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: 8223532
    Abstract: Memory units that have a magnetic tunnel junction cell that utilizes spin torque and a current induced magnetic field to assist in the switching of the magnetization orientation of the free layer of the magnetic tunnel junction cell. The memory unit includes a spin torque current source for passing a current through the magnetic tunnel junction cell, the spin torque current source having a direction perpendicular to the magnetization orientations, and also includes a magnetic ampere field current source is oriented in a direction orthogonal or at some angles to the magnetization orientations.
    Type: Grant
    Filed: August 27, 2008
    Date of Patent: July 17, 2012
    Assignee: Seagate Technology LLC
    Inventors: Xiaobin Wang, Haiwen Xi, Hongyue Liu, Insik Jin, Andreas Roelofs, Eileen Yan, Dimitar V. Dimitrov
  • Patent number: 8218356
    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 7, 2010
    Date of Patent: July 10, 2012
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Dexin Wang, Dimitar V. Dimitrov, Paul E. Anderson, Song S. Xue
  • Publication number: 20120153413
    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: Application
    Filed: December 20, 2010
    Publication date: June 21, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Antoine Khoueir, Brian Lee, Patrick J. Ryan
  • Patent number: 8203870
    Abstract: An apparatus and associated method for a non-volatile memory cell, such as a multi-bit magnetic random access memory cell. In accordance with various embodiments, a first magnetic tunnel junction (MTJ) is adjacent to a second MTJ having a magnetic filter. The first MTJ is programmed to a first logical state with a first magnetic flux while the magnetic filter absorbs the first magnetic flux to prevent the second MTJ from being programmed.
    Type: Grant
    Filed: November 23, 2010
    Date of Patent: June 19, 2012
    Assignee: Seagate Technology LLC
    Inventors: Nurul Amin, Dimitar V. Dimitrov, Haiwen Xi, Song S. Xue
  • Patent number: 8203865
    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: Grant
    Filed: April 14, 2011
    Date of Patent: June 19, 2012
    Assignee: Seagate Technology LLC
    Inventors: Wei Tian, Insik Jin, Venugopalan Vaithyanathan, Haiwen Xi, Michael Xuefei Tang, Brian Lee
  • Patent number: 8203192
    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: Grant
    Filed: April 14, 2011
    Date of Patent: June 19, 2012
    Assignee: Seagate Technology LLC
    Inventors: Kaizhong Gao, Haiwen Xi, Wenzhong Zhu, Olle Heinonen
  • Patent number: 8199562
    Abstract: An apparatus and method for enhancing read and write sense margin in a memory cell having a resistive sense element (RSE), such as but not limited to a resistive random access memory (RRAM) element or a spin-torque transfer random access memory (STRAM) element. The RSE has a hard programming direction and an easy programming direction. A write current is applied in either the hard programming direction or the easy programming direction to set the RSE to a selected programmed state. A read circuit subsequently passes a read sense current through the cell in the hard programming direction to sense the selected programmed state of the cell.
    Type: Grant
    Filed: December 6, 2010
    Date of Patent: June 12, 2012
    Assignee: Seagate Technology LLC
    Inventors: Wenzhong Zhu, Hai Li, Yiran Chen, Xiaobin Wang, Henry Huang, Haiwen Xi
  • Patent number: 8197953
    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: Grant
    Filed: April 11, 2011
    Date of Patent: June 12, 2012
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Antoine Khoueir, Brian Lee, Pat Ryan, Michael Tang, Insik Jin, Paul E. Anderson
  • Patent number: 8199564
    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: June 15, 2011
    Date of Patent: June 12, 2012
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Haiwen Xi
  • Publication number: 20120127785
    Abstract: Method and apparatus for writing data to a magnetic memory cell, such as a spin-torque transfer random access memory (STRAM) memory cell. In accordance with various embodiments, a write current is applied through a selected magnetic memory cell to initiate magnetic precession of the selected cell to a desired magnetic state. A field assist current is concurrently flowed through an adjacent memory cell to generate a magnetic field that assists in the precession of the selected cell to the desired magnetic state.
    Type: Application
    Filed: November 19, 2010
    Publication date: May 24, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Andreas Karl Roelofs, Haiwen Xi
  • Publication number: 20120127786
    Abstract: An apparatus and associated method for a non-volatile memory cell, such as a multi-bit magnetic random access memory cell. In accordance with various embodiments, a first magnetic tunnel junction (MTJ) is adjacent to a second MTJ having a magnetic filter. The first MTJ is programmed to a first logical state with a first magnetic flux while the magnetic filter absorbs the first magnetic flux to prevent the second MTJ from being programmed.
