Metallic (i.e., Elemental Or Alloy) Substrate Patents (Class 428/846.6)
  • Publication number: 20120263975
    Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a substrate, and a multilayered magnetic recording layer formed on the substrate by alternately stacking two or more magnetic layers and two or more nonmagnetic layers. The magnetic layers and nonmagnetic layers of the multilayered magnetic recording layer are continuous layers. The magnetic layer includes a magnetic material portion, and a plurality of pinning sites dispersed in the magnetic material portion and made of a nonmagnetic metal different from a nonmagnetic material as a main component of the nonmagnetic layer. This perpendicular magnetic recording medium has magnetic characteristics by which a gradient a of a magnetization curve near the coercive force is 5 or more.
    Type: Application
    Filed: November 23, 2011
    Publication date: October 18, 2012
    Applicant: Kabushiki Kaisha Toshiba
    Inventor: Soichi OIKAWA
  • Publication number: 20120237798
    Abstract: According to one embodiment, a magnetic recording medium is formed by performing gas ion irradiation by using a magnetism deactivating gas on a stack including a perpendicular magnetic recording layer, an Ru nonmagnetic underlayer containing a magnetism deactivating element selected from chromium, titanium, and silicon, and a nonmagnetic substrate. Before gas ion irradiation, the perpendicular magnetic recording layer contains platinum and at least one of iron and cobalt. Gas ion irradiation is performed using nitrogen gas alone or a gas mixture of nitrogen gas and at least one gas selected from the group consisting of helium, hydrogen, and B2H6.
    Type: Application
    Filed: November 10, 2011
    Publication date: September 20, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Takeshi Iwasaki, Kaori Kimura, Hiroyuki Hyodo, Masatoshi Sakurai
  • Publication number: 20120200958
    Abstract: A perpendicular magnetic recording medium of the present invention comprises a non-magnetic substrate, and at least a backing layer, an under layer, an intermediate layer and a perpendicular magnetic recording layer, which are sequentially laminated on the non-magnetic substrate, wherein the backing layer is formed of a soft magnetic film having an amorphous structure, the under layer contains a NiW alloy containing any one or both of Co and Fe, the W content of the NiW alloy is within a range from 3 to 10 atom %, the total of the Co and Fe contents of the NiW alloy is 5 atom % or more and less than 40 atom %, the saturation magnetic flux density Bs of the NiW alloy is 280 emu/cm3 or more, the thickness of the under layer is within a range from 2 to 20 nm, and the intermediate layer contains Ru or a Ru alloy.
    Type: Application
    Filed: October 18, 2010
    Publication date: August 9, 2012
    Applicant: Showa Denko K.K.
    Inventor: Takashi Tanaka
  • Publication number: 20120164488
    Abstract: [Problem] An object is to provide a perpendicular magnetic recording medium that can realize both improvement in crystal orientation and refinement of crystal grain size and can achieve a higher recording density and a higher SN ratio, and a method of manufacturing the same. [Solution] A perpendicular magnetic recording medium 100 of the present invention is a perpendicular magnetic recording medium 100 having a base plate 100, and a laminate film including a first ground layer 150a provided on the base plate 100, a second ground layer 150b provided on the first ground layer 150a, and a main recording layer 160 provided on the second ground layer 150b and containing a magnetic material having a granular structure, wherein the magnetic material which constitutes the main recording layer 160 contains a CoCrPt alloy, and a material which constitutes the second ground layer 150b contains an Ru—Co oxide alloy.
    Type: Application
    Filed: June 22, 2011
    Publication date: June 28, 2012
    Applicant: WD MEDIA (SINGAPORE) PTE. LTD.
    Inventors: Hi SHIN, Iwao OKAMOTO
  • Publication number: 20120028076
    Abstract: According to one embodiment, a magnetic recording medium includes a substrate, a soft magnetic layer, an underlayer, a magnetic recording layer, and a protective layer, wherein the magnetic recording layer is provided with a pattern including recording portions and non-recording portions, the non-recording portions have a composition that is equal to a composition obtained by demagnetizing the recording portions, the non-recording portions contain at least one metal element selected from the group consisting of vanadium and zirconium and at least one element selected from the group consisting of nitrogen, carbon, boron and oxygen, and the at least one element selected from the group consisting of nitrogen, carbon, boron and oxygen is contained in the non-recording portions at a higher content than the content of the at least one element selected from the group consisting of nitrogen, carbon, boron and oxygen in the recording portions.
