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: 8045366
    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: March 3, 2009
    Date of Patent: October 25, 2011
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Haiwen Xi, Kaizhong Gao, Olle Heinonen, Wenzhong Zhu
  • Publication number: 20110242883
    Abstract: Methods of writing to a multi-bit MRAM memory unit are described. The method includes to self-detected writing to a multi-bit (i.e., multilevel) thermally assisted MRAM. The self-detected writing increases a reading margin between data state levels and decreases reading margin variability due to cell resistance variation.
    Type: Application
    Filed: June 15, 2011
    Publication date: October 6, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Haiwen Xi
  • Publication number: 20110228597
    Abstract: Apparatus and associated method for writing data to a non-volatile memory cell, such as spin-torque transfer random access memory (STRAM). In accordance with some embodiments, a resistive sense element (RSE) has a heat assist region, magnetic tunneling junction (MTJ), and pinned region. When a first logical state is written to the MTJ with a spin polarized current, the pinned and heat assist regions each have a substantially zero net magnetic moment. When a second logical state is written to the MTJ with a static magnetic field, the pinned region has a substantially zero net magnetic moment and the heat assist region has a non-zero net magnetic moment.
    Type: Application
    Filed: May 27, 2011
    Publication date: September 22, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Xiaohua Lou, Haiwen Xi, Michael Xuefei Tang
  • Patent number: 8004883
    Abstract: Methods of writing to a multi-bit MRAM memory unit are described. The method includes to self-detected writing to a multi-bit (i.e., multilevel) thermally assisted MRAM. The self-detected writing increases a reading margin between data state levels and decreases reading margin variability due to cell resistance variation.
    Type: Grant
    Filed: May 18, 2010
    Date of Patent: August 23, 2011
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Haiwen Xi
  • Patent number: 8004874
    Abstract: Embodiments of the invention provide a multi-terminal resistance device with first and second electrodes, a shared third electrode, and a resistance layer providing first and second current paths between the shared third electrode and the first and second electrodes, respectively. A current state of the device may be programmed by applying one or more electrical signals along the first and/or second current paths to change a resistance of the device. In some embodiments, applying an electrical signal may switch a junction resistance of the first and/or second electrodes and the resistance layer between two or more resistance values. The device may include a shared fourth electrode to provide extra programming capability. In some embodiments, the device may be used to store a data state, to determine a count of multiple electrical signals, or to perform a logic operation between two electrical signals.
    Type: Grant
    Filed: March 27, 2009
    Date of Patent: August 23, 2011
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Kaizhong Gao, Song Xue
  • Patent number: 7999337
    Abstract: Apparatus and associated method for writing data to a non-volatile memory cell, such as spin-torque transfer random access memory (STRAM). In accordance with some embodiments, a resistive sense element (RSE) has a heat assist region, magnetic tunneling junction (MTJ), and pinned region. When a first logical state is written to the MTJ with a spin polarized current, the pinned and heat assist regions each have a substantially zero net magnetic moment. When a second logical state is written to the MTJ with a static magnetic field, the pinned region has a substantially zero net magnetic moment and the heat assist region has a non-zero net magnetic moment.
    Type: Grant
    Filed: July 13, 2009
    Date of Patent: August 16, 2011
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Xiaohua Lou, Haiwen Xi, Michael Xuefei Tang
  • Patent number: 7999338
    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: July 13, 2009
    Date of Patent: August 16, 2011
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Zheng Gao, Wenzhong Zhu, Wonjoon Jung, Haiwen Xi
  • Patent number: 8000128
    Abstract: A resistive random access memory (RRAM) cell that includes a first electrode having a lower portion, a continuous side portion and an upper portion, the lower portion and the continuous side portion having an outer surface and an inner surface; a resistive layer having a lower portion, a continuous side portion and an upper portion, the lower portion and the continuous side portion having an outer surface and an inner surface; and a second electrode having a lower portion, an upper portion and an outer surface; wherein the outer surface of the resistive layer directly contacts the inner surface of the first electrode.
