Patents by Inventor Wenzhong Zhu

Wenzhong Zhu 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).

  • Perpendicular Magnetic Recording Media with Magnetic Anisotropy Gradient and Local Exchange Coupling
    Publication number: 20150170697
    Abstract: A perpendicular magnetic recording medium adapted for high recording density and high data recording rate comprises a non-magnetic substrate having at least one surface with a layer stack formed thereon, the layer stack including a perpendicular recording layer containing a plurality of columnar-shaped magnetic grains extending perpendicularly to the substrate surface for a length, with a first end distal the surface and a second end proximal the surface, wherein each of the magnetic grains has: (1) a gradient of perpendicular magnetic coercivity Hk extending along its length between the first end and second ends; and (2) predetermined local exchange coupling strengths along the length.
    Type: Application
    Filed: February 24, 2015
    Publication date: June 18, 2015
    Inventors: Shaoping Li, Kaizhong Gao, Lei Wang, Wenzhong Zhu, Xiaobin Wang
  • Perpendicular magnetic recording media with magnetic anisotropy gradient and local exchange coupling
    Patent number: 8962164
    Abstract: A perpendicular magnetic recording medium adapted for high recording density and high data recording rate comprises a non-magnetic substrate having at least one surface with a layer stack formed thereon, the layer stack including a perpendicular recording layer containing a plurality of columnar-shaped magnetic grains extending perpendicularly to the substrate surface for a length, with a first end distal the surface and a second end proximal the surface, wherein each of the magnetic grains has: (1) a gradient of perpendicular magnetic anisotropy field Hk extending along its length between the first end and second ends; and (2) predetermined local exchange coupling strengths along the length.
    Type: Grant
    Filed: August 6, 2013
    Date of Patent: February 24, 2015
    Assignee: Seagate Technology LLC
    Inventors: Shaoping Li, Kaizhong Gao, Lei Wang, Wenzhong Zhu, Xiaobin Wang
  • Magnetic stack with oxide to reduce switching current
    Patent number: 8686524
    Abstract: A magnetic stack having a ferromagnetic free layer, a metal oxide layer that is antiferromagnetic at a first temperature and non-magnetic at a second temperature higher than the first temperature, a ferromagnetic pinned reference layer, and a non-magnetic spacer layer between the free layer and the reference layer. During a writing process, the metal oxide layer is non-magnetic. For magnetic memory cells, such as magnetic tunnel junction cells, the metal oxide layer provides reduced switching currents.
    Type: Grant
    Filed: June 8, 2012
    Date of Patent: April 1, 2014
    Assignee: Seagate Technology LLC
    Inventors: Xiaohua Lou, Yuankai Zheng, Wenzhong Zhu, Wei Tian, Zheng Gao
  • STRAM with composite free magnetic element
    Patent number: 8681539
    Abstract: Spin-transfer torque memory includes a composite free magnetic element, a reference magnetic element having a magnetization orientation that is pinned in a reference direction, and an electrically insulating and non-magnetic tunneling barrier layer separating the composite free magnetic element from the magnetic reference element. The free magnetic element includes a hard magnetic layer exchanged coupled to a soft magnetic layer. The composite free magnetic element has a magnetization orientation that can change direction due to spin-torque transfer when a write current passes through the spin-transfer torque memory unit.
    Type: Grant
    Filed: April 15, 2013
    Date of Patent: March 25, 2014
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Haiwen Xi, Kaizhong Gao, Olle Heinonen, Wenzhong Zhu
  • RANDOM BIT GENERATOR WITH MAGNETIC TUNNEL JUNCTION
    Publication number: 20140022837
    Abstract: Devices and methods for generating a random number that utilizes a magnetic tunnel junction are disclosed. An AC current source can be in electrical connection to a magnetic tunnel junction to provide an AC current to the magnetic tunnel junction. A read circuit can be used to determine a bit based on a state of the magnetic tunnel junction. A rate of production of the bits can be adjusted, such as by adjusting a frequency or amplitude of the AC current. A probability of obtaining a “0” or “1” bit can be managed, such as by an addition of DC biasing to the AC current.