    Type: Application
    Filed: July 1, 2011
    Publication date: February 2, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Takeshi Iwasaki, Kaori Kimura, Yoshiyuki Kamata, Masatoshi Sakurai
  • Publication number: 20120009441
    Abstract: A method of manufacturing a perpendicular magnetic recording medium substrate is capable of reducing the waviness of all wavelength components and a recording medium is capable of reducing contact with a magnetic head to improve the flying stability of the magnetic head. The method includes two polishing operations. The first operation includes polishing a substrate having a Ni—P-based alloy underlayer with a first porous material that includes 0.1 wt % to 25 wt % of alumina, titania, silica, and zirconia abrasive while supplying a first slurry liquid including an organic or inorganic acid and a first abrasive to the underlayer of the substrate. The second operation includes polishing a surface of the underlayer polished in the first polishing with a second porous material while supplying a second slurry liquid including an organic or inorganic acid and a second abrasive with a grain diameter smaller than that of the first abrasive.
    Type: Application
    Filed: March 11, 2011
    Publication date: January 12, 2012
    Applicant: Fuji Electric Device Technology Co., Ltd.
    Inventors: Shoji SAKAGUCHI, Masaoki Miyakoshi, Jun Natsume
  • Publication number: 20110262776
    Abstract: A perpendicular magnetic recording medium is disclosed. The perpendicular magnetic recording medium includes a substrate; an intermediate layer disposed on the substrate; at least one soft underlayer (SUL) disposed between the substrate and the intermediate layer, wherein the soft underlayer contacts the intermediate layer and the substrate; and a magnetic recording layer disposed on the intermediate layer.
    Type: Application
    Filed: April 23, 2010
    Publication date: October 27, 2011
    Inventors: Shih-Chin Chen, Chang-Dar Tsai, Yu-Wen Chen, Shu-Hsien Liu, Hsin-Yen Tsai, Jie-Ming Chen
  • Publication number: 20110244273
    Abstract: A magnetic recording disk with pre-patterned surface features of elevated lands and recessed grooves or trenches, like a discrete-track media (DTM) or bit-patterned media (BPM) disk, has a planarized surface. A multilayered disk overcoat is used to protect the recording layer, and at least one of the overcoat layers functions as a stop layer for terminating a chemical-mechanical polishing (CMP) process that substantially planarizes the disk. All of the layers of the multilayered overcoat are located above the lands, but none of the overcoat layers, or a number of layers less than the number of layers over the lands, is located above the recesses.
    Type: Application
    Filed: April 2, 2010
    Publication date: October 6, 2011
    Inventors: Charles Mathew Mate, Franck Dreyfus Rose, Kurt Allan Rubin, Steven Gary Schmid, Tushar Keshubhai Suther
  • Patent number: 7943091
    Abstract: A chemical exposure indication device is disclosed. The device is removably attachable to a structure and includes a substrate having a first surface and a second surface and an indicating layer overlying the first substrate surface. The indicating layer includes a coating material that is chemically reactive with a pre-determined chemical compound that is known to degrade the structure. When the coating material is exposed to that corrosive compound in a pre-determined level associated with degradation of a metallic structure, the coating material provides a visual indication of the presence of the corrosive compound.
    Type: Grant
    Filed: November 16, 2007
    Date of Patent: May 17, 2011
    Assignee: The Boeing Company
    Inventors: Carl W. Beck, Rebecca L. Storey
  • Publication number: 20110045320
    Abstract: The present invention relates to a magnetic tunnel junction device and a manufacturing method thereof. The magnetic tunnel junction device includes: i) a first magnetic layer including a compound having a chemical formula of (A100-xBx)100-yCy; ii) an insulating layer deposited on the first magnetic layer; and iii) a second magnetic layer deposited on the insulating layer and including a compound having a chemical formula of (A100-xBx)100-yCy. The first and second magnetic layers have perpendicular magnetic anisotropy, A and B are respectively metal elements, and C is at least one amorphizing element selected from a group consisting of boron (B), carbon (C), tantalum (Ta), and hafnium (Hf).
    Type: Application
    Filed: February 16, 2010
    Publication date: February 24, 2011
    Applicant: Korea Institute of Science and Technology
    Inventors: Gyung-Min Choi, Byoung Chul Min, Kyung Ho Shin
  • Patent number: 7879471
    Abstract: A magnetic recording medium substrate has a polyester film having metallic oxide-containing layers (layers M) formed on both the surfaces, one layer on each surface, the layers M having a thickness of 50 to 200 nm each, characterized in that the magnetic recording medium substrate has a total light transmittance of 0 to 75% and a surface resistivity of 1×102 to 1×1013? on each surface.
