Patents by Inventor B. Ramamurthy Acharya

B. Ramamurthy Acharya 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: 11074934
    Abstract: HAMR media with a magnetic recording layer having a reduced Curie temperature and methods of fabricating the HAMR media are provided. One such HAMR medium includes a substrate, a heat sink layer on the substrate, an interlayer on the heat sink layer, and a multi-layer magnetic recording layer on the interlayer. In such case, the multi-layer magnetic recording layer includes a first magnetic recording layer including an alloy selected from FePtX and CoPtX, where X is a material selected from the group consisting of Cu, Ni, and combinations thereof, a second magnetic recording layer on the first magnetic recording layer and having at least one material different from the materials of the first magnetic recording layer, and a third magnetic recording layer on the second magnetic recording layer and having at least one material different from the materials of the first magnetic recording layer.
    Type: Grant
    Filed: September 25, 2015
    Date of Patent: July 27, 2021
    Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.
    Inventors: Hua Yuan, Antony Ajan, Oleg Krupin, B. Ramamurthy Acharya
  • Patent number: 9824710
    Abstract: A heat-assisted magnetic recording (HAMR) medium has a multilayered or laminated heat-sink structure. The laminated heat-sink structure includes a first heat-sink layer and a RuAl—X thermal barrier layer between the medium substrate and the first heat-sink layer. The laminated heat-sink structure may include a second heat-sink layer may between the substrate and the RuAl—X thermal barrier layer. In the RuAl—X thermal barrier layer, X is selected from C and one or more oxides of Si, Ti, W, Zr and Hf. The HAMR medium with the laminated heat-sink structure reduces the amount of required laser current as compared to a similar HAMR medium with a conventional single heat-sink layer of the same thickness, while also slightly improving magnetic properties and recording performance.
    Type: Grant
    Filed: May 1, 2017
    Date of Patent: November 21, 2017
    Assignee: Western Digital Technologies, Inc.
    Inventors: Hua Yuan, Shahid Ali Pirzada, Hoan Cong Ho, Paul Christopher Dorsey, B. Ramamurthy Acharya
  • Patent number: 9542968
    Abstract: FePt-based heat assisted magnetic recording (HAMR) media comprising a thick granular FePt:C magnetic recording layer capable of maintaining a single layer film having desirable magnetic properties. According to one embodiment, the thick granular FePt:C magnetic recording layer comprises a plurality of carbon doped FePt alloy columnar grains, where the plurality of carbon doped FePt alloy columnar grains comprise a carbon gradient along the thickness of the hard magnetic recording layer.
    Type: Grant
    Filed: October 31, 2013
    Date of Patent: January 10, 2017
    Assignee: WD MEDIA, LLC
    Inventors: Hua Yuan, Alexander S. Chernyshov, B. Ramamurthy Acharya
  • Patent number: 9449633
    Abstract: A recording medium having improved signal-to-noise ratio (SNR) capabilities and head-disk interface characteristics includes an etched smoothened underlayer, over which the recording layer is grown. One mechanism for increasing the SNR is by growing more columnar magnetic grain structures within the recording layer, which is facilitated by a smoother underlayer template.
    Type: Grant
    Filed: November 6, 2014
    Date of Patent: September 20, 2016
    Assignee: WD Media, LLC
    Inventors: Shahid Pirzada, Tomoko Seki, B. Ramamurthy Acharya, Antony Ajan
  • Patent number: 9401170
    Abstract: FePt-based perpendicular magnetic recording (PMR) media including an epitaxial exchanged coupling layer (EECL) between FePtX magnetic recording layers. The degree of exchange coupling may be modulated by the EECL while the texture is transferred between the magnetic recording layers. With an EECL of proper composition and thickness, the FePt-based composite media has high anisotropy field and low saturation magnetic field.
    Type: Grant
    Filed: November 24, 2009
    Date of Patent: July 26, 2016
    Assignee: WD Media, LLC
    Inventors: Chengjun Sun, Donald C. Stafford, B. Ramamurthy Acharya
  • Publication number: 20160148634
    Abstract: Systems and methods for forming magnetic recording media with improved columnar growth for energy assisted magnetic recording are provided. In one such method, a first sub-layer of a magnetic layer is formed on a substrate, the magnetic layer including a magnetic material and a plurality of non-magnetic segregants, a top surface of the first sub-layer is etched to substantially remove the non-magnetic segregants accumulated on the top surface, and a second sub-layer of the magnetic layer is formed on the first sub-layer.
    Type: Application
    Filed: February 2, 2016
    Publication date: May 26, 2016
    Inventors: ANTONY AJAN, ALEXANDER S. CHERNYSHOV, HUA YUAN, B. RAMAMURTHY ACHARYA
  • Patent number: 9269480
    Abstract: Systems and methods for forming magnetic recording media with improved columnar growth for energy assisted magnetic recording are provided. In one such method, a first sub-layer of a magnetic layer is formed on a substrate, the magnetic layer including a magnetic material and a plurality of non-magnetic segregants, a top surface of the first sub-layer is etched to substantially remove the non-magnetic segregants accumulated on the top surface, and a second sub-layer of the magnetic layer is formed on the first sub-layer.
