, Zr, Hf, V, Nb, Ta, Ru, Os, Rh, Pd, Al and Si, and/or Ni, the magnetic thin metal film nearest to the substrate side differs from the magnetic thin metal film nearest to the information recording side in components or composition and contains, as a main component an alloy containing at least one element selected from the above first group and at least one element selected from a third group consisting of Cu, Cr, Mo, W, Tb, Gd, Sm, Nd, Pm, Pr, Ce, Dy, Pt and Ir, and/or Ni, all of the magnetic thin metal films constituting the composite magnetic film are magnetically coupled so as to have a single in-plane coercivity of not less than 250 Oe in magnetization reversal of the composite magnetic film to a longitudinal head magnetic field.
A longitudinal magnetic recording medium comprising a composite magnetic film formed on a nonmagnetic substrate directly or through a nonmagnetic underlayer, in which the composite magnetic film is made of magnetic thin metal films and has a single in-plane coercivity and the in-plane coercivity is not less than 1,000 Oe, said in-plane coercivity being greater than the in-plane coercivity of a longitudinal anisotropic magnetic thin metal film which is nearest to an information recording side among the magnetic thin films constituting the composite film.
A magnetic memory unit comprising a longitudinal magnetic recording medium having a composite magnetic film made of a plurality of magnetic thin metal films on a non-magnetic substrate and having a longitudinal recording density of not less than 100 Mb/in.sup.2 said in plane coercivity being greater than the in-plane coercivity of a longitudinal anisotropic magnetic thin metal film which is nearest to an information recording side among the magnetic thin films constituting the composite film.
Dependencies are inferred from the claim text.