Patents by Inventor Haiwen Xi

Haiwen Xi 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: 8750036
    Abstract: A memory unit includes a magnetic tunnel junction data cell electrically coupled to a bit line and a word line. The magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by passing a unipolar voltage across the magnetic tunnel junction data cell. A diode is electrically coupled between the magnetic tunnel junction data cell and the word line or bit line. A voltage source provides the unipolar voltage across the magnetic tunnel junction data cell that writes the high resistance state and the low resistance state.
    Type: Grant
    Filed: September 4, 2013
    Date of Patent: June 10, 2014
    Assignee: Seagate Technology, LLC
    Inventors: Xiaohua Lou, Haiwen Xi
  • Patent number: 8711608
    Abstract: A memory unit includes a giant magnetoresistance cell electrically coupled between a write bit line and a write source line. The giant magnetoresistance cell includes a free magnetic layer. A magnetic tunnel junction data cell is electrically coupled between a read bit line and a read source line. The magnetic tunnel junction data cell includes the free magnetic layer. A write current passes through the giant magnetoresistance cell to switch the giant magnetoresistance cell between a high resistance state and a low resistance state. The magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by magnetostatic coupling with the giant magnetoresistance cell, and be read by a read current passing though the magnetic tunnel junction data cell.
    Type: Grant
    Filed: March 5, 2013
    Date of Patent: April 29, 2014
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Hongyue Liu, Michael Xuefei Tang, Antoine Khoueir, Song S. Xue
  • Patent number: 8687413
    Abstract: A magnetic memory unit includes a tunneling barrier separating a free magnetic element and a reference magnetic element. A first phonon glass electron crystal layer is disposed on a side opposing the tunneling barrier of either the free magnetic element or the reference magnetic element. A second phonon glass electron crystal layer also be disposed on a side opposing the tunneling barrier of either the free magnetic element or the reference magnetic element to provide a Peltier effect on the free magnetic element and the reference magnetic element.
    Type: Grant
    Filed: February 28, 2013
    Date of Patent: April 1, 2014
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Haiwen Xi, Dimitar V. Dimitrov, Dexin Wang
  • 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
  • Patent number: 8679577
    Abstract: A magnetic tunnel junction cell having a free layer, a ferromagnetic pinned layer, and a barrier layer therebetween. The free layer has a central ferromagnetic portion and a stabilizing portion radially proximate the central ferromagnetic portion. The construction can be used for both in-plane magnetic memory cells where the magnetization orientation of the magnetic layer is in the stack film plane and out-of-plane magnetic memory cells where the magnetization orientation of the magnetic layer is out of the stack film plane, e.g., perpendicular to the stack plane.
    Type: Grant
    Filed: September 12, 2012
    Date of Patent: March 25, 2014
    Assignee: Seagate Technology LLC
    Inventors: Kaizhong Gao, Haiwen Xi
  • Patent number: 8670271
    Abstract: A magnetic tunnel junction having a ferromagnetic free layer and a ferromagnetic pinned reference layer, each having an out-of-plane magnetic anisotropy and an out-of-plane magnetization orientation, the ferromagnetic free layer switchable by spin torque. The magnetic tunnel junction includes a ferromagnetic assist layer proximate the free layer, the assist layer having a low magnetic anisotropy less than 700 Oe and positioned to apply a magnetic field on the free layer.
    Type: Grant
    Filed: April 5, 2013
    Date of Patent: March 11, 2014
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Zheng Gao, Wonjoon Jung, Xuebing Feng, Xiaohua Lou, Haiwen Xi
  • Patent number: 8659852
    Abstract: A magnetic junction memory array and methods of using the same are described. The magnetic junction memory array includes a plurality of electrically conductive word lines extending in a first direction, a plurality of electrically conductive bit lines extending in a second direction and forming a cross-point array with the plurality of electrically conductive word lines, and a memory cell proximate to, at least selected, cross-points forming a magnetic junction memory array. Each memory cell includes a magnetic pinned layer electrically between a magnetic bit and an isolation transistor. The isolation transistor has a current source and a gate. The current source is electrically coupled to the cross-point bit line and the gate is electrically coupled to the cross-point word line. An electrically conductive cover layer is disposed on and in electrical communication with the magnetic bits.
    Type: Grant
    Filed: April 21, 2008
    Date of Patent: February 25, 2014
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Song S. Xue
  • Patent number: 8659939
    Abstract: Spin torque magnetic memory elements that have a pinned layer, two free layers, and a current-blocking insulating layer proximate to at least one of the free layers. The resistive state (e.g., low resistance or high resistance) of the memory elements is altered by passing electric current through the element in one direction. In other words, to change from a low resistance to a high resistance, the direction of electric current is the same as to change from a high resistance to a low resistance. The elements have a unidirectional write scheme.
    Type: Grant
    Filed: June 22, 2012
    Date of Patent: February 25, 2014
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Dexin Wang, Dimitar V. Dimitrov, Paul E. Anderson, Song S. Xue
  • 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
  • Publication number: 20140003138
    Abstract: A memory unit includes a magnetic tunnel junction data cell electrically coupled to a bit line and a word line. The magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by passing a unipolar voltage across the magnetic tunnel junction data cell. A diode is electrically coupled between the magnetic tunnel junction data cell and the word line or bit line. A voltage source provides the unipolar voltage across the magnetic tunnel junction data cell that writes the high resistance state and the low resistance state.
