Patents by Inventor Guohan Hu

Guohan Hu 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: 8866207
    Abstract: A magnetic tunnel junction (MTJ) includes a magnetic free layer, having a variable magnetization direction; an insulating tunnel barrier located adjacent to the free layer; a magnetic fixed layer having an invariable magnetization direction, the fixed layer disposed adjacent the tunnel barrier such that the tunnel barrier is located between the free layer and the fixed layer, wherein the free layer and the fixed layer have perpendicular magnetic anisotropy; and one or more of: a composite fixed layer, the composite fixed layer comprising a dusting layer, a spacer layer, and a reference layer; a synthetic antiferromagnetic (SAF) fixed layer structure, the SAF fixed layer structure comprising a SAF spacer located between the fixed layer and a second fixed magnetic layer; and a dipole layer, wherein the free layer is located between the dipole layer and the tunnel barrier.
    Type: Grant
    Filed: September 4, 2012
    Date of Patent: October 21, 2014
    Assignee: International Business Machines Corporation
    Inventors: Guohan Hu, Janusz J. Nowak, Philip L. Trouilloud, Daniel C. Worledge
  • Patent number: 8767446
    Abstract: A magneto resistive random access memory system includes a first magnetic-tunnel-junction device coupled to a first bit-line, a second magnetic-tunnel-junction device coupled to a second bit-line, a selection transistor coupled to the first and second bit-lines and a word-line coupled to the selection transistor.
    Type: Grant
    Filed: October 12, 2011
    Date of Patent: July 1, 2014
    Assignee: International Business Machines Corporation
    Inventors: Guohan Hu, Yu Lu
  • Publication number: 20140169080
    Abstract: A thermal spin torque transfer magnetoresistive random access memory (MRAM) apparatus includes a magnetic tunnel junction and a tunnel junction programming circuit. The magnetic tunnel junction includes a reference layer having a fixed magnetic polarity, a tunnel barrier layer, and a free layer on an opposite side of the tunnel barrier layer from the reference layer. The free layer includes a first layer having a first Curie temperature and a second layer having a second Curie temperature different from the first Curie temperature. The tunnel junction programming circuit is configured to apply a current through the magnetic tunnel junction to generate a write temperature in the magnetic tunnel junction and to write to the free layer of the magnetic tunnel junction.
    Type: Application
    Filed: December 17, 2012
    Publication date: June 19, 2014
    Applicant: International Business Machines Corporation
    Inventors: Daniel C. Worledge, Guohan Hu
  • Publication number: 20140169082
    Abstract: A thermal spin torque transfer magnetoresistive random access memory (MRAM) apparatus includes a magnetic tunnel junction and a tunnel junction programming circuit. The magnetic tunnel junction includes a reference layer having a fixed magnetic polarity, a tunnel barrier layer, and a free layer on an opposite side of the tunnel barrier layer from the reference layer. The free layer includes a first layer having a first Curie temperature and a second layer having a second Curie temperature different from the first Curie temperature. The tunnel junction programming circuit is configured to apply a current through the magnetic tunnel junction to generate a write temperature in the magnetic tunnel junction and to write to the free layer of the magnetic tunnel junction.
    Type: Application
    Filed: August 16, 2013
    Publication date: June 19, 2014
    Applicant: International Business Machines Corporation
    Inventors: Daniel C. Worledge, Guohan Hu
  • Patent number: 8717808
    Abstract: Magnetic devices, magnetoresistive structures, and methods and techniques associated with the magnetic devices and magnetoresistive structures are presented. For example, a magnetic device is presented. The magnetic device includes a ferromagnet, an antiferromagnet coupled to the ferromagnet, and a nonmagnetic metal proximate to the ferromagnet. The antiferromagnet provides uniaxial anisotropy to the magnetic device. A resistance of the nonmagnetic metal is dependent upon a direction of a magnetic moment of the ferromagnet.
    Type: Grant
    Filed: June 6, 2012
    Date of Patent: May 6, 2014
    Assignee: International Business Machines Corporation
    Inventors: Guohan Hu, Jonathan Z. Sun
  • Patent number: 8492859
    Abstract: A magnetic tunnel junction (MTJ) includes first and second magnetic layers; a tunnel barrier located between the first and second magnetic layers; a first spacer layer located between the first magnetic layer and the tunnel barrier, the first spacer layer comprising a non-magnetic material; and a first interfacial layer located between the first spacer layer and the tunnel barrier.
    Type: Grant
    Filed: February 15, 2011
    Date of Patent: July 23, 2013
    Assignee: International Business Machines Corporation
    Inventor: Guohan Hu
  • Patent number: 8456894
    Abstract: A mechanism is provided for noncontact writing. Multiple magnetic islands are provided on a nonmagnetic layer. A reference layer is provided under the nonmagnetic layer. A spin-current is caused to write a state to a magnetic island of the multiple magnetic islands by moving a heat source to heat the magnetic island.
