Hitachi, Ltd.

Hitachi Maxell, Limited

Other

Hitachi Global Storage Technologies Japan, Ltd.

Nobuyuki Inaba

Masaaki Futamoto

Yukio Honda

Yoshiyuki Hirayama

Tomoo Yamamoto

Yuzuru Hosoe

Fumiyoshi Kirino

Teruaki Takeuchi

Yoshibumi Matsuda

Kazuetsu Yoshida

Kenya Ito

Kazusuke Yamanaka

Hiroki Yamamoto

Masukazu Igarashi

Motoyasu Terao

Ken Takahashi

Sumio Hosaka

Mikio Suzuki

Eiji Koyama

Takashi Naitou

Hiroki Kuramoto

Shinji Narishige

Kenji Furusawa

Satoshi Matsunuma

Kouichirou Wakabayashi

Yasutaro Uesaka

Atsushi Nakamura

Ryoichi Nakatani

Akira Ishikawa

Toshihiko Sato

Emi Mangyo

Yoshihiro Shiroishi

Yoshio Takahashi

Ichiro Tamai

Hiroyuki Awano

Akira Yano

Tetsunori Koda

Enji Fujita

Hideaki Yamanaka

Hisashi Takano

Takashi Naito

Norio Ohta

Hideki Sawaguchi

Kenji Mori

Kyo Akagi

Takeshi Nakao

Tetsuo Nakazawa

Yoshinori Miyamura

Fumio Kugiya

Hirotsugu Fukuoka

Takayuki Munemoto

Tokuho Takagaki

Hiroyuki Kataoka

Mitsutoshi Honda

Koichiro Wakabayashi

Masaki Sekine

Tatsumi Hirano

Tsuyoshi Onuma

Harumi Hieida

Tetsunori Kouda

A magnetic recording medium having a substrate, an under-layer formed on the substrate, a magnetic layer formed on the substrate and a protective layer formed on the magnetic layer. The magnetic layer comprises Co, Cr and Pt with a thickness being from 10 nm to 22 nm. Further, a coercivity of the magnetic layer is not less than 2000 Oe, and a fluctuation field of magnetic viscosity at a field strength equal to remanence coercivity or coercivity is not less than 30 Oe.

Magnetic recording medium and magnetic recording and reproducing apparatus

A recording and reproducing apparatus including a recording magnetic head and a reproducing magnetic head with their floating height lowered for high density recordation and reproduction is provided. An information recording medium is provided on which it is possible to densely record information and from which it is possible to densely reproduce information by lowering the floating height of the recording and reproducing heads. The information recording medium includes a flat substrate and a recording layer provided on the substrate. Servo patterns and management information are recorded as magnetic marks on the recording layer in advance by a servo writer or the like. Because the substrate needs no recessed and embossed patterns formed in it, the slider of the recording and reproducing apparatus can be floated at a constant floating height lower than conventionally over the whole area of the medium. During information recordation, the position of the slider is controlled on the basis of the magneto-optical signals from the magnetic marks. During information reproduction, the reproducing magnetic head controls the slider position on the basis of the magnetic leakage fields leaking from the magnetic marks.

Information recording medium with magnetic marks, recording and reproducing apparatus therefor, and head positioning method using detected magnetic leakage fields from the magnetic marks

A magnetic recording medium comprises an information-recording film and a ferromagnetic film on a substrate. The information-recording film is composed of, for example, an amorphous ferrimagnetic material having perpendicular magnetization. Further, the ferromagnetic film is composed of a magnetic material which has saturation magnetization larger than that of the information-recording film. Accordingly, the leak magnetic flux from the ferromagnetic film is larger than that from the information-recording film. The magnetic recording medium and a magnetic recording apparatus are obtained, which are excellent in thermal stability and which are preferred to perform super high density recording.

Magnetic recording medium with high thermal stability, method for producing the same, and magnetic recording apparatus

An information recording medium, an information recording/reproduction head, and an information storage device are provided for performing a track servo operation at a smaller track pitch than that conventionally used without reducing the widths of servo burst patterns. The widths of servo burst patterns () are increased over a track pitch (TP) and the end of the servo burst pattern is disposed so as not to coincide with a center line () of an information track. In addition, a servo magnetic head () and a reproduction magnetic head () are implemented in one magnetoresistance element ().

Information recording medium, information recording/reproducing head, and information storage device

A magnetic recording mediumcomprises, on a substrate, a first orientation control layer, a second orientation control layer, a soft magnetic layer, a non-magnetic layer, a recording layer, and a carbon protective layer. The recording layeris formed of an FePt ordered alloy phase which exhibits ferromagnetism and an FePtordered alloy phase which exhibits paramagnetism. Accordingly, the magnetic coupling force, which acts between those of the FePt ordered alloy phase, is broken by the paramagnetic FePtordered alloy phase. The magnetic interaction between those of the FePt ordered alloy phase is reduced, and thus the noise is reduced. Further, the high density recording can be performed, and the medium is excellent in thermal stability, because the FePt ordered alloy having high crystalline magnetic anisotropy is used for the recording layer

Magnetic recording medium, method for producing the same, and magnetic recording apparatus

A magnetic recording medium comprises a magnetic recording layerwhich is formed by using an ordered alloy containing B on a substratecontaining an amorphous component. A part of B in the ordered alloy is segregated in a grain boundary, and thus the magnetic interaction, which acts between magnetic grains, can be reduced. Accordingly, it is possible to form fine and minute magnetic domains in the magnetic recording layer, and it is possible to reduce the medium noise as well. The temperature, at which the substrate is heated during the film formation of the magnetic recording layer, can be suppressed to be low, because the ordering temperature for the ordered alloy containing B is lower than those of ordered alloys not containing B. Therefore, it is possible to use a substrate made of glass which is suitable for the mass production. The magnetic recording layeris also excellent in thermal stability because of the use of the ordered alloy having high magnetic anisotropy. According to the present invention, it is possible to provide the magnetic recording medium for high density recording which is excellent in thermal stability and which involves low medium noise.

