Fuji Electric Co., Ltd.

Fuji Electric Device Technology Co., Ltd.

Tohoku University

Hiroyuki Uwazumi

Tadaaki Oikawa

Naoki Takizawa

Yasushi Sakai

Takahiro Shimizu

Miyabi Nakamura

Akira Iso

Sadayuki Watanabe

Kiyoto Yamaguchi

Takehito Shimatsu

Shunji Takenoiri

Hajime Kurihara

Yutaka Shimada

Youichi Tei

Toyoji Ataka

Kazuo Enomoto

Osamu Kitakami

Teruhisa Yokosawa

Satoshi Okamoto

Hajime Aoi

Yukiko Mamiya

Kazuhito Higuchi

Atsushi Ueda

Hiroaki Muraoka

Yoshihisa Nakamura

Akira Saito

Norihiko Nakajima

Keiji Ohkubo

Kengo Kainuma

Noboru Kurata

Kenji Ozawa

Hisashi Yamasaki

Yuko Arimoto

Mitsuo Masuda

Myabi Nakamura

Tsuyoshi Onitsuka

Hisasi Yamasaki

A perpendicular magnetic recording medium according to which both the thermal stability of the magnetization is good and writing with a magnetic head is easy, and moreover the SNR is improved. In the case of a perpendicular magnetic recording medium comprising a nonmagnetic substrate (), and at least a nonmagnetic underlayer (), a magnetic recording layer (), and a protective layer () formed in this order on the nonmagnetic substrate (), the magnetic recording layer () comprises a low Kregion () layer having a perpendicular magnetic anisotropy constant (Kvalue) of not more than 1&#xd7;10erg/cm, and a high Kregion () layer having a Kvalue of at least 1&#xd7;10erg/cm. Moreover, the magnetic recording layer () is made to have therein nonmagnetic grain boundaries that contain a nonmagnetic oxide and magnetically isolate crystal grains, which are made of a ferromagnetic metal, from one another.

Perpendicular magnetic recording medium

There is provided a perpendicular magnetic recording medium according to which both the thermal stability of the magnetization is good and writing with a magnetic head is easy, and moreover the SNR is improved. In the case of a perpendicular magnetic recording medium comprising a nonmagnetic substrate, and at least a nonmagnetic underlayer, a magnetic recording layerand a protective layerformed in this order on the nonmagnetic substrate, the magnetic recording layercomprises a low Kregionlayer having a perpendicular magnetic anisotropy constant (Kvalue) of not more than 1&#xd7;10erg/cm, and a high Kregionlayer having a Kvalue of at least 1&#xd7;10erg/cm. Moreover, the magnetic recording layeris made to have therein nonmagnetic grain boundaries that contain a nonmagnetic oxide and magnetically isolate crystal grains, which are made of a ferromagnetic metal, from one another.

The quantity of oxide contained in a magnetic layer is controlled to control the crystal grains and the segregation structure for ensuring low noise characteristic in a granular magnetic layer of a perpendicular magnetic recording medium. The granular magnetic layer consists of ferromagnetic crystal grains and a nonmagnetic grain boundary region mainly of an oxide surrounding the ferromagnetic crystal grains. The perpendicular magnetic recording medium has a nonmagnetic underlayer composed of a metal or alloy having hexagonal closest-packed crystal structure. The ferromagnetic crystal grain is composed of an alloy containing at least cobalt and platinum. The volume proportion of the nonmagnetic grain boundary region mainly of the oxide falls within a range of 15% to 40% of the volume of the total magnetic layer.

Perpendicular magnetic recording medium and method of manufacturing the same and product thereof

A perpendicular magnetic recording medium, which includes a nonmagnetic substrate, and a soft magnetic layer, a first orientation control layer, a nonmagnetic intermediate layer, and a perpendicular magnetic recording layer formed sequentially on the nonmagnetic substrate. The perpendicular magnetic recording medium further includes a second orientation control layer provided between the first orientation control layer and the nonmagnetic intermediate layer. The nonmagnetic intermediate layer has hexagonal close-packed (hcp) structure. The first orientation control layer has a face-centered cubic (fcc) structure. The second orientation control layer includes Co and Cr, and has the hcp structure.