    Type: Application
    Filed: July 22, 2013
    Publication date: January 23, 2014
    Applicant: Seagate Technology LLC
    Inventors: Xiaobin Wang, Wenzhong Zhu, Henry Huang, Yiran Chen, Haiwen Xi
  • Magnetic memory with asymmetric energy barrier
    Patent number: 8634223
    Abstract: A magnetic tunnel junction memory cell includes a ferromagnetic reference layer, a ferromagnetic free layer, and a non-magnetic barrier layer separating the ferromagnetic reference layer from the ferromagnetic free layer. The magnetic tunnel junction cell has an asymmetric energy barrier for switching between a high resistance data state and a low resistance data state. Memory devices and methods are also described.
    Type: Grant
    Filed: April 13, 2012
    Date of Patent: January 21, 2014
    Assignee: Seagate Technology LLC
    Inventors: Wenzhong Zhu, Xiaohua Lou, Dimitar V. Dimitrov
  • Perpendicular Magnetic Recording Media with Magnetic Anisotropy Gradient and Local Exchange Coupling
    Publication number: 20140011053
    Abstract: A perpendicular magnetic recording medium adapted for high recording density and high data recording rate comprises a non-magnetic substrate having at least one surface with a layer stack formed thereon, the layer stack including a perpendicular recording layer containing a plurality of columnar-shaped magnetic grains extending perpendicularly to the substrate surface for a length, with a first end distal the surface and a second end proximal the surface, wherein each of the magnetic grains has: (1) a gradient of perpendicular magnetic anisotropy field Hk extending along its length between the first end and second ends; and (2) predetermined local exchange coupling strengths along the length.
    Type: Application
    Filed: August 6, 2013
    Publication date: January 9, 2014
    Applicant: Seagate Technology LLC
    Inventors: Shaoping Li, Kaizhong Gao, Lei Wang, Wenzhong Zhu, Xiaobin Wang
  • STRAM WITH COMPOSITE FREE MAGNETIC ELEMENT
    Publication number: 20130229862
    Abstract: Spin-transfer torque memory includes a composite free magnetic element, a reference magnetic element having a magnetization orientation that is pinned in a reference direction, and an electrically insulating and non-magnetic tunneling barrier layer separating the composite free magnetic element from the magnetic reference element. The free magnetic element includes a hard magnetic layer exchanged coupled to a soft magnetic layer. The composite free magnetic element has a magnetization orientation that can change direction due to spin-torque transfer when a write current passes through the spin-transfer torque memory unit.
    Type: Application
    Filed: April 15, 2013
    Publication date: September 5, 2013
    Applicant: SEGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Haiwen Xi, Kaizhong Gao, Olle Heinonen, Wenzhong Zhu
  • Quiescent testing of non-volatile memory array
    Patent number: 8526252
    Abstract: A method and apparatus for testing an array of non-volatile memory cells, such as a spin-torque transfer random access memory (STRAM). In some embodiments, an array of memory cells having a plurality of unit cells with a resistive sense element and a switching device has a row decoder and a column decoder connected to the plurality of unit cells. A test circuitry sends a non-operational test pattern through the array via the row and column decoders with a quiescent supply current to identify defects in the array of memory cells.
    Type: Grant
    Filed: March 17, 2009
    Date of Patent: September 3, 2013
    Assignee: Seagate Technology LLC
    Inventors: Hai Li, Yiran Chen, Alan Xuguang Wang, Haiwen Xi, Wenzhong Zhu, Andreas K. Roelofs
  • Spatial correlation of reference cells in resistive memory array
    Patent number: 8526215
    Abstract: The present disclosure relates to methods of selectively placing a reference column or reference row in a memory array. The method includes measuring a resistance state resistance value for a plurality of variable resistive memory cells within a memory array and mapping a location of each measured variable resistive memory cell to form a map of the resistance state resistance values for a plurality of variable resistive memory cells within a memory array. Then a column or row is selected to be a reference column or reference row based on the map of the resistance state resistance value for a plurality of variable resistive memory cells within a memory array, to minimize read operation errors, and forming a variable resistive memory cell memory array.