    Type: Grant
    Filed: March 30, 2012
    Date of Patent: February 23, 2016
    Assignee: WD Media, LLC
    Inventors: Antony Ajan, Alexander Chernyshov, Hua Yuan, B. Ramamurthy Acharya
  • Patent number: 9218850
    Abstract: A heat-assisted magnetic recording (HAMR) medium having improved signal-to-noise ratio capabilities includes a high-temperature exchange break layer (EBL) inserted between magnetic recording layers, where the high-temperature exchange break layer material is capable of maintaining its chemical properties at temperatures exceeding 300° C. The high-temperature EBL may include a non-metallic compound including at least one of an oxide, a carbide, and a nitride.
    Type: Grant
    Filed: December 23, 2014
    Date of Patent: December 22, 2015
    Assignee: WD Media, LLC
    Inventors: Bincheng Wang, Alexander S. Chernyshov, Hua Yuan, Antony Ajan, B. Ramamurthy Acharya
  • Patent number: 9190094
    Abstract: Aspects of the present invention relate to a perpendicular magnetic recording (PMR) media stack and methods for fabricating the same. The PMR media stack has a novel grain isolation initiation layer (GIIL) and/or a novel exchange-break layer (EBL) that can improve the signal-to-noise performance of the PMR media stack. The PMR media stack includes a substrate, a soft underlayer on the substrate, an interlayer positioned on the soft underlayer, and a grain isolation initiation layer (GIIL) positioned on the interlayer, a magnetic layer positioned on the GIIL, and an exchange break layer (EBL) positioned on the magnetic layer. The GIIL and/or EBL includes a CoCrRu-oxide.
    Type: Grant
    Filed: June 6, 2013
    Date of Patent: November 17, 2015
    Assignee: Western Digital (Fremont)
    Inventors: Daehoon Hong, Sy Vu, Kyongha Kang, B. Ramamurthy Acharya
  • Patent number: 9177585
    Abstract: A method and system provide a magnetic recording media usable in a heat assisted magnetic recording (HAMR) disk drive. The magnetic recording media includes a magnetic recording layer, a crystalline underlayer, and a crystalline heat sink layer. The crystalline underlayer is between the crystalline heat sink layer and the magnetic recording layer. The magnetic recording layer stores magnetic data. The crystalline underlayer has a first crystal structure. The crystalline heat sink layer has a second crystal structure.
    Type: Grant
    Filed: December 4, 2013
    Date of Patent: November 3, 2015
    Assignee: WD Media, LLC
    Inventors: Tomoko Seki, Antony Ajan, Hua Yuan, Alexander S. Chernyshov, Bincheng Wang, B. Ramamurthy Acharya
  • Patent number: 9028985
    Abstract: A magnetic recording (PMR) disk structure is described. The PMR disk structure may include a magnetic capping layer being substantially free of an oxide, an upper magnetic layer with an oxide content disposed directly below and in contact with the magnetic capping layer, and an upper exchange coupling layer disposed below the upper magnetic layer.
    Type: Grant
    Filed: March 31, 2011
    Date of Patent: May 12, 2015
    Assignee: WD Media, LLC
    Inventors: Mrugesh Desai, Kyongha Kang, Jian Zhou, B. Ramamurthy Acharya
  • 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: 8993133
    Abstract: A perpendicular magnetic recording (PMR) media including a non-magnetic or superparamagnetic grain isolation magnetic anisotropy layer (GIMAL) to provide a template for initially well-isolated small grain microstructure as well as improvement of Ku in core grains of a magnetic recording layer. The GIMAL composition may be adjusted to have lattice parameters similar to a bottom magnetic recording layer and to provide a buffer for reducing interface strains caused by lattice mismatch between the bottom magnetic recording layer and an underlying layer.
    Type: Grant
    Filed: December 23, 2010
    Date of Patent: March 31, 2015
    Assignee: WD Media, LLC
    Inventors: Shaoping Li, B. Ramamurthy Acharya
  • Patent number: 8947987
    Abstract: Aspects of the present invention are directed to heat assisted magnetic recording (HAMR) media with a CoCrPtB based capping layer design that is capable of reducing switching field distribution and boosting signal-to-noise ratio of HAMR media. In one embodiment of the invention, a recording medium for heat assisted magnetic recording (HAMR) includes a substrate, a magnetic recording layer on the substrate, and a capping layer on and directly in contact with the magnetic recording layer. The capping layer includes CoCrPtB.
    Type: Grant
    Filed: July 1, 2013
    Date of Patent: February 3, 2015
    Assignee: WD Media, LLC
    Inventors: Bincheng Wang, Alexander S. Chernyshov, Hua Yuan, Tomoko Seki, Antony Ajan, B. Ramamurthy Acharya
  • Patent number: 8945732
    Abstract: A recording medium comprising a magnetic recording layer having an axis of magnetic anisotropy substantially perpendicular to the surface thereof, a soft magnetic underlayer disposed under the magnetic recording layer and physically coupled to the magnetic recording layer through one or more intermediate layers magnetically decoupling the soft magnetic underlayer from the magnetic recording layer, and an orientation initialization layer disposed between the magnetic recording layer and the soft magnetic underlayer.