    Type: Grant
    Filed: September 21, 2006
    Date of Patent: February 1, 2011
    Assignee: Toray Industries, Inc.
    Inventors: Masato Horie, Makoto Sato, Takuji Higashioji, Yukari Nakamori, Hiroaki Watanabe
  • Publication number: 20100233516
    Abstract: A perpendicular type of magnetic recording medium includes a substrate, a soft magnetic underlying section including a plurality of distinct layers soft magnetic material, a recording section, and an intermediate section upon which the recording section is formed. The intermediate section is provided to improve the crystal orientation and impart a desired magnetic characteristic to the recording section. An uppermost one of the layers of soft magnetic material which, of all of the layers of soft magnetic material, is disposed closest to the intermediate section is predisposed to induce the intermediate section to crystallize in a desired way as it is formed. Therefore, the intermediate section may have a minimal thickness and yet achieve a crystallization that is sufficient to control the forming of the recording section.
    Type: Application
    Filed: March 12, 2010
    Publication date: September 16, 2010
    Applicants: SAMSUNG ELECTRONICS CO., LTD., FUJI ELECTRIC DEVICE TECHNOLOGY CO., LTD.
    Inventors: Sok-hyun Kong, Hoo-san Lee, Sadayuki Watanabe, Shunji Takenoiri
  • Publication number: 20100215991
    Abstract: A perpendicular magnetic recording medium is provided, which has a soft magnetic layer, a seed layer, a first intermediate layer, a second intermediate layer and a perpendicular magnetic recording layer, formed in this order on a non-magnetic substrate, and is characterized in that the seed layer is comprised of a (002) crystal plane-orientated hcp structure, the first intermediate layer is comprised of a (110) crystal plane-orientated bcc structure and the second intermediate layer is comprised of a (002) crystal plane-orientated hcp structure. The (110) crystal plane-orientated bcc structure comprises at least 60 atomic % of Cr. The magnetic recording medium has fine and well discrete magnetic crystal grains with extremely small size and exhibits good perpendicular orientation in the perpendicular magnetic recording layer, and thus, the medium is capable of recording and reproducing information with high density.
    Type: Application
    Filed: July 25, 2008
    Publication date: August 26, 2010
    Applicant: SHOWA DENKO K.K.
    Inventors: Gohei Kurokawa, Yuzo Sasaki, Tatsu Komatsuda, Atsushi Hashimoto
  • Publication number: 20100215992
    Abstract: A magnetic recording medium used for perpendicular magnetic recording, the magnetic recording medium comprising: a substrate having a first surface and a second surface opposite to the first surface; a magnetic recording medium constituent layer formed on the first surface of the substrate, the magnetic recording medium constituent layer including at least a magnetic recording layer; a non-magnetic metal film formed on the second surface of the substrate; and a carbon-based protective film formed on the non-magnetic metal film.
    Type: Application
    Filed: February 22, 2010
    Publication date: August 26, 2010
    Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.
    Inventors: Junichi HORIKAWA, Kenji AYAMA, Masafumi ISHIYAMA, Toshikatsu YAMAGUCHI, Yusuke SETO
  • Publication number: 20100209741
    Abstract: A perpendicular magnetic recording medium is provided, which has a soft magnetic layer, an under layer, an intermediate layer and a perpendicular magnetic recording layer, and is characterized in that the perpendicular magnetic recording layer is comprised of at least one magnetic layer, which magnetic layer or at least one of which magnetic layers comprises cobalt-based ferromagnetic crystal grains and grain boundaries comprised of an oxide, wherein the ferromagnetic crystal grains further comprise ruthenium. The perpendicular magnetic recording medium has ferromagnetic crystal grains with extremely small grain size and exhibiting enhanced discretion, as well as good perpendicular orientation in the perpendicular magnetic recording layer, and thus, the medium is capable of recording and reproducing information with high density.
    Type: Application
    Filed: July 25, 2008
    Publication date: August 19, 2010
    Applicant: SHOWA DENKO K.K.
    Inventors: Yuzo Sasaki, Atsushi Hashimoto
  • Publication number: 20100167093
    Abstract: A perpendicular magnetic recording medium, which includes a first magnetic recording layer, a second magnetic recording layer, and a third magnetic recording layer disposed sequentially on a nonmagnetic substrate, and a coupling layer formed between the first and second magnetic recording layers. The first, second and third magnetic recording layers have an easy axis of magnetization in a direction perpendicular to a film plane of the nonmagnetic substrate. The first and second magnetic recording layers are ferromagnetically coupled via the coupling layer.
