Hitachi Maxell, Limited

Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Hitachi Maxwell, Ltd.

Satoshi Matsunuma

Akira Yano

Kiwamu Tanahashi

Tetsuya Kanbe

Tetsunori Koda

Enji Fujita

Yuzuru Hosoe

Fumiyoshi Kirino

Yoshio Takahashi

Ichiro Tamai

Hideaki Yamanaka

Tsuyoshi Onuma

Nobuyuki Inaba

Teruaki Takeuchi

Kouichirou Wakabayashi

Nagatugu Koiso

Shigehiko Fujimaki

Makoto Kitoh

Yuichi Kokaku

Takanobu Takayama

Harumi Hieida

Yoshihiro Shiroishi

Katsusuke Shimazaki

Kenji Furusawa

Takashi Naito

Hiroki Yamamoto

Norio Ohta

Masaaki Hayashi

Tetsuo Nakazawa

Akira Ishikawa

Hiroyuki Awano

Katsuo Abe

Hiroyuki Kataoka

Mitsutoshi Honda

Nobuo Nakagawa

Masaki Sekine

Tatsumi Hirano

Norio Ota

Tetsunori Kouda

A magnetic recording medium based on the perpendicular magnetic recording system includes a substrate; a back layer which is formed on the substrate and which is formed of a soft magnetic material; an in-plane magnetized layer which is formed on the back layer and which has in-plane magnetization; and a recording layer which is formed on the in-plane magnetized layer and which has perpendicular magnetization, wherein the in-plane magnetized layer has a coercivity in an in-plane direction larger than a magnetic field generated by residual magnetization in a perpendicular direction of the recording layer. The influence on the reproduction output, caused by the mirror image effect of the soft magnetic back layer is reduced in wide range recording densities, thereby improving the resolution by decreasing the difference between the reproduction outputs of the magnetic recording medium at the low recording density and at the high recording density.

Magnetic recording medium and magnetic recording apparatus

A magnetic recording medium based on the perpendicular magnetic recording system has a substrate which is formed of a non-magnetic material, a soft magnetic back layer which is formed of a soft magnetic material and which is formed on the substrate, an underlayer which is formed on the soft magnetic back layer, and a recording layer which is formed of an alloy magnetic material which is mainly composed of CoPtCr and contains an oxide, and which is formed on the underlayer. The recording layer is formed of two or more magnetic layers having different oxide contents, and the layer, which is included in the two or more magnetic layers for constructing the recording layer and which is provided on a side nearest to the underlayer, has the highest oxide content in the recording layer. The magnetic recording medium has more excellent magnetic characteristics with less medium noise.

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

In a magnetic storage apparatus having a magnetic recording medium, a drive unit for driving this medium in a prespecified recording direction, a magnetic head assembly including a recorder section and reproduction section, means for causing the magnetic head to move relatively with respect to the magnetic record medium, and a record/playback signal processor means for performing signal inputting to the magnetic head and for effecting reproduction of an output signal from the magnetic head, the reproduction section of said magnetic head is composed of a magnetic head of the magnetoresistance effect type, while said magnetic record medium is structured including a substrate and a magnetic layer formed thereover with one or several underlayers being sandwiched therebetween, wherein at least one of the underlayers is a specific layer that is made of amorphous or microcrystalline materials containing therein Ni as the principal or main component thereof and further containing at least one kind of element as selected from the group consisting of Nb and Ta.

Magnetic recording media and magnetic storage apparatus using the same

A perpendicular magnetic recording medium has a substrate, a magnetic functional layer provided on the substrate, and a magnetic recording layer stacked in contact with the magnetic functional layer and having perpendicular magnetic anisotropy. &#x2212;4&#xd7;2&#x3c0;Ms&#x2266;Ku&#x2266;6&#xd7;2&#x3c0;Msis satisfied, wherein Ku represents a perpendicular magnetic anisotropy constant of the magnetic functional layer and Ms represents a saturation magnetization. The magnetic moment of the magnetic functional layer is rotated in a direction of an applied magnetic field during the recording, and the magnetic moment acts on the magnetization of the recording layer in such a manner that the applied magnetic field is assisted thereby. Minute magnetic domains can be stably retained and excellent thermal disturbance resistance can be obtained.

