Patents by Inventor Gunn Choe

Gunn Choe 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: 9318140
    Abstract: A magnetic media having a novel cap layer that allows the cap layer having improved exchange coupling and reduced thickness. The cap layer is doped with a non-reactive element such as Ar, Kr, Xe, Ne or He preferably Ar. This doping reduces increases exchange coupling and reduces the dead layer, allowing the cap layer to be made thinner for reduced magnetic spacing and improved data recording performance.
    Type: Grant
    Filed: December 19, 2012
    Date of Patent: April 19, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Gunn Choe, Yoshihiro Ikeda
  • Patent number: 9129638
    Abstract: A perpendicular magnetic recording media comprises a substrate, a first magnetic oxide layer, a first exchange control layer, a second magnetic oxide layer, a second exchange control layer, and a magnetic cap layer positioned above the substrate, in this order. The first magnetic oxide layer may have an anisotropy energy (Ku) between 6×106 and 8×106 erg/cm3, and a magnetization (Ms) between 600 and 800 emu/cm3. The second magnetic oxide layer may have a Ku between 5×106 and 8×106 erg/cm3, and an Ms between 550 and 750 emu/cm3. The first exchange control layer may have an Ms between 0 and 100 emu/cm3. The second exchange control layer may have an Ms between 0 and 40 emu/cm3.
    Type: Grant
    Filed: January 22, 2015
    Date of Patent: September 8, 2015
    Assignee: HGST Netherlands B.V.
    Inventors: Gunn Choe, Yoshihiro Ikeda
  • Patent number: 9005781
    Abstract: A perpendicular recording medium having a perpendicular magnetic recording layer and a magnetically soft underlayer structure disposed beneath the recording layer. The soft underlayer structure includes at least first and second soft magnetic layers having different magnetic permeabilities to create a magnetic permeability gradient in the soft underlayer structure. One or more of the soft magnetic layers can be antiparallel coupled. The soft underlayer structure of the present invention having a magnetic permeability gradient advantageously leads to reduced adjacent track erasure (ATE) while maintaining good overwrite (OW) properties.
    Type: Grant
    Filed: September 14, 2012
    Date of Patent: April 14, 2015
    Assignee: Seagate Technology LLC
    Inventors: Jianing Zhou, B. Ramamurthy Acharya, E. Noel Abarra, Gunn Choe
  • Patent number: 8982510
    Abstract: Perpendicular magnetic recording disks and methods of fabricating perpendicular magnetic recording disks are described. The perpendicular magnetic recording disk includes a soft magnetic underlayer (SUL) structure, an interlayer, and a perpendicular magnetic recording layer. The SUL structure has an increased permeability from an inner radius of the disk to an outer radius of the disk. As a result, the magnetic write width (MWW) on the tracks of the disk is substantially uniform throughout the disk.
    Type: Grant
    Filed: November 5, 2007
    Date of Patent: March 17, 2015
    Assignee: HGST Netherlands B.V.
    Inventor: Gunn Choe
  • Publication number: 20140168817
    Abstract: A magnetic media having a novel cap layer that allows the cap layer having improved exchange coupling and reduced thickness. The cap layer is doped with a non-reactive element such as Ar, Kr, Xe, Ne or He preferably Ar. This doping reduces increases exchange coupling and reduces the dead layer, allowing the cap layer to be made thinner for reduced magnetic spacing and improved data recording performance.
    Type: Application
    Filed: December 19, 2012
    Publication date: June 19, 2014
    Applicant: HGST NETHERLANDS B.V.
    Inventors: Gunn Choe, Yoshihiro Ikeda
  • Publication number: 20130022842
    Abstract: A perpendicular recording medium having a perpendicular magnetic recording layer and a magnetically soft underlayer structure disposed beneath the recording layer. The soft underlayer structure includes at least first and second soft magnetic layers having different magnetic permeabilities to create a magnetic permeability gradient in the soft underlayer structure. One or more of the soft magnetic layers can be antiparallel coupled. The soft underlayer structure of the present invention having a magnetic permeability gradient advantageously leads to reduced adjacent track erasure (ATE) while maintaining good overwrite (OW) properties.
    Type: Application
    Filed: September 14, 2012
    Publication date: January 24, 2013
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Jianing Zhou, B. Ramamurthy Acharya, E. Noel Abarra, Gunn Choe
  • Patent number: 8277962
    Abstract: A perpendicular recording medium having a perpendicular magnetic recording layer and a magnetically soft underlayer structure disposed beneath the recording layer. The soft underlayer structure includes at least first and second soft magnetic layers having different magnetic permeabilities to create a magnetic permeability gradient in the soft underlayer structure. One or more of the soft magnetic layers can be anti-parallel coupled. The soft underlayer structure of the present invention having a magnetic permeability gradient advantageously leads to reduced adjacent track erasure (ATE) while maintaining good overwrite (OW) properties.
