Patents by Inventor Rajiv Yadav Ranjan

Rajiv Yadav Ranjan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6146754
    Abstract: A high areal density magnetic recording medium exhibiting high Hc, high SNR, high S* and substantially isotropic magnetic properties is achieved by depositing a thin seedlayer before depositing the underlayer. Embodiments include heating the seedlayer under vacuum in the presence of residual oxygen to induce appropriate crystalline orientation and surface morphology for nucleation and growth of the underlayer and magnetic layer having substantially isotropic magnetic properties.
    Type: Grant
    Filed: September 2, 1998
    Date of Patent: November 14, 2000
    Assignee: Seagate Technology, Inc.
    Inventors: Xing Song, Qixu Chen, Charles Leu, Rajiv Yadav Ranjan
  • Patent number: 6117570
    Abstract: High areal density magnetic recording media exhibiting low noise are formed with a surface oxidized NiAl seed layer. Embodiments include forming the surface oxidized NiAl seed layer on a glass or glass-ceramic substrate, and sequentially depositing a Cr or Cr-alloy, such as CrV, an intermediate CoCrTa layer and a CoCrPtTa magnetic layer.
    Type: Grant
    Filed: September 14, 1998
    Date of Patent: September 12, 2000
    Assignee: Seagate Technology, Inc.
    Inventors: Qixu David Chen, Liji Huang, Charles Leu, Rajiv Yadav Ranjan
  • Patent number: 6013161
    Abstract: A Co--Pt based magnetic alloy which has been doped with a relatively high amount of nitrogen, e.g., at or above 1 at. % is obtained having high coercivity, for example in the range of 1400 Oe or above, and an increased signal-to-noise ratio as compared to the same Co--Pt based alloy which has not been doped with nitrogen. The alloy is vacuum deposited, for example, by sputtering, and the nitrogen may be introduced from the sputtering gas or from the sputtering target. Other low-solubility elements providing the grain uniformity and isolation include: B, P, S, C, Si, As, Se and Te.
    Type: Grant
    Filed: October 28, 1997
    Date of Patent: January 11, 2000
    Assignee: Komag, Incorporated
    Inventors: Tu Chen, Tsutomu Tom Yamashita, John Ko-Jen Chen, Rajiv Yadav Ranjan, Keith Kadokura, Ting Joseph Yuen
  • Patent number: 5976326
    Abstract: A Co--Pt based magnetic alloy which has been sputtered with an oxide or nitride of a primary constituent of the magnetic layer, e.g., CoO below about 10 at. %, provides improved coercivity, squareness, and reduced noise as compared to magnetic alloys with oxygen introduced by other methods. The alloy is vacuum deposited, for example, by sputtering, and the oxide or nitride may be introduced from the sputtering target from which the magnetic layer materials come or from a separate sputtering target. Examples of such oxides and nitrides include CoO, Co.sub.2 0.sub.3, Co.sub.3 O.sub.4, CrO.sub.2, Cr.sub.2 O.sub.3, TiO.sub.2, Ta.sub.2 O.sub.5, Al.sub.2 O.sub.3, WO, CoN, Co.sub.2 N, TiN, TaN, CrN, NiN, etc.
    Type: Grant
    Filed: August 28, 1997
    Date of Patent: November 2, 1999
    Assignee: Komag, Incorporated
    Inventors: Rajiv Yadav Ranjan, Miaogen Lu, Tsutomu Tom Yamashita, Tu Chen
  • Patent number: 5908514
    Abstract: A new magnetic alloy exhibits high Hc and Ms while exhibiting excellent corrosion resistance, thereby providing ideal physical properties for high density recording applications. Other parameters of the media, such as SNR, PW50, and S are at least maintained, if not also improved. The alloy contains cobalt and up to 10 at. % Ni, up to 20 at. % Pt, up to 10 at. % Ta, up to 10 at. % Ti, and optionally up to 6 at. % B. The ratio of the tantalum to titanium in the alloy is between 3:1 and 1:3. The alloy is deposited by vacuum deposition (typically sputtering) on a similarly deposited non-magnetic alloy under layer. Nitrogen and/or oxygen may be introduced into the alloy during deposition to improve SNR. Other corrosion-resistant thin film alloys may also be obtained by the inclusion of Ta and Ti.