Magnetic recording medium having a specific relation of coercive force HC and residual magnetization MR in perpendicular direction to substrate surface

A magnetic recording medium in which the medium noise is reduced and information can be recorded at a high S/N level, and a method for producing the magnetic recording medium are provided. A magnetic recording apparatus, which is excellent in thermal stability and which makes it possible to perform the high density recording, is provided. When films are formed for the magnetic recording medium based on the perpendicular magnetic recording method, the content of B in a seed layer is made sufficiently larger than the content of B in a recording layer. Accordingly, B is diffused from the seed layer to the recording layer to facilitate the segregation of B at the crystal grain boundary in the recording layer. Thereby, the magnetic interaction between the crystal grains in the recording layer is further reduced. Thus, it is possible to greatly reduce the transition noise.

A magnetic storage device has a magnetic layer, the magnetic crystal grains of which are separated by a nonmagnetic phase. The typical crystal grain is in the approximate shape of a sphere or an ellipsoid. The thickness of the magnetic crystal grains, which is in the direction perpendicular to the surface or the film, is smaller than that of the thickness of the magnetic film. The ratio of the coercive force, which is measured in the circumferential direction, to the coercive force, which is measured in the radial direction, (the orientation ratio of the coercive force), is larger than 1.0, but preferably nor greater than 3.0. Further, the area fraction of the magnetic grains having an extended axis within 30&#xb0; from the circumferential direction is equal to or more than 45%.

Magnetic recording medium and a magnetic storage apparatus

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

A magnetic recording medium based on the perpendicular recording system, which has high coercivity and low medium noise, is provided by using an underlayer which has a thin film thickness and which makes it possible to improve the orientation of a recording layer. The magnetic recording medium based on the perpendicular recording system has the recording layer which is formed of a CoPtCr alloy magnetic film containing oxygen. The magnetic recording medium has such a structure that an adhesive layer, a soft magnetic back layer, the underlayer, the recording layer, and a protective layerare successively stacked on a substrate. A CoCrRu film, which has a film thickness of 5 nm to 20 nm, is used as the underlayer for the recording layer formed of the CoPtCr alloy magnetic film containing oxygen. Thus, it is possible to improve the crystalline orientation of the recording layer with the underlayer having the thin film thickness.

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

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.

A magnetic recording mediumcomprises, on a substrate, a soft magnetic layer, a seed layer, and a recording layerhaving an artificial lattice structure. The seed layeris formed of Pd and one selected from the group consisting of Si, B, C, and Zr. Accordingly, the magnetic exchange coupling force of the recording layerin the in-plane direction can be weakened. Minute recording magnetic domains can be formed in the recording layer, and the magnetization transition area is distinct as well. Thus, the medium noise is reduced. That is, reproduction can be performed with a low medium noise even when information is recorded at a high density. A magnetic storage apparatus, which is provided with the magnetic recording medium as described above, can achieve an areal recording density of 150 Gigabits/square inch.

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

A magnetic recording medium comprises, on a substrate, a soft magnetic layer, a first seed layer, a second seed layer, and a recording layer having an artificial lattice structure. The first seed layer contains oxide of Fe. The second seed layer contains one of Pd and Pt, Si, and N. The magnetic exchange coupling force in the in-plane direction of the recording layer is weakened by the first seed layer and the second seed layer. Accordingly, minute recording magnetic domains can be formed in the recording layer, and the magnetization transition area is distinct as well. Even when information is recorded at a high density, the information can be reproduced with low noise. A magnetic storage apparatus, which is provided with such a magnetic recording medium, makes it possible to achieve an areal recording density of 150 gigabits/square inch.

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

In a magnetic storage apparatus having a magnetic recording medium, a drive unit for driving this medium in a prespecified recording direction, a magnetic head assembly including a recorder section and reproduction section, a way to cause the magnetic head to move relatively with respect to the magnetic record medium, and a record/playback signal processor for performing signal inputting to the magnetic head and for effecting reproduction of an output signal from the magnetic head, the reproduction section of said magnetic head is composed of a magnetic head of the magnetoresistance effect type, while said magnetic record medium is structured including a substrate and a magnetic layer formed thereover with one or several underlayers being sandwiched therebetween, wherein at least one of hte underlayers is a specific layer that is made of amorphous or microcrystalline materials containing therein Ni as the principal or main component thereof and further containing at least one kind of element as selected from the group consisting of Nb and Ta.

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Kamakura, Japan

Satoshi Matsunuma