    Type: Grant
    Filed: March 2, 2012
    Date of Patent: September 3, 2013
    Assignee: Seagate Technology LLC
    Inventors: Yiran Chen, Hai Li, Wenzhong Zhu, Xiaobin Wang, Henry Huang, Hongyue Liu
  • Magnetic stack having reference layers with orthogonal magnetization orientation directions
    Patent number: 8519498
    Abstract: A magnetic cell includes a ferromagnetic free layer having a free magnetization orientation direction and a first ferromagnetic pinned reference layer having a first reference magnetization orientation direction that is parallel or anti-parallel to the free magnetization orientation direction. A first oxide barrier layer is between the ferromagnetic free layer and the first ferromagnetic pinned reference layer. The magnetic cell further includes a second ferromagnetic pinned reference layer having a second reference magnetization orientation direction that is orthogonal to the first reference magnetization orientation direction. The ferromagnetic free layer is between the first ferromagnetic pinned reference layer and the second ferromagnetic pinned reference layer.
    Type: Grant
    Filed: September 13, 2012
    Date of Patent: August 27, 2013
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Zheng Gao, Wenzhong Zhu, Wonjoon Jung, Haiwen Xi
  • STRAM with compensation element and method of making the same
    Patent number: 8508005
    Abstract: A spin-transfer torque memory unit includes a free magnetic layer having a magnetic easy axis; a reference magnetic element having a magnetization orientation that is pinned in a reference direction; an electrically insulating and non-magnetic tunneling barrier layer separating the free magnetic layer from the magnetic reference element; and a compensation element adjacent to the free magnetic layer. The compensation element applies a bias field on the magnetization orientation of the free magnetic layer. The bias field is formed of a first vector component parallel to the easy axis of the free magnetic layer and a second vector component orthogonal to the easy axis of the free magnetic layer. The bias field reduces a write current magnitude required to switch the direction of the magnetization orientation of the free magnetic layer.
    Type: Grant
    Filed: May 22, 2012
    Date of Patent: August 13, 2013
    Assignee: Seagate Technology LLC
    Inventors: Kaizhong Gao, Haiwen Xi, Wenzhong Zhu, Olle Heinonen
  • Perpendicular magnetic recording media with magnetic anisotropy gradient and local exchange coupling
    Patent number: 8501330
    Abstract: A perpendicular magnetic recording medium adapted for high recording density and high data recording rate comprises a non-magnetic substrate having at least one surface with a layer stack formed thereon, the layer stack including a perpendicular recording layer containing a plurality of columnar-shaped magnetic grains extending perpendicularly to the substrate surface for a length, with a first end distal the surface and a second end proximal the surface, wherein each of the magnetic grains has: (1) a gradient of perpendicular magnetic anisotropy field Hk extending along its length between the first end and second ends; and (2) predetermined local exchange coupling strengths along the length.
    Type: Grant
    Filed: October 11, 2011
    Date of Patent: August 6, 2013
    Assignee: Seagate Technology LLC
    Inventors: Shaoping Li, Kaizhong Gao, Lei Wang, Wenzhong Zhu, Xiaobin Wang
  • Tunable random bit generator with magnetic tunnel junction
    Patent number: 8495118
    Abstract: A random number generator device that utilizes a magnetic tunnel junction. An AC current source is in electrical connection to the magnetic tunnel junction to provide an AC current having an amplitude and a frequency through the free layer of the magnetic tunnel junction, the AC current configured to switch the magnetization orientation of the free layer via thermal magnetization. A read circuit is used to determine the relative orientation of the free layer magnetization in relation to the reference layer magnetization orientation.
    Type: Grant
    Filed: March 6, 2009
    Date of Patent: July 23, 2013
    Assignee: Seagate Technology LLC
    Inventors: Xiaobin Wang, Wenzhong Zhu, Henry Huang, Yiran Chen, Haiwen Xi
  • Pulse writing for bit patterned and continuous media recording
    Patent number: 8477443
    Abstract: Data storage systems are provided. Data storage systems illustratively include a writing element and a recording medium. In some embodiments, the writing element generates first and second magnetization fields that respectively record first and second magnetization patterns to the recording medium. In some embodiments, the writing element is de-saturated between recording the first and second magnetization patterns.