    Type: Grant
    Filed: October 24, 1996
    Date of Patent: June 1, 1999
    Inventors: Rajiv Yadav Ranjan, Tu Chen, Tsutomu Tom Yamashita, John Ko-Jen Chen
  • Patent number: 5851688
    Abstract: A Co--Pt based magnetic alloy which has been doped with a relatively high amount of nitrogen, e.g., at or above 1 at. % is obtained having high coercivity, for example in the range of 1400 Oe or above, and an increased signal-to-noise ratio as compared to the same Co--Pt based alloy which has not been doped with nitrogen. The alloy is vacuum deposited, for example, by sputtering, and the nitrogen may be introduced from the sputtering gas or from the sputtering target. Other low-solubility elements providing the grain uniformity and isolation include: B, P, S, C, Si, As, Se and Te.
    Type: Grant
    Filed: November 20, 1997
    Date of Patent: December 22, 1998
    Assignee: Komag, Inc.
    Inventors: Tu Chen, Tsutomu Tom Yamashita, John Ko-Jen Chen, Rajiv Yadav Ranjan, Keith Kadokura, Ting Joseph Yuen
  • Patent number: 5840394
    Abstract: A method for manufacturing a magnetic disk includes the step of providing first and second magnetic layers on a substrate. The first magnetic layer comprises Co. The portion of the first magnetic layer comprising Cr, Ta, Ti, W, Zr or Hf, if any, is less than 7.5 atomic % of the first magnetic layer (and preferably less than 5 atomic %). The second magnetic layer also comprises Co, and more than 7.5 atomic % of the second layer is Cr, Ta, Ti, W, Zr or Hf (and preferably more than 10 atomic %). We have discovered that the first and second magnetic layers can be made very thin without having a great reduction in coercivity.
    Type: Grant
    Filed: April 2, 1997
    Date of Patent: November 24, 1998
    Assignee: Komag, Incorporated
    Inventors: Rajiv Yadav Ranjan, Miaogen Lu
  • Patent number: 5820963
    Abstract: A method for manufacturing a magnetic disk includes the step of providing first and second cobalt alloy layers on a substrate. The first cobalt alloy layer is non-ferromagnetic, and the second cobalt alloy layer is ferromagnetic. The non-ferromagnetic layer is deposited on an underlayer. The non-ferromagnetic cobalt alloy provides a better crystal structure for depositing the subsequent ferromagnetic layer and thereby improves its magnetic properties. However, because the first cobalt alloy layer is not ferromagnetic, it does not adversely affect the magnetic characteristics of the disk.
    Type: Grant
    Filed: April 2, 1997
    Date of Patent: October 13, 1998
    Assignee: Komag, Incorporated
    Inventors: Miaogen Lu, Rajiv Yadav Ranjan
  • Patent number: 5736013
    Abstract: A Co--Pt based magnetic alloy which has been sputtered with an oxide or nitride of a primary constituent of the magnetic layer, e.g., CoO below about 10 at. %, provides improved coercivity, squareness, and reduced noise as compared to magnetic alloys with oxygen introduced by other methods. The alloy is vacuum deposited, for example, by sputtering, and the oxide or nitride may be introduced from the sputtering target from which the magnetic layer materials come or from a separate sputtering target. Examples of such oxides and nitrides include CoO, Co.sub.2 O.sub.3, Co.sub.3 O.sub.4, CrO.sub.2, Cr.sub.2 O.sub.3, TiO.sub.2, Ta.sub.2 O.sub.5, Al.sub.2 O.sub.3, WO, CoN, Co.sub.2 N, TiN, TaN, CrN, NiN, etc.
    Type: Grant
    Filed: January 3, 1997
    Date of Patent: April 7, 1998
    Assignee: Komag, Inc.
    Inventors: Rajiv Yadav Ranjan, Miaogen Lu, Tsutomu Tom Yamashita, Tu Chen
  • Patent number: 5658659
    Abstract: Media according to the present invention is comprised of individual magnetic grains as small as 300 .ANG. or smaller in diameter, which are uniformly spaced apart by a distance between 5 and 50 .ANG. by a solid segregant. This media will typically exhibit coercivity and remanent coercivity squareness of at least 0.8 each, a switching field distribution of less than 0.2, and a coercivity of at least 1500 Oe (with a minimum required Pt content), while simultaneously providing the lowest media jitter noise for optimum magnetic performance. The media is deposited at a low partial pressure of water and in the presence of an optimum amount of contributant gas on a doped nucleation layer for grain growth control.
    Type: Grant
    Filed: August 5, 1994
    Date of Patent: August 19, 1997
    Assignee: Komag, Inc.
    Inventors: Tu Chen, Rajiv Yadav Ranjan, Tsutomu Tom Yamashita, Miaogen Lu, Keith Kadokura, John Ko-Jen Chen, Ting Joseph Yuen