    Type: Grant
    Filed: July 14, 2010
    Date of Patent: August 16, 2011
    Assignee: Seagate Technology LLC
    Inventors: Shaoping Li, Insik Jin, Zheng Gao, Eileen Yan, Kaizhong Gao, Haiwen Xi, Song Xue
  • Publication number: 20110194335
    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: Application
    Filed: April 19, 2011
    Publication date: August 11, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Haiwen Xi, Dimitar V. Dimitrov, Dexin Wang
  • Publication number: 20110194337
    Abstract: A method and apparatus for writing data to a non-volatile memory cell, such as a spin-torque transfer random access memory (STRAM) memory cell. In some embodiments, a selected resistive state is written to a magnetic tunneling structure by applying a succession of indeterminate write pulses thereto until the selected resistive state is verified.
    Type: Application
    Filed: April 21, 2011
    Publication date: August 11, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Xiaobin Wang, Yong Lu, Haiwen Xi, Yuankai Zheng, Yiran Chen, Harry Hongyue Liu, Dimitar Dimitrov, Wei Tian, Brian Seungwhan Lee
  • Publication number: 20110194343
    Abstract: Spin-transfer torque memory having a compensation element is disclosed. A spin-transfer torque memory unit includes a free magnetic layer having a magnetic easy axis and a magnetization orientation that can change direction due to spin-torque transfer when a write current passes through the spin-transfer torque memory unit; 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.
    Type: Application
    Filed: April 14, 2011
    Publication date: August 11, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Kaizhong Gao, Haiwen Xi, Wenzhong Zhu, Olle Heinonen
  • Publication number: 20110188300
    Abstract: A method and apparatus for stray magnetic field compensation in a non-volatile memory cell, such as a spin-torque transfer random access memory (STRAM). In some embodiments, a first tunneling barrier is coupled to a reference structure that has a perpendicular anisotropy and a first magnetization direction. A recording structure that has a perpendicular anisotropy is coupled to the first tunneling barrier and a nonmagnetic spacer layer. A compensation layer that has a perpendicular anisotropy and a second magnetization direction in substantial opposition to the first magnetization direction is coupled to the nonmagnetic spacer layer. Further, the memory cell is programmable to a selected resistance state with application of a current to the recording structure.
    Type: Application
    Filed: April 12, 2011
    Publication date: August 4, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Dimitar V. Dimitrov, Olle Gunnar Heinonen, Dexin Wang, Haiwen Xi
  • Publication number: 20110188293
    Abstract: A non-volatile memory cell and associated method is disclosed that includes a non-ohmic selection layer. In accordance with some embodiments, a non-volatile memory cell consists of a resistive sense element (RSE) coupled to a non-ohmic selection layer. The selection layer is configured to transition from a first resistive state to a second resistive state in response to a current greater than or equal to a predetermined threshold.
    Type: Application
    Filed: April 14, 2011
    Publication date: August 4, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Wei Tian, Insik Jin, Venugopalan Vaithyanathan, Haiwen Xi, Michael Xuefei Tang, Brian Lee
  • Publication number: 20110180888
    Abstract: A magnetic stack having a free layer having a switchable magnetization orientation, a reference layer having a pinned magnetization orientation, and a barrier layer therebetween. The stack includes an annular antiferromagnetic pinning layer electrically isolated from the free layer and in physical contact with the reference layer. In some embodiments, the reference layer is larger than the free layer.