    Type: Grant
    Filed: August 5, 2010
    Date of Patent: February 3, 2015
    Assignee: WD Media, LLC
    Inventors: Hua Yuan, Alexander Chernyshov, B. Ramamurthy Acharya
  • Patent number: 8941950
    Abstract: Various embodiments provide for a heat assisted magnetic recording (HAMR) media comprising: a magnetic recording layer; a barrier layer disposed under the magnetic recording layer; a first underlayer disposed under the barrier layer; and an amorphous seedlayer disposed under the first underlayer. For some embodiments, the recording medium may comprise: a magnetic recording layer including FePt alloy, a CoPt alloy, or a FePd alloy; a barrier layer including MgO, TiC, TiN, CrN, TiCN, ?-WC, TaC, HfC, ZrC, VC, NbC, or NiO; a first underlayer including RuAl-oxide, NiAl, FeAl, AlMn, CuBe, or AlRe; or an amorphous seedlayer including a Cr—X alloy, where X comprises Al, B, C, Cu, Hf, Ho, Mn, Mo, Ni, Ta, Ti, V, W, or Ru.
    Type: Grant
    Filed: May 23, 2012
    Date of Patent: January 27, 2015
    Assignee: WD Media, LLC
    Inventors: Hua Yuan, Antony Ajan, Alexander S. Chernyshov, B. Ramamurthy Acharya
  • Patent number: 8889275
    Abstract: FePt-based heat assisted magnetic recording (HAMR) media comprising a thick granular FePt:C magnetic recording layer capable of maintaining a single layer film having desirable magnetic properties. According to one embodiment, the thick granular FePt:C magnetic recording layer comprises a plurality of carbon doped FePt alloy columnar grains, where the plurality of carbon doped FePt alloy columnar grains comprise a carbon gradient along the thickness of the hard magnetic recording layer.
    Type: Grant
    Filed: August 20, 2010
    Date of Patent: November 18, 2014
    Assignee: WD Media, LLC
    Inventors: Hua Yuan, Alexander Chernyshov, B. Ramamurthy Acharya
  • Patent number: 8867322
    Abstract: Systems and methods for providing thermal barrier bilayers for heat assisted magnetic recording (HAMR) media are provided. One such HAMR medium includes a substrate, a heat sink layer on the substrate, a thermal barrier bilayer on the heat sink layer, the bilayer comprising a first thermal barrier layer on the heat sink layer and an amorphous underlayer on the first thermal barrier layer, and a magnetic recording layer on the amorphous underlayer, wherein a thermal conductivity of the first thermal barrier layer is less than a thermal conductivity of the amorphous underlayer.
    Type: Grant
    Filed: July 1, 2013
    Date of Patent: October 21, 2014
    Assignee: WD Media, LLC
    Inventors: Alexander S. Chernyshov, Hua Yuan, Bincheng Wang, Tomoko Seki, Antony Ajan, B. Ramamurthy Acharya, Gerardo A. Bertero, David Treves
  • Publication number: 20140300994
    Abstract: Aspects of the present invention relate to a perpendicular magnetic recording (PMR) media stack and methods for fabricating the same. The PMR media stack has a novel grain isolation initiation layer (GIIL) and/or a novel exchange-break layer (EBL) that can improve the signal-to-noise performance of the PMR media stack. The PMR media stack includes a substrate, a soft underlayer on the substrate, an interlayer positioned on the soft underlayer, and a grain isolation initiation layer (GIIL) positioned on the interlayer, a magnetic layer positioned on the GIIL, and an exchange break layer (EBL) positioned on the magnetic layer. The GIIL and/or EBL includes a CoCrRu-oxide.
    Type: Application
    Filed: June 6, 2013
    Publication date: October 9, 2014
    Inventors: DAEHOON HONG, SY VU, KYONGHA KANG, B. RAMAMURTHY ACHARYA
  • Patent number: 8787124
    Abstract: Systems and methods for extracting a Curie temperature distribution in a heat assisted magnetic recording medium are provided. One such method involves saturating a magnetic recording medium by causing a laser to direct light on the medium and causing a magnet adjacent to the medium to generate a magnetic field on the medium, causing the magnet to remove the magnetic field on the medium, writing to the medium by causing the laser to direct light on the medium, recording measurements of light reflected from the medium made by a light detector, converting the measurements of reflected light into measurements of remanent thermal magnetization, and extracting the Curie temperature distribution from the measurements of remanent thermal magnetization. One such system involves a processor coupled to a spindle, a magnet, a laser, and a light detector, where the processor is configured to perform this method.
    Type: Grant
    Filed: December 10, 2013
    Date of Patent: July 22, 2014
    Assignee: WD Media, LLC
    Inventors: Alexander S. Chernyshov, Thanh V. Le, David Treves, Antony Ajan, B. Ramamurthy Acharya