    Type: Application
    Filed: March 6, 2008
    Publication date: July 1, 2010
    Applicant: Fuji Electric Device Technology Co., Ltd
    Inventors: Akira Sato, Shunji Takenoiri, Yasushi Sakai
  • Publication number: 20100112379
    Abstract: A vertical magnetic recording disc (100) includes a base (10), a magnetic recording layer (22), and a medium protection layer (26). The magnetic recording layer (22) is a ferromagnetic layer having a granular structure where a granular portion is formed. The medium protection layer (26) contains nitrogen (N) atoms and carbon (C) atoms with a number ratio (N/C) in a range from 0.050 to 0.150. In a Raman spectrum obtained by exciting the medium protection layer (26) by argon ion laser light of wavelength 514.5 nm, from which a fluorescence is removed, the peak ratio Dh/Gh is in a range from 0.70 to 0.95, when a D peak Dh appearing in the vicinity of 1350 cm?1 is separated from G peak Gh appearing in the vicinity of 1520 cm?1 by the Gauss function.
    Type: Application
    Filed: March 28, 2008
    Publication date: May 6, 2010
    Applicants: HOYA CORPORATION, HOYA MAGNETICS SINGAPORE PTE. LTD.
    Inventors: Teiichiro Umezawa, Masafumi Ishiyama, Kenji Ayama, Tokichiro Sato
  • Publication number: 20100098972
    Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a substrate, soft magnetic underlying layer, nonmagnetic underlying layer, and perpendicular magnetic recording layer. The perpendicular magnetic recording layer has an array of magnetic structures each corresponding to 1 bit of recording information, and includes a crystalline hard magnetic recording layer having perpendicular magnetic anisotropy, and an amorphous soft magnetic recording layer. The hard and soft magnetic recording layers are coupled by exchange coupling.
    Type: Application
    Filed: December 28, 2009
    Publication date: April 22, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventor: Tomoyuki MAEDA
  • Publication number: 20100086809
    Abstract: A magnetic recording medium exhibiting a high recording density performance is disclosed. The perpendicular magnetic recording medium has a soft magnetic underlayer, a first seed layer, a second seed layer, an intermediate layer, a granular magnetic recording layer, a non-granular magnetic recording layer, a protective layer, and a lubricant layer laminated on a nonmagnetic substrate in this order. The first seed layer contains cobalt, nickel, and at least one element selected from a group consisting of Si, Cr, V, Zr, Nb, Ta, Ti, Cu, and Mo, and the second seed layer contains nickel, chromium, and at least one element selected from a group consisting of Si, V, Zr, Nb, Ta, Ti, Cu, and Mo.
    Type: Application
    Filed: September 2, 2009
    Publication date: April 8, 2010
    Applicant: FUJI ELECTRIC DEVICE TECHNOLOGY CO., LTD.
    Inventor: Yoshiyuki KUBOKI
  • Publication number: 20100081012
    Abstract: A perpendicular magnetic recording medium having a substrate, a Cr-doped Fe-alloy-containing underlayer containing about 8 to 18 at % Cr and a perpendicular recording magnetic layer, and a process for improving corrosion resistance of the recording medium and for manufacturing the recording medium are disclosed.
    Type: Application
    Filed: July 27, 2009
    Publication date: April 1, 2010
    Applicant: Seagate Technology LLC
    Inventors: Raj Nagappan Thangaraj, Mariana Rodica Munteanu, Erol Girt, Michael J. Stirniman, Thomas Patrick Nolan
  • Publication number: 20100075180
    Abstract: Provided is a magnetic recording medium substrate suitable for preparation of a DT medium and a patterned medium, and the magnetic recording medium substrate is possible to be of easy preparation of the DT medium and the patterned medium with no complicated processes. Disclosed is a magnetic recording medium substrate comprising a circular plate-shaped substrate made of a nonmagnetic base material, wherein a predetermined region of a surface of the substrate to form a magnetic film on the surface is more roughened than another region of the surface. When forming a magnetic film on this substrate, the magnetic film is formed in the region of the substrate surface, which is more roughened than the other region, to easily prepare the DT medium and the patterned medium.