    Type: Application
    Filed: April 11, 2011
    Publication date: July 28, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Antoine Khouier, Brian Lee, Pat Ryan, Michael Tang, Insik Jin, Paul E. Anderson
  • Publication number: 20110177621
    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: Application
    Filed: March 28, 2011
    Publication date: July 21, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Kaizhong Gao, Haiwen Xi
  • Publication number: 20110176360
    Abstract: Non-volatile magnetic random access memory (MRAM) devices that include magnetic flip-flop structures that include a magnetization controlling structure; a first tunnel barrier structure; and a magnetization controllable structure that includes a first polarizing layer; and a first stabilizing layer, wherein the first tunnel barrier structure is between the magnetization controllable structure and the magnetization controlling structure and the first polarizing layer is between the first stabilizing layer and the first tunnel barrier structure, wherein the magnetic flip-flop device has two stable overall magnetic configurations, and wherein a first unipolar current applied to the device will cause the orientation of the magnetization controlling structure to reverse its orientation and a second unipolar current applied to the electronic device will cause the magnetization controllable structure to switch its magnetization so that the device reaches one of the two stable overall magnetic configurations, wherein
    Type: Application
    Filed: March 29, 2011
    Publication date: July 21, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Dimitar V. Dimitrov, Olle Gunnar Heinonen, Yiran Chen, Haiwen Xi, Xiaohua Lou
  • Publication number: 20110169114
    Abstract: Electronic devices that include (i) a magnetization controlling structure; (ii) a tunnel barrier structure; and (iii) a magnetization controllable structure including: a first polarizing layer; and a first stabilizing layer, wherein the tunnel barrier structure is between the magnetization controlling structure and the magnetization controlling structure and the first polarizing layer is between the first stabilizing layer and the tunnel barrier structure, wherein the electronic device has two stable overall magnetic configurations, and wherein a first unipolar current applied to the electronic device will cause the orientation of the magnetization controlling structure to reverse its orientation and a second unipolar current applied to the electronic device will cause the magnetization controllable structure to switch its magnetization in order to obtain one of the two stable overall magnetic configurations, wherein the second unipolar current has an amplitude that is less than the first unipolar current.
    Type: Application
    Filed: March 24, 2011
    Publication date: July 14, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Dimitar V. Dimitrov, Olle Gunnar Heinonen, Yiran Chen, Haiwen Xi, Xiaohua Lou
  • Publication number: 20110170342
    Abstract: Electronic devices that include (i) a magnetization controlling structure; (ii) a tunnel barrier structure; and (iii) a magnetization controllable structure including: a first polarizing layer; and a first stabilizing layer, wherein the tunnel barrier structure is between the magnetization controlling structure and the magnetization controlling structure and the first polarizing layer is between the first stabilizing layer and the tunnel barrier structure, wherein the electronic device has two stable overall magnetic configurations, and wherein a first unipolar current applied to the electronic device will cause the orientation of the magnetization controlling structure to reverse its orientation and a second unipolar current applied to the electronic device will cause the magnetization controllable structure to switch its magnetization in order to obtain one of the two stable overall magnetic configurations, wherein the second unipolar current has an amplitude that is less than the first unipolar current.
    Type: Application
    Filed: March 24, 2011
    Publication date: July 14, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Dimitar V. Dimitrov, Olle Gunnar Heinonen, Yiran Chen, Haiwen Xi, Xiaohua Lou
  • Patent number: 7969771
    Abstract: Various embodiments of the present invention are generally directed to an apparatus and method associated with a semiconductor device with thermally coupled phase change layers. The semiconductor device comprises a first phase change layer selectively configurable in a relatively low resistance crystalline phase and a relatively high resistance amorphous phase, and a second phase change layer thermally coupled to the first phase change layer. The second phase change layer is characterized as a metal-insulator transition material. A programming pulse is applied to the semiconductor device from a first electrode layer to a second electrode layer to provide the first phase change layer with a selected resistance.
    Type: Grant
    Filed: September 30, 2008
    Date of Patent: June 28, 2011
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Michael Xuefei Tang, Yuankai Zheng, Patrick Ryan
  • Publication number: 20110149641
    Abstract: Apparatus and associated method for writing data to a non-volatile memory cell, such as spin-torque transfer random access memory (STRAM). In accordance with some embodiments, a resistive sense element (RSE) has a heat assist region, magnetic tunneling junction (MTJ), and pinned region. When a first logical state is written to the MTJ with a spin polarized current, the pinned and heat assist regions each have a substantially zero net magnetic moment. When a second logical state is written to the MTJ with a static magnetic field, the pinned region has a substantially zero net magnetic moment and the heat assist region has a non-zero net magnetic moment.
    Type: Application
    Filed: March 3, 2011
    Publication date: June 23, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Xiaohua Lou, Haiwen Xi, Michael Xuefei Tang