    Type: Grant
    Filed: September 10, 2010
    Date of Patent: October 2, 2012
    Assignee: Seagate Technology LLC
    Inventors: Jianing Zhou, B. Ramamurthy Acharya, E. Noel Abarra, Gunn Choe
  • Patent number: 8252367
    Abstract: Soft magnetic film fabricated with preferred uniaxial anisotropy for perpendicular recording. One type of cathode design has a field direction that is parallel to the direction of the Hex of the second SUL with a magnetically-pinned first SUL. In addition, SUL structures having low AP exchange energy also are disclosed. The SUL structure combines the cathode field direction of the SUL2 with the pinned SUL1. The SUL1 is magnetically pinned to the pinning layer and the pinning direction is parallel to the direction of the cathode field applied during deposition of the SUL1. High Hc ferro-magnetic materials may be deposited onto a heated substrate that is magnetized along the radial direction by the cathode field. The pinning field may be higher than the cathode field, indicating that the cathode field during deposition of the SUL2 cannot disturb the magnetic state of the SUL1 pinned to pinning layer.
    Type: Grant
    Filed: December 19, 2007
    Date of Patent: August 28, 2012
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Gunn Choe, Yoshihiro Ikeda, Masayoshi Shimizu, Kiwamu Tanahashi
  • Patent number: 8202636
    Abstract: A method is described for improving recording performance of a perpendicular media. The method includes controlling the anisotropy levels in different sublayers of the magnetic recording layers of the perpendicular media. Further, the different sublayers thicknesses can be altered to match the media to a particular head.
    Type: Grant
    Filed: December 23, 2008
    Date of Patent: June 19, 2012
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Gunn Choe, Yoshihiro Ikeda, Mohammad T. Mirzamaani, Kai Tang, Jinliu Wang
  • Publication number: 20120141832
    Abstract: A magnetic media having a multi-layer magnetic oxide structure with an uppermost magnetic oxide layer having a very low magnetic anisotropy energy. The magnetic oxide structure includes at least three magnetic oxide layers. An upper most magnetic oxide layer structure has a magnetic anisotropy energy of less than 1×106 erg/cm3 and a saturation magnetization of greater than 300 emu/cm3. The magnetic oxide structure improves media magnetization in response to a magnetic field. The low anisotropy layer responds easily to a magnetic field. This magnetic response is then transferred to the underlying layers which have a higher magnetic anisotropy for improved robustness in maintaining magnetization over time and even in a high temperature environment.
    Type: Application
    Filed: December 3, 2010
    Publication date: June 7, 2012
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Gunn Choe, Yoshihiro Ikeda
  • Patent number: 8168309
    Abstract: Perpendicular recording media with sublayers of dual oxide dopant magnetic materials are disclosed. The magnetic layer may comprise multiple sublayers of magnetic materials. In each sublayer, dual oxide dopants are incorporated. The compositions of the sublayers can be the same or different depending on the application. The magnetic layer may be deposited using a target comprising a mixture of CoPtCrB and dual oxides as dopants. The layer deposited with such targets can be the entire magnetic layer or a sublayer.
    Type: Grant
    Filed: August 13, 2009
    Date of Patent: May 1, 2012
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Gunn Choe, Mohammad T. Mirzamaani, Kai Tang, Jinliu Wang
  • Publication number: 20120064375
    Abstract: A method for manufacturing a magnetic media for perpendicular magnetic data recording. The method includes depositing a Ru layer in a pure oxygen atmosphere and then further depositing Ru in the presence of oxygen to form a thin pseudo onset layer. The pseudo onset layer can advantageously be depositing in the same deposition chamber and using the same target as that used to deposit the underlying Ru layer. This saves a great deal of manufacturing cost and complexity. The presence of the pseudo onset layer reduces grains size and increases grain separation in a high Ku magnetic layer deposited thereon, thereby increasing signal to noise ratio and decreasing magnetic core width (MCW).
    Type: Application
    Filed: September 14, 2010
    Publication date: March 15, 2012
    Applicant: Hitachi Global Storage Technologies Netherlands B. V.
    Inventors: Gunn Choe, Yoshihiro Ikeda
  • Patent number: 8110298
    Abstract: Perpendicular magnetic recording media having a magnetic capping layer that is exchange coupled to an underlying perpendicular magnetic recording layer. The magnetic coupling layer is a granular layer having a high saturation magnetization (Ms). The perpendicular magnetic recording layer can include magnetic grains separated by an oxide grain boundary phase.
    Type: Grant
    Filed: March 3, 2006
    Date of Patent: February 7, 2012
    Assignee: Seagate Technology LLC
    Inventors: Gunn Choe, B. Ramamurthy Acharya, Min Zheng, E. Noel Abarra
  • Patent number: 7901802
    Abstract: A perpendicular recording medium having a perpendicular magnetic recording layer and a magnetically soft underlayer structure disposed beneath the recording layer. The soft underlayer structure includes at least first and second soft magnetic layers having different magnetic permeabilities to create a magnetic permeability gradient in the soft underlayer structure. One or more of the soft magnetic layers can be anti-parallel coupled. The soft underlayer structure of the present invention having a magnetic permeability gradient advantageously leads to reduced adjacent track erasure (ATE) while maintaining good overwrite (OW) properties.