Magnetic recording medium and magnetic recording apparatus

An ferromagnetic thin film is used to provide a magnetic recording medium whose noise is low and whose S/N value is high. The ferromagnetic thin film as the magnetic film of the magnetic recording medium is such that the fluctuation field of magnetic viscosity at 25&#xb0; C. at the field strength equal to remanence coercivity or coercivity is not less than 15 oersteds and the coercivity is not less than 2000 oersteds.

Magnetic recording medium possessing a fluctuation field of not less than 30 Oe

An ultra-high density information recording media has an inorganic compound layer on a substrate , and in the inorganic compound layer , an oxide of at least one kind selected from silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, and zinc oxide exists in an amorphous state at a grain boundary of crystal grain of an oxide of at least one kind selected from cobalt oxide, iron oxide, and nickel oxide. The media has a magnetic layer made of an artificial lattice multilayer obtained by alternately laminating a Co layer or an alloy layer consisting of Co as a main phase and a metal element layer of at least one kind selected from Pt and Pd onto the layer . Thus, a distribution of magnetic properties serving as a pinning site of the movement of a magnetic wall in case of recording information to the magnetic layer is formed in the magnetic layer

Information recording media and information recording drive

The magnetic recording medium includes an underlayer formed of an inorganic compound layer, and a magnetic layer formed over the underlayer . The inorganic compound layer as the underlayer has crystal grains and at least one kind of oxide, the crystal grains having as main elements at least one of cobalt oxide, chromium oxide, iron oxide and nickel, the at least one kind of oxide lying as a non-crystalline phase in grain boundaries between the crystal grains and selected from among silicon oxide, aluminum oxide, titanium oxide, tantalum oxide and zinc oxide.

Magnetic recording disk

A magnetic recording medium ( ) includes a substrate ( ) and on the substrate ( ) a first underlying layer ( ), a second underlying layer ( ), a magnetic layer ( ), and a protective layer ( ). Because of the existence of the first underlying layer ( ) of Hf, initial growth layer having no specific crystal structure is prevented from growing in the second underlying layer ( ). The second underlying layer ( ) has a structure in which CoO particles having a cross section of a regular hexagon and separated by SiO portion are arranged in honeycomb. Since magnetic particles are epitaxially grown from CoO particles, the size of the magnetic particles and particle size distribution can be controlled, and the magnetic interaction between magnetic particles can be lessened. The underlying layer ( ) and the protective layer ( ) are formed by ECR sputtering. Such a magnetic recording medium is free from noise and thermal fluctuation, and ultrahigh recording density over 40 Gbit/inch is realized.

Magnetic recording medium and its production method, and magnetic recorder

Magnetic recording medium includes at least two layers having different magnetic anisotropy constants formed on a substrate and the perpendicular magnetic anisotropy of the second magnetic film of those magnetic films, far from the substrate surface, made equal to or larger than that of the first magnetic film near to the substrate surface, thus improving the magnetic isolation.

Magnetic recording medium and magnetic recording apparatus using the same

An amorphous magnetic recording medium comprising a substrate and an amorphous magnetic layer, where a magnetic domain formation-controlling layer comprising a main phase and 1 to 3 kinds of discrete spherical isolating phases arranged horizontally in lines in the main phase or 1 to 3 kinds of discrete spherical phases vertically stacked one upon another in the main phase is formed on the top side or the bottom side directly or through at least one of other layers to bring the amorphous magnetic layer into a finer magnetic domain structure, can satisfy high density recording.

Amorphous magnetic recording medium, process for producing the same and magnetic recording and reproduction apparatus

A magnetic recording apparatus includes a laser light source ( ), a recording magnetic head ( ) and a magnetoresistive element. The recording magnetic head includes a pair of magnetic poles ( and ), between which the magnetoresistive element is interposed. A rotary actuator (Sa) positions the recording magnetic head at a desired track of a magnetic recording medium. A laser beam can be radiated onto the magnetic recording medium to raise the temperature of a region ( ) of the medium. This region has a width of the order of the track width. The raised temperature lowers the coercive force of this region, where a recording magnetic field can be applied for high density recording. The rotary actuator may form a yaw angle (&thgr;) with a track of the magnetic recording medium. Even in this case, the recording magnetic head ( ) and the reproducing element have no tracking offset from the code track. In addition, if the size of the magnetic poles ( and ) of the recording magnetic head are set within a predetermined range, the region ( ) heated by the laser beam does not deviate from a recording magnetic field application region ( ).

Read/write head and magnetic recording device

It is an object of the present invention to provide a magnetic recording medium which has a high level of magnetic antisotropy energy, retains stably the state of recording magnetization within the operating temperature range and is suitable for high-density recording with a low noise level, and a magnetic storage device for the magnetic recording medium. For attaining the above object, the magnetic recording film of the magnetic recording medium is characterized in that its magnetic anisotropy energy constant K at an absolute temperature of 300 K is greater than 3.6&times;10 erg/cc and the average particle diameter is larger than 5 nm and smaller than 12 nm.

Method of manufacturing a magnetic recording media

A thin film magnetic recording medium including a magnetic layer having a fluctuation field defined as S/X , where S is magnetic viscosity and X is irreversible susceptibility X . The fluctuation field of the magnetic layer is not less than 15 oersteds.

Magnetic recording medium and magnetic recording and reproducing apparatus wherein the magnetic layer has a fluctuation of field; A or Hf of not less than 30 Oersteds

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Hasuda, Japan

Nobuyuki Inaba