    Type: Application
    Filed: September 4, 2013
    Publication date: January 2, 2014
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Xiaohua Lou, Haiwen Xi
  • Publication number: 20130329490
    Abstract: A method of switching the magnetization orientation of a ferromagnetic free layer of an out-of-plane magnetic tunnel junction cell, the method including: passing an AC switching current through the out-of-plane magnetic tunnel junction cell, wherein the AC switching current switches the magnetization orientation of the ferromagnetic free layer.
    Type: Application
    Filed: August 12, 2013
    Publication date: December 12, 2013
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Insik Jin, Xiaobin Wang, Yong Lu, Haiwen Xi
  • Patent number: 8599600
    Abstract: Write verify methods for resistance random access memory (RRAM) are provided. The methods include applying a reset operation voltage pulse across a RRAM cell to change a resistance of the RRAM cell from a low resistance state to a high resistance state and applying a forward resetting voltage pulse across the RRAM cell if the RRAM cell has a high resistance state resistance value less than a selected lower resistance limit value. The method also includes applying a reverse resetting voltage pulse across the RRAM cell if the RRAM cell has a high resistance state resistance values is greater than a selected upper resistance limit value. The reverse resetting voltage pulse has a second polarity being opposite the first polarity.
    Type: Grant
    Filed: October 21, 2011
    Date of Patent: December 3, 2013
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Song S. Xue
  • Publication number: 20130292784
    Abstract: An apparatus and method for enhancing data writing and retention to a magnetic memory element, such as in a non-volatile data storage array. In accordance with various embodiments, a programmable memory element has a reference layer and a storage layer. The reference layer is provided with a fixed magnetic orientation. The storage layer is programmed to have a first region with a magnetic orientation antiparallel to said fixed magnetic orientation, and a second region with a magnetic orientation parallel to said fixed magnetic orientation. A thermal assist layer may be incorporated into the memory element to enhance localized heating of the storage layer to aid in the transition of the first region from parallel to antiparallel magnetic orientation during a write operation.
    Type: Application
    Filed: July 3, 2013
    Publication date: November 7, 2013
    Inventors: Haiwen Xi, Yuankai Zheng, Xiaobin Wang, Dimitar V. Dimitrov, Pat J. Ryan
  • Patent number: 8541247
    Abstract: An apparatus and associated method for a non-volatile memory cell, such as an STRAM cell. In accordance with various embodiments, a magnetic free layer is laterally separated from an antiferromagnetic layer (AFM) by a non-magnetic spacer layer and medially separated from a synthetic antiferromagnetic layer (SAF) by a magnetic tunneling junction. The AFM pins the magnetization of the SAF through contact with a pinning region of the SAF that laterally extends beyond the magnetic tunneling junction.
    Type: Grant
    Filed: December 20, 2010
    Date of Patent: September 24, 2013
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Antoine Khoueir, Brian Lee, Patrick J. Ryan
  • Patent number: 8531876
    Abstract: A memory unit includes a magnetic tunnel junction data cell electrically coupled to a bit line and a word line. The magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by passing a unipolar voltage across the magnetic tunnel junction data cell. A diode is electrically coupled between the magnetic tunnel junction data cell and the word line or bit line. A voltage source provides the unipolar voltage across the magnetic tunnel junction data cell that writes the high resistance state and the low resistance state.
    Type: Grant
    Filed: June 20, 2012
    Date of Patent: September 10, 2013
    Assignee: Seagate Technology LLC
    Inventors: Xiaohua Lou, Haiwen Xi
  • Publication number: 20130228884
    Abstract: A magnetic tunnel junction having a ferromagnetic free layer and a ferromagnetic pinned reference layer, each having an out-of-plane magnetic anisotropy and an out-of-plane magnetization orientation, the ferromagnetic free layer switchable by spin torque. The magnetic tunnel junction includes a ferromagnetic assist layer proximate the free layer, the assist layer having a low magnetic anisotropy less than 700 Oe and positioned to apply a magnetic field on the free layer.
    Type: Application
    Filed: April 5, 2013
    Publication date: September 5, 2013
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Zheng Gao, Wonjoon Jung, Xuebing Feng, Xiaohue Lou, Haiwen Xi
  • 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
  • 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
  • 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
  • Patent number: 8519376
    Abstract: Nonvolatile resistive memory devices are disclosed. In some embodiments, the memory devices comprise multilayer structures including electrodes, one or more resistive storage layers, and separation layers. The separation layers insulate the resistive storage layers to prevent charge leakage from the storage layers and allow for the use of thin resistive storage layers. In some embodiments, the nonvolatile resistive memory device includes a metallic multilayer comprising two metallic layers about an interlayer. A dopant at an interface of the interlayer and metallic layers can provide a switchable electric field within the multilayer.
    Type: Grant
    Filed: October 27, 2009
    Date of Patent: August 27, 2013
    Assignee: Seagate Technology LLC
    Inventors: Dimitar Velikov Dimitrov, Insik Jin, Haiwen Xi