    Type: Grant
    Filed: May 3, 2011
    Date of Patent: June 4, 2013
    Assignee: International Business Machines Corporation
    Inventors: David W. Abraham, Jonathan Z. Sun, Guohan Hu
  • Publication number: 20130094282
    Abstract: A magneto resistive random access memory system includes a first magnetic-tunnel-junction device coupled to a first bit-line, a second magnetic-tunnel-junction device coupled to a second bit-line, a selection transistor coupled to the first and second bit-lines and a word-line coupled to the selection transistor.
    Type: Application
    Filed: October 12, 2011
    Publication date: April 18, 2013
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Guohan Hu, Yu Lu
  • Patent number: 8406040
    Abstract: A magnetic tunnel junction stack including a pinned magnetic layer, a tunnel barrier layer formed of magnesium oxide (MgO), a free magnetic layer adjacent to the tunnel barrier layer, and a layer of vanadium (V) adjacent to the free magnetic layer.
    Type: Grant
    Filed: January 8, 2010
    Date of Patent: March 26, 2013
    Assignee: International Business Machines Corporation
    Inventors: Daniel C. Worledge, Guohan Hu, Jonathan Z. Sun
  • Publication number: 20130005051
    Abstract: A magnetic tunnel junction (MTJ) includes a magnetic free layer, having a variable magnetization direction; an insulating tunnel barrier located adjacent to the free layer; a magnetic fixed layer having an invariable magnetization direction, the fixed layer disposed adjacent the tunnel barrier such that the tunnel barrier is located between the free layer and the fixed layer, wherein the free layer and the fixed layer have perpendicular magnetic anisotropy; and one or more of: a composite fixed layer, the composite fixed layer comprising a dusting layer, a spacer layer, and a reference layer; a synthetic antiferromagnetic (SAF) fixed layer structure, the SAF fixed layer structure comprising a SAF spacer located between the fixed layer and a second fixed magnetic layer; and a dipole layer, wherein the free layer is located between the dipole layer and the tunnel barrier.
    Type: Application
    Filed: September 4, 2012
    Publication date: January 3, 2013
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Guohan Hu, Janusz J. Nowak, Philip L. Trouilloud, Daniel C. Worledge
  • Publication number: 20130005052
    Abstract: A magnetic tunnel junction (MTJ) for a magnetic random access memory (MRAM) includes a magnetic free layer having a variable magnetization direction; an iron (Fe) dusting layer formed on the free layer; an insulating tunnel barrier formed on the dusting layer; and a magnetic fixed layer having an invariable magnetization direction, disposed adjacent the tunnel barrier such that the tunnel barrier is located between the free layer and the fixed layer; wherein the free layer and the fixed layer have perpendicular magnetic anisotropy and are magnetically coupled through the tunnel barrier.
    Type: Application
    Filed: September 5, 2012
    Publication date: January 3, 2013
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Guohan Hu, Janusz J. Nowak, Philip L. Trouilloud, Daniel C. Worledge
  • Publication number: 20120329177
    Abstract: Magnetoresistive structures, devices, memories, and methods for forming the same are presented. For example, a magnetoresistive structure includes a ferromagnetic layer, a ferrimagnetic layer coupled to the ferromagnetic layer, a pinned layer and a nonmagnetic spacer layer. A free side of the magnetoresistive structure comprises the ferromagnetic layer and the ferrimagnetic layer. The nonmagnetic spacer layer is at least partly between the free side and the pinned layer. A saturation magnetization of the ferromagnetic layer opposes a saturation magnetization of the ferrimagnetic layer. The nonmagnetic spacer layer may include a tunnel barrier layer, such as one composed of magnesium oxide (MgO), or a nonmagnetic metal layer.
    Type: Application
    Filed: September 4, 2012
    Publication date: December 27, 2012
    Applicant: International Business Machines Corporation
    Inventors: David William Abraham, Guohan Hu, Jonathan Zanhong Sun, Daniel Christopher Worledge
  • Publication number: 20120281460
    Abstract: A mechanism is provided for noncontact writing. Multiple magnetic islands are provided on a nonmagnetic layer. A reference layer is provided under the nonmagnetic layer. A spin-current is caused to write a state to a magnetic island of the multiple magnetic islands by moving a heat source to heat the magnetic island.