A magnetic recording medium, and method of manufacturing the same, is provided with excellent recording performance by employing a granular magnetic layer having a specified composition. A magnetic recording medium according to the present invention comprises a nonmagnetic underlayer, a granular magnetic layer, a protective film, and a liquid lubrication layer sequentially laminated on a nonmagnetic substrate. The granular magnetic layer consists of ferromagnetic crystal grains containing cobalt and nonmagnetic grain boundary region surrounding the ferromagnetic crystal grains. The ferromagnetic crystal grains contain platinum in the range of 15 at % to 17 at %.

Magnetic recording medium and method for manufacturing the same

An object of the present invention is to provide a plating method on a glass base plate. The method allows forming a plating film on a base plate composed of a glass material with excellent adhesivity and homogeneity by means of an electroless plating method even to a thickness of 1 &#x3bc;m or more. Before forming a plating film by a step of electroless plating S, a surface treatment process is conducted on a surface of the base plate composed of a glass material. The surface treatment process comprises at least a step of glass activation treatment Sto increase quantity of silanol groups on the surface of the base plate at least by a factor of two using an aqueous solution of diluted acid, a step of silane coupling agent treatment S, a step of palladium catalyst treatment S, and a step of palladium bonding treatment S

Method of manufacturing a disk substrate for a magnetic recording medium

A perpendicular magnetic recording medium is disclosed in which a soft magnetic layer used as a low Klayer can be stably produced with high performance. Thermal stabilization of magnetization, ease of writing by a magnetic head, and SNR also are improved. A method of manufacturing the medium is disclosed. The perpendicular magnetic recording medium includes at least a nonmagnetic underlayer, a magnetic recording layer, and a protective layer formed in this order on a nonmagnetic substrate. The magnetic recording layer includes a low Klayer having a relatively small perpendicular magnetic anisotropy constant (Kvalue), and a high Klayer in which the Kvalue is relatively large, and the low Klayer includes a soft magnetic thin film including an iron group element-based microcrystal structure, in which a nitrogen element is added to a ferromagnetic material mainly containing one of metals of Co, Ni and Fe or an alloy of the metal. The thin film has a crystal structure of a face-centered cubic lattice or hexagonal close packed, and a preferred crystal orientation plane parallel to a plane of the film is a (111) plane in the face-centered cubic lattice structure, and a (002) plane in the hexagonal close packed structure.

Perpendicular magnetic recording medium and method of manufacturing the medium

A perpendicular magnetic recording medium has a granular magnetic layer and a nonmagnetic underlayer of a metal or an alloy having a hexagonal close packed (hcp) crystal structure. A seed layer of a metal or an alloy of a face-centered cubic (fcc) crystal structure is provided under the nonmagnetic underlayer. Such a perpendicular magnetic recording medium exhibits excellent magnetic characteristics even when the thickness of the underlayer or the total thickness of the underlayer and the seed layer is very thin. Excellent magnetic characteristics can be obtained even when of the substrate is not preheated. Accordingly, a nonmagnetic substrate, such as a plastic resin can be employed to reduce the manufacturing cost.

Perpendicular magnetic recording medium and a method of manufacturing the same

A perpendicular magnetic recording medium and method thereof, includes a nonmagnetic substrate; a soft magnetic under layer; an intermediate layer; a bilayer magnetic recording layer; a protective layer; and a liquid lubricant layer. According to a following order, the soft magnetic under layer, the intermediate layer, the bilayer magnetic recording layer, the protective layer, and the liquid lubricant layer are sequentially stacked on the nonmagnetic substrate. The bilayer magnetic recording layer includes a first magnetic layer including a CoCr alloy crystalline film, and a second magnetic layer including a rare earth-transition metal alloy noncrystalline film.

Fabrication method for perpendicular magnetic recording media

A disk substrate for a perpendicular magnetic recording medium is, disclosed. The substrate exhibits sufficient productivity, serves the function of a soft magnetic backing layer of the perpendicular magnetic recording medium, and scarcely generates noise. A perpendicular magnetic recording medium using such a substrate also is disclosed. The disk substrate comprises at least a soft magnetic underlayer formed on a nonmagnetic base plate by means of an electroless plating method. The thermal expansion coefficient of the soft magnetic underlayer is larger than a thermal expansion coefficient of the nonmagnetic disk-shaped base plate. A saturation magnetostriction constant &#x3bb;s satisfies a relation &#x3bb;s&#x2267;&#x2212;1&#xd7;10.