    Type: Application
    Filed: September 22, 2007
    Publication date: March 25, 2010
    Inventors: Hiroaki Ueda, Masahiro Morikawa, Hideki Kawai
  • Publication number: 20090310255
    Abstract: A highly reliable magnetic recording medium is provided which has a recording layer formed in a concavo-convex pattern and wherein the recording layer is unlikely to cause a change in magnetic properties. The magnetic recording medium includes a substrate, a recording layer formed in a predetermined concavo-convex pattern over the substrate, convex portions of the concavo-convex pattern serving as recording elements; and a filler portion filling a concave portion between the recording elements. The filler portion comprises a metal-based main filler material and oxygen. Oxygen is unevenly distributed in the filler portion so that the ratio of the number of oxygen atoms to the total of the number of atoms of the main filler material and the number of oxygen atoms is greater in an upper surface portion of the filler portion than in a lower portion of the filler portion.
    Type: Application
    Filed: June 3, 2009
    Publication date: December 17, 2009
    Applicant: TDK CORPORATION
    Inventors: Shuichi Okawa, Kazuhiro Hattori, Narutoshi Fukuzawa, Takahiro Suwa
  • Publication number: 20090226765
    Abstract: A perpendicular magnetic recording medium having a soft magnetic backing layer is disclosed. The medium has reduced Co elution, improved corrosion resistance, and satisfactory electromagnetic transducing characteristics, without providing constraints on the configuration of the protective layer such as, for example, the thickness of the protective layer, film deposition processes or layer configuration.
    Type: Application
    Filed: March 3, 2009
    Publication date: September 10, 2009
    Applicant: FUJI ELECTRIC DEVICE TECHNOLOGY CO., LTD.
    Inventor: Yoshiyuki KUBOKI
  • Publication number: 20090197122
    Abstract: The perpendicular magnetic recording medium includes a non-magnetic underlayer composed of Ru or an Ru alloy having a columnar structure in which crystalline particles are isolated from each other by a space, a non-magnetic granular layer provided on the non-magnetic underlayer and composed of crystalline particles and a non-soluble phase and a granular magnetic layer provided on the non-magnetic granular layer and composed of CoCrPt alloy crystalline particles and the non-soluble phase, wherein when a lattice constant in an in-plane direction of the non-magnetic underlayer is a1, the lattice constant in the in-plane direction of the non-magnetic granular layer is a2, and the lattice constant in the in-plane direction of the granular magnetic layer is a3, the relation a1>a2>a3 is satisfied.
    Type: Application
    Filed: January 30, 2009
    Publication date: August 6, 2009
    Applicant: FUJITSU LIMITED
    Inventor: Ryosaku INAMURA
  • Publication number: 20090168506
    Abstract: Each layer in the magnetic multilayer film is a closed ring or oval ring and the magnetic moment or flux of the ferromagnetic film in the magnetic unit is in close state either clockwise or counterclockwise. A metal core is put in the geometry center position in the close-shaped magnetic multilayer film. The cross section of the metal core is a corresponding circular or oval. A MRAM is made of the closed magnetic multilayer film with or without a metal core. The close-shaped magnetic multilayer film is formed by micro process method. The close-shaped magnetic multilayer film can be used broadly in a great variety of device that uses a magnetic multilayer film as the core, such as MRAM, magnetic bead in computer, magnetic sensitive sensor, magnetic logic device and spin transistor.
    Type: Application
    Filed: December 31, 2006
    Publication date: July 2, 2009
    Inventors: Xiufeng Han, Ming Ma, Qihang Tan, Hongxiang Wei, Lixian Jiang, Yunan Han
  • Publication number: 20090142621
    Abstract: A magnetic recording media with a multilayer structure and methods for forming the media are described. The magnetic recording media includes a substrate, an underlayer on top of the substrate and a magnetic layer over the underlayer. The underlayer includes a CrN film formed by sputter depositing chromium in the presence of nitrogen or nitrogen containing compounds.
    Type: Application
    Filed: November 29, 2007
    Publication date: June 4, 2009
    Applicant: Seagate Technology LLC
    Inventors: Yingguo Peng, Bin Lu
  • Publication number: 20090142624
    Abstract: A method of producing a magnetic recording medium produces a medium having a magnetic recording layer disposed above a nonmagnetic intermediate layer, The nonmagnetic intermediate layer is formed by a sputtering using a target made of an oxide material. Oxygen gas or carbon dioxide gas is supplied during the sputtering in order to suppress a state where an oxygen supply becomes insufficient due to separation of oxygen atoms from the oxide material at a time of plasma generation.