    Type: Application
    Filed: May 3, 2011
    Publication date: November 8, 2012
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: David W. Abraham, Jonathan Z. Sun, Guohan Hu
  • Publication number: 20120267733
    Abstract: A magnetic tunnel junction (MTJ) includes a magnetic free layer, having a variable magnetization direction; an insulating tunnel barrier located adjacent to the free layer; a magnetic fixed layer having an invariable magnetization direction, the fixed layer disposed adjacent the tunnel barrier such that the tunnel barrier is located between the free layer and the fixed layer, wherein the free layer and the fixed layer have perpendicular magnetic anisotropy; and one or more of: a composite fixed layer, the composite fixed layer comprising a dusting layer, a spacer layer, and a reference layer; a synthetic antiferromagnetic (SAF) fixed layer structure, the SAF fixed layer structure comprising a SAF spacer located between the fixed layer and a second fixed magnetic layer; and a dipole layer, wherein the free layer is located between the dipole layer and the tunnel barrier.
    Type: Application
    Filed: April 25, 2011
    Publication date: October 25, 2012
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Guohan Hu, Janusz J. Nowak, Philip L. Troilloud, Daniel C. Worledge
  • Patent number: 8283741
    Abstract: A magnetic tunnel junction stack that includes a pinned magnetic layer, a tunnel barrier layer formed of magnesium oxide (MgO), and a free magnetic layer formed adjacent to the tunnel barrier layer and of a material having a magnetization perpendicular to an MgO interface of the tunnel barrier layer and with a magnetic moment per unit area within a factor of 2 of approximately 2 nanometers (nm)×300 electromagnetic units per cubic centimeter (emu/cm3).
    Type: Grant
    Filed: January 8, 2010
    Date of Patent: October 9, 2012
    Assignee: International Business Machines Corporation
    Inventors: Guohan Hu, Jonathan Z. Sun, Daniel Christopher Worledge
  • Patent number: 8284594
    Abstract: Magnetic devices, magnetoresistive structures, and methods and techniques associated with the magnetic devices and magnetoresistive structures are presented. For example, a magnetic device is presented. The magnetic device includes a ferromagnet, an antiferromagnet coupled to the ferromagnet, and a nonmagnetic metal proximate to the ferromagnet. The antiferromagnet provides uniaxial anisotropy to the magnetic device. A resistance of the nonmagnetic metal is dependent upon a direction of a magnetic moment of the ferromagnet.
    Type: Grant
    Filed: September 3, 2009
    Date of Patent: October 9, 2012
    Assignee: International Business Machines Corporation
    Inventors: Guohan Hu, Jonathan Zanghong Sun
  • Publication number: 20120241878
    Abstract: A magnetic tunnel junction (MTJ) for a magnetic random access memory (MRAM) includes a magnetic free layer having a variable magnetization direction; an iron (Fe) dusting layer formed on the free layer; an insulating tunnel barrier formed on the dusting layer; and a magnetic fixed layer having an invariable magnetization direction, disposed adjacent the tunnel barrier such that the tunnel barrier is located between the free layer and the fixed layer; wherein the free layer and the fixed layer have perpendicular magnetic anisotropy and are magnetically coupled through the tunnel barrier.
    Type: Application
    Filed: March 24, 2011
    Publication date: September 27, 2012
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Guohan Hu, Janusz J. Nowak, Philip L. Trouilloud, Daniel C. Worledge
  • Publication number: 20120241885
    Abstract: Magnetic devices, magnetoresistive structures, and methods and techniques associated with the magnetic devices and magnetoresistive structures are presented. For example, a magnetic device is presented. The magnetic device includes a ferromagnet, an antiferromagnet coupled to the ferromagnet, and a nonmagnetic metal proximate to the ferromagnet. The antiferromagnet provides uniaxial anisotropy to the magnetic device. A resistance of the nonmagnetic metal is dependent upon a direction of a magnetic moment of the ferromagnet.
    Type: Application
    Filed: June 6, 2012
    Publication date: September 27, 2012
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Guohan Hu, Jonathan Zanghong Sun
  • Publication number: 20120205759
    Abstract: A magnetic tunnel junction (MTJ) includes first and second magnetic layers; a tunnel barrier located between the first and second magnetic layers; a first spacer layer located between the first magnetic layer and the tunnel barrier, the first spacer layer comprising a non-magnetic material; and a first interfacial layer located between the first spacer layer and the tunnel barrier.
    Type: Application
    Filed: February 15, 2011
    Publication date: August 16, 2012
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventor: Guohan Hu
  • Publication number: 20110169111
    Abstract: A magnetic tunnel junction stack that includes a pinned magnetic layer, a tunnel barrier layer formed of magnesium oxide (MgO), and a free magnetic layer formed adjacent to the tunnel barrier layer and of a material having a magnetization perpendicular to an MgO interface of the tunnel barrier layer and with a magnetic moment per unit area within a factor of 2 of approximately 2 nanometers (nm)×300 electromagnetic units per cubic centimeter (emu/cm3).
    Type: Application
    Filed: January 8, 2010
    Publication date: July 14, 2011
    Applicant: INTERNATIONAL BUSINESS MACHINES CORPORATION
    Inventors: Guohan Hu, Jonathan Z. Sun, Daniel C. Worledge