Disk substrate for a perpendicular magnetic recording medium and a perpendicular magnetic recording medium using the substrate

A substrate for a perpendicular magnetic recording medium has a soft magnetic underlayer that functions as a soft magnetic backing layer of a perpendicular magnetic recording medium. The substrate for a perpendicular magnetic recording medium has a nonmagnetic base made of Al&#x2014;Mg alloy or the like. The soft magnetic underlayer is formed of a Ni&#x2014;P alloy containing phosphorus in a range of 0.5 wt % to 6 wt % formed by electroless plating on the nonmagnetic base. The substrate can also include a nonmagnetic underlayer formed by electroless plating on the base before electroless plating the soft magnetic underlayer. To form the perpendicular magnetic recording medium, the surface of the soft magnetic is textured using free abrasive grains. Thereafter, a nonmagnetic seed layer, a magnetic recording layer, and a protective layer can be formed by sputtering. A soft magnetic supplemental layer also can be formed on the soft magnetic underlayer before forming the seed layer.

Substrate for a perpendicular magnetic recording medium, perpendicular magnetic recording medium, and manufacturing methods thereof

A perpendicular magnetic recording medium has a magnetic recording layer and laminated magnetic layers composed of different materials. In a first magnetic layer of the magnetic recording layer, ferromagnetic grains are surrounded by a nonmagnetic grain boundary region composed principally of oxide and/or nitride. In a second magnetic layer of the magnetic recording layer, ferromagnetic grains are surrounded by a nonmagnetic grain boundary region composed principally of chromium. The recording medium has an intermediate layer composed of a material having hcp or fcc structure. Advantageously, a heating process is conducted after forming the first magnetic layer and before forming the second magnetic layer. The medium achieves improvement in electromagnetic conversion characteristics and simultaneously improvement in corrosion resistance to provide a perpendicular magnetic recording medium with high recording density and simultaneously high reliability.

Perpendicular magnetic recording medium and a method for manufacturing the same

A magnetic recording medium exhibiting low noise and having a sufficiently high coercive force includes a magnetic layer having a granular structure including ferromagnetic crystal grains with a hexagonal closed packed structure and a nonmagnetic grain boundary region of mainly an oxide intervening between the crystal grains. An underlayer has a body-centered cubic lattice structure. A nonmagnetic intermediate layer with the hexagonal closest packed structure includes Ru, Os, and/or Re, which are provided between the magnetic layer and the underlayer. A degree of mismatching &#x394;=|d&#x2212;d|/dis at most 10%, for instance, in a range from 2.5% to 7.0%, where dis a spacing of lattice planes of the crystal grains in the magnetic layer and dis a spacing of the lattice planes of the crystal grains in the intermediate layer. A proportion of the crystal grains with a grain size of equal or greater than 8 nm are at most 10% of the crystal grains included in the intermediate layer and a standard deviation of the grain size is at most 1.4 nm. The layers are deposited without preheating the substrate.

Magnetic recording medium exhibiting low noise and high coercive force

A magnetic recording medium has a non-magnetic under-layer, a magnetic layer, a protective film and a liquid lubricant layer sequentially laminated on a non-magnetic substrate. The magnetic layer has a multi-layer structure laminated with two or more magnetic layer components, each of the magnetic layer components having ferromagnetic grains and non-magnetic grain boundaries surrounding the grain. The resulting magnetic recording medium has a granular magnetic layer exhibiting very high Hc accompanying high density of magnetic recording, while decreasing the amount of platinum needed for attaining the high Hc, and reducing media noise accompanying the high recording density.

Magnetic recording medium and method for manufacturing same

A magnetic recording medium for perpendicular magnetic recording system includes a nonmagnetic substrate and layers sequentially laminated on the substrate. The layers include a seed layer comprised of a metal or an alloy with a face centered cubic crystal structure, a nonmagnetic underlayer of a metal or an alloy with a hexagonal closest packed crystal structure, a magnetic layer having a granular structure including ferromagnetic crystalline grains with a hexagonal closest packed structure and nonmagnetic grain boundary region of mainly oxide surrounding the crystalline grains, a protective layer, and a liquid lubricant layer.

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Nagano, Japan

Hiroyuki Uwazumi