    Type: Grant
    Filed: March 15, 2007
    Date of Patent: March 8, 2011
    Assignee: Seagate Technology LLC
    Inventors: Jianing Zhou, B. Ramamurthy Acharya, E. Noel Abarra, Gunn Choe
  • Publication number: 20110038079
    Abstract: Perpendicular recording media with sublayers of dual oxide dopant magnetic materials are disclosed. The magnetic layer may comprise multiple sublayers of magnetic materials. In each sublayer, dual oxide dopants are incorporated. The compositions of the sublayers can be the same or different depending on the application. The magnetic layer may be deposited using a target comprising a mixture of CoPtCrB and dual oxides as dopants. The layer deposited with such targets can be the entire magnetic layer or a sublayer.
    Type: Application
    Filed: August 13, 2009
    Publication date: February 17, 2011
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Gunn Choe, Mohammad T. Mirzamaani, Kai Tang, Jinliu Wang
  • Publication number: 20100328818
    Abstract: A perpendicular recording medium having a perpendicular magnetic recording layer and a magnetically soft underlayer structure disposed beneath the recording layer. The soft underlayer structure includes at least first and second soft magnetic layers having different magnetic permeabilities to create a magnetic permeability gradient in the soft underlayer structure. One or more of the soft magnetic layers can be anti-parallel coupled. The soft underlayer structure of the present invention having a magnetic permeability gradient advantageously leads to reduced adjacent track erasure (ATE) while maintaining good overwrite (OW) properties.
    Type: Application
    Filed: September 10, 2010
    Publication date: December 30, 2010
    Applicant: Seagate Technology LLC
    Inventors: Jianing Zhou, B. Ramamurthy Acharya, E. Noel Abarra, Gunn Choe
  • Publication number: 20100159284
    Abstract: A method is described for improving recording performance of a perpendicular media. The method includes controlling the anisotropy levels in different sublayers of the magnetic recording layers of the perpendicular media. Further, the different sublayers thicknesses can be altered to match the media to a particular head.
    Type: Application
    Filed: December 23, 2008
    Publication date: June 24, 2010
    Inventors: Gunn Choe, Yoshihiro Ikeda, Mohammad T. Mirzamaani, Kai Tang, Jinliu Wang
  • Patent number: 7662492
    Abstract: Perpendicular magnetic recording media and methods of fabricating perpendicular magnetic recording media are described. The perpendicular magnetic recording medium of one embodiment includes a soft magnetic underlayer (SUL), an interlayer, and a perpendicular magnetic recording layer. The interlayer comprises a layer formed from a first material (e.g., NiWCr) having a face-centered-cubic (FCC) structure, a layer formed from a second material (e.g., Cr) having a body-centered-cubic (BCC) structure, and a layer formed from a third material (e.g., Ru) having a hexagonal-close-packed (HCP) structure.
    Type: Grant
    Filed: April 17, 2007
    Date of Patent: February 16, 2010
    Assignee: Hitachi Global Storage Techologies Netherlands, B.V.
    Inventors: Gunn Choe, Kai Tang
  • Patent number: 7592079
    Abstract: A magnetic disk for information storage that includes a substrate and an information layer for containing information. The information layer includes a upper (e.g., recording) and lower (e.g., stabilizing) layers. The information layer has a remanence-squareness-thickness-product (“Mrt”) that varies radially between first and second disk radii. At least one of the following conditions is true: (i) the information layer has a coercivity that is at least substantially constant between the first and second disk radii; (ii) the lower magnetic layer has a magnetic anisotropy energy of no more than about 1.5×106 erg/cm3; and (iii) the magnetic anisotropy energy of the upper magnetic layer is at least about 150% of the magnetic anisotropy energy of the lower magnetic layer.
    Type: Grant
    Filed: July 1, 2004
    Date of Patent: September 22, 2009
    Assignee: Seagate Technology LLC
    Inventors: B. Ramamurthy Acharya, Gunn Choe
  • Publication number: 20090162573
    Abstract: Soft magnetic film fabricated with preferred uniaxial anisotropy for perpendicular recording. One type of cathode design has a field direction that is parallel to the direction of the Hex of the second SUL with a magnetically-pinned first SUL. In addition, SUL structures having low AP exchange energy also are disclosed. The SUL structure combines the cathode field direction of the SUL2 with the pinned SUL1. The SUL1 is magnetically pinned to the pinning layer and the pinning direction is parallel to the direction of the cathode field applied during deposition of the SUL1. High Hc ferro-magnetic materials may be deposited onto a heated substrate that is magnetized along the radial direction by the cathode field. The pinning field may be higher than the cathode field, indicating that the cathode field during deposition of the SUL2 cannot disturb the magnetic state of the SUL1 pinned to pinning layer.
    Type: Application
    Filed: December 19, 2007
    Publication date: June 25, 2009
    Applicant: HITACHI GLOBAL STORAGE TECHNOLOGIES NETHERLANDS BV
    Inventors: Gunn Choe, Yoshihiro Ikeda, Masayoshi Shimizu, Kiwamu Tanahashi