    Type: Grant
    Filed: July 21, 2009
    Date of Patent: July 2, 2013
    Assignee: Seagate Technology LLC
    Inventors: Kaizhong Gao, Olle Gunnar Heinonen, Jianhua Xue, Wenzhong Zhu
  • Magnetic stack with oxide to reduce switching current
    Patent number: 8426222
    Abstract: A magnetic stack having a ferromagnetic free layer, a metal oxide layer that is antiferromagnetic at a first temperature and non-magnetic at a second temperature higher than the first temperature, a ferromagnetic pinned reference layer, and a non-magnetic spacer layer between the free layer and the reference layer. During a writing process, the metal oxide layer is non-magnetic. For magnetic memory cells, such as magnetic tunnel junction cells, the metal oxide layer provides reduced switching currents.
    Type: Grant
    Filed: September 29, 2011
    Date of Patent: April 23, 2013
    Assignee: Seagate Technology LLC
    Inventors: Xiaohua Lou, Yuankai Zheng, Wenzhong Zhu, Wei Tian, Zheng Gao
  • STRAM with composite free magnetic element
    Patent number: 8422279
    Abstract: Spin-transfer torque memory includes a composite free magnetic element, a reference magnetic element having a magnetization orientation that is pinned in a reference direction, and an electrically insulating and non-magnetic tunneling barrier layer separating the composite free magnetic element from the magnetic reference element. The free magnetic element includes a hard magnetic layer exchanged coupled to a soft magnetic layer. The composite free magnetic element has a magnetization orientation that can change direction due to spin-torque transfer when a write current passes through the spin-transfer torque memory unit.
    Type: Grant
    Filed: October 21, 2011
    Date of Patent: April 16, 2013
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Haiwen Xi, Kaizhong Gao, Olle Heinonen, Wenzhong Zhu
  • Field assisted switching of a magnetic memory element
    Patent number: 8422277
    Abstract: Method and apparatus for writing data to a magnetic memory element, such as a spin-torque transfer random access memory (STRAM) memory cell. In accordance with various embodiments, a write current is applied through a magnetic memory element to initiate magnetic precession of the element to a desired magnetic state. A flow of a field assist current is subsequently initiated adjacent the magnetic memory element during continued application of the write current to induce a magnetic field upon the element. The field assist current persists after the write current is terminated to provide field assisted precession to the desired magnetic state.
    Type: Grant
    Filed: November 4, 2010
    Date of Patent: April 16, 2013
    Assignee: Seagate Technology LLC
    Inventors: Xin Cao, Haiwen Xi, Wenzhong Zhu, Robert Lamberton, Kaizhong Gao
  • Magnetic tunnel junction and memristor apparatus
    Patent number: 8391055
    Abstract: A magnetic memory device includes a magnetic tunnel junction having a free magnetic layer having a magnetization orientation that is switchable between a high resistance state magnetization orientation and a low resistance state magnetization orientation and a memristor solid state element electrically coupled to the magnetic tunnel junction. The memristor has a device response that is an integrated voltage versus an integrated current.
    Type: Grant
    Filed: September 23, 2011
    Date of Patent: March 5, 2013
    Assignee: Seagate Technology LLC
    Inventors: Xiaobin Wang, Yiran Chen, Alan Wang, Haiwen Xi, Wenzhong Zhu, Hai Li, Hongyue Liu
  • MAGNETIC STACK HAVING REFERENCE LAYERS WITH ORTHOGONAL MAGNETIZATION ORIENTATION DIRECTIONS
    Publication number: 20130001720
    Abstract: A magnetic cell includes a ferromagnetic free layer having a free magnetization orientation direction and a first ferromagnetic pinned reference layer having a first reference magnetization orientation direction that is parallel or anti-parallel to the free magnetization orientation direction. A first oxide barrier layer is between the ferromagnetic free layer and the first ferromagnetic pinned reference layer. The magnetic cell further includes a second ferromagnetic pinned reference layer having a second reference magnetization orientation direction that is orthogonal to the first reference magnetization orientation direction. The ferromagnetic free layer is between the first ferromagnetic pinned reference layer and the second ferromagnetic pinned reference layer.
    Type: Application
    Filed: September 13, 2012
    Publication date: January 3, 2013
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Zheng Gao, Wenzhong Zhu, Wonjoon Jung, Haiwen Xi