    Type: Application
    Filed: November 23, 2010
    Publication date: May 24, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Nurul Amin, Dimitar V. Dimitrov, Haiwen Xi, Song S. Xue
  • Patent number: 8183654
    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: May 27, 2011
    Date of Patent: May 22, 2012
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Xiaohua Lou, Haiwen Xi, Michael Xuefei Tang
  • Publication number: 20120119313
    Abstract: An apparatus and associated method for a non-volatile memory cell with a phonon-blocking insulating layer. In accordance with various embodiments, a magnetic stack has a tunnel junction, ferromagnetic free layer, pinned layer, and an insulating layer that is constructed of an electrically and thermally insulative material that blocks phonons while allowing electrical transmission through at least one conductive feature.
    Type: Application
    Filed: November 16, 2010
    Publication date: May 17, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Xiaohua Lou, Wei Tian, Zheng Gao, Haiwen Xi
  • Publication number: 20120120708
    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: November 16, 2010
    Publication date: May 17, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Insik Jin, Xiaobin Wang, Yong Lu, Haiwen Xi
  • Patent number: 8179716
    Abstract: Spin torque magnetic logic device having at least one input element and an output element. Current is applied through the input element(s), and the resulting resistance or voltage across the output element is measured. The input element(s) include a free layer and the output element includes a free layer that is electrically connected to the free layer of the input element. The free layers of the input element and the output element may be electrically connected via magnetostatic coupling, or may be physically coupled. In some embodiments, the output element may have more than one free layer.
    Type: Grant
    Filed: November 24, 2010
    Date of Patent: May 15, 2012
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Yang Li, Song S. Xue
  • Publication number: 20120111952
    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: Application
    Filed: November 4, 2010
    Publication date: May 10, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Xin Cao, Haiwen Xi, Wenzhong Zhu, Robert Lamberton, Kaizhong Gao
  • Publication number: 20120104348
    Abstract: Methods for making a programmable metallization memory cell are disclosed.
    Type: Application
    Filed: January 11, 2012
    Publication date: May 3, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Ming Sun, Dexin Wang, Shuiyuan Huang, Michael Tang, Song S. Xue
  • Publication number: 20120106006
    Abstract: A magnetic read sensor having improved robustness to withstand thermal variations resulting from thermal fly height heating. Improved thermal robustness comes as a result of improved pinned layer pinning. The read head includes an AFM layer having an increased thickness to provide a higher blocking temperature. The read head further includes a pinned layer structure that includes a first magnetic layer adjacent to and exchange coupled with the AFM layer. The first layer comprises a Co—Fe layer with an increased Fe content of 20-30 atomic percent. The pinned layer structure also includes a second magnetic layer that is antiparallel coupled with the AP1 layer. The AP2 layer can be a multi-layer structure that includes a layer of CoFe, a layer of Co—Fe—Hf formed on the layer of Co—Fe, a layer of Co—Fe—B formed on the layer of Co—Fe—Hf, and a second layer of Co—Fe formed on the layer of Co—Fe—B.
    Type: Application
    Filed: October 28, 2010
    Publication date: May 3, 2012
    Applicant: Hitachi Global Storage Technologies Netherlands B. V.
    Inventors: Satoru Araki, Hardayal S. Gill, Hiroaki Chihaya, Dustin W. Erickson, Haiwen Xi, Chang Man Park
  • Publication number: 20120106239
    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: November 3, 2010
    Publication date: May 3, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Yuankai Zheng, Xiaobin Wang, Dimitar V. Dimitrov, Pat J. Ryan
  • Publication number: 20120087175
    Abstract: An apparatus and method for compensating for asymmetric write current in a non-volatile unit cell. The unit cell comprises a switching device and an asymmetric resistive sense element (RSE), such as an asymmetric resistive random access memory (RRAM) element or an asymmetric spin-torque transfer random access memory (STRAM) element. The RSE is physically oriented within the unit cell relative to the switching device such that a hard direction for programming the RSE is aligned with an easy direction of programming the unit cell, and an easy direction for programming the RSE is aligned with a hard direction for programming the unit cell.
    Type: Application
    Filed: December 21, 2011
    Publication date: April 12, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Wenzhong Zhu, Yong Lu, Xiaobin Wang, Yiran Chen, Alan Xuguang Wang, Xiaohua Lou, Haiwen Xi