    Type: Application
    Filed: November 29, 2008
    Publication date: June 4, 2009
    Applicant: FUJITSU LIMITED
    Inventors: Hideaki TAKAHOSHI, Hisato Shibata, Shinya Sato, Isatake Kaitsu, Akira Kikuchi
  • Publication number: 20090130492
    Abstract: Information storage devices and methods of manufacturing the same are provided. An information storage device includes a magnetic layer formed on an underlayer. The underlayer has at least one first region and at least one second region. The first and second regions have different crystallinity characteristics. The magnetic layer has at least one third region formed on the at least one first region and at least one fourth region formed on the at least one second region. The third and fourth regions have different magnetic anisotropic energy constants.
    Type: Application
    Filed: May 6, 2008
    Publication date: May 21, 2009
    Inventors: Sung-chul Lee, Sun-ae Seo, Young-jin Cho, Chang-won Lee
  • Publication number: 20090068500
    Abstract: Provided are a perpendicular magnetic recording medium and a method of manufacturing the same. The perpendicular magnetic recording medium includes: a substrate; a soft magnetic layer formed on the substrate; an underlayer formed on the soft magnetic layer; and a recording layer comprising a plurality of ferromagnetic layers and formed on the underlayer, wherein each of the plurality of ferromagnetic layers has a magnetic anisotropic energy which decreases as distance increases from the underlayer.
    Type: Application
    Filed: April 3, 2008
    Publication date: March 12, 2009
    Applicant: SAMSUNG ELECTRONICS CO., LTD.
    Inventors: Sok-hyun KONG, Sang-hwan PARK, Hoo-san LEE, Taek-dong LEE, Hoon-sang OH
  • Publication number: 20080213627
    Abstract: A magnetoresistance effect device includes: an insulator layer; a first and second ferromagnetic layer laminated to sandwich the insulator layer; a magnetic bias layer laminated with the second ferromagnetic layer; and a connecting section formed discontinuously on a side face of the insulator layer. The connecting section is not interposed between the second ferromagnetic layer and the magnetic bias layer. The connecting section is made of a ferromagnetic material, and electrically connecting between the first ferromagnetic layer and the second ferromagnetic layer. A method for manufacturing a magnetoresistance effect device includes: laminating a first and second ferromagnetic layer to sandwich an insulator layer, and laminating a magnetic bias layer with the second ferromagnetic layer; and forming a connecting section for electrically connecting between the first ferromagnetic layer and the second ferromagnetic layer by discontinuously forming a ferromagnetic material on a side face of the insulator layer.
    Type: Application
    Filed: February 29, 2008
    Publication date: September 4, 2008
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Yuichi Ohsawa, Shiho Nakamura
  • Publication number: 20080131737
    Abstract: A method of manufacturing a perpendicular magnetic recording medium and a substrate for the medium are disclosed, in which abnormal protrusions on an underlayer made of a Ni—P alloy are automatically eliminated while maintaining a flat surface with high accuracy on the underlayer, and appropriate texture traces remain to promote magnetization alignment in the vertical direction in a perpendicular magnetic recording medium without adversely affecting the magnetization alignment. In the method, texture processing is carried out on an underlayer made of a Ni—P alloy on a nonmagnetic base plate using a polishing tape while supplying mixed slurry of a surfactant and abrasive grains of polycrystalline diamond, and then, texture polishing is carried out on the underlayer processed by the texture processing, using a polishing tape while supplying slurry containing an abrasive material and an organic acid until the surface of the underlayer is polished to an arithmetic mean roughness Ra of at most 0.
    Type: Application
    Filed: October 26, 2007
    Publication date: June 5, 2008
    Applicant: Fuji Electric Device Technology Co., Ltd.
    Inventors: Shoji Sakaguchi, Hiroyuki Nakamura, Hideki Matsuo
  • Patent number: 6989204
    Abstract: A magnetic recording medium which includes a substrate having a front side and a backside, a longitudinal direction and a cross-web direction, with a particulate/binder or thin film magnetic layer formed over the front side of the substrate, wherein the magnetic medium has a cross-web dimensional difference from the magnetic recording head used therewith of less than 900 ?m/meter over a 35° C. temperature range, and over a 70% relative humidity range. Preferred substrates include thin metals, metal alloys, and thin glass films.
    Type: Grant
    Filed: June 22, 2004
    Date of Patent: January 24, 2006
    Assignee: Imation Corp.
    Inventors: Christopher J. Zwettler, Christopher A. Merton, Ramnath Subramaniam