Patents by Inventor Dimitar V. Dimitrov

Dimitar V. Dimitrov 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: 7977722
    Abstract: Non-volatile memory with programmable capacitance is disclosed. Illustrative data memory units include a substrate including a source region and a drain region. A first insulating layer is over the substrate. A second insulating layer is over the substrate and between the source region and drain region. A solid electrolyte layer is between the first insulating layer and second insulating layer. The solid electrolyte layer has a capacitance that is controllable between at least two states. A first electrode is electrically coupled to a first side of the solid electrolyte layer and is electrically coupled to a voltage source. A second electrode is electrically coupled to a second side of the solid electrolyte layer and is electrically coupled to the voltage source. Multi-bit memory units are also disclosed.
    Type: Grant
    Filed: May 20, 2008
    Date of Patent: July 12, 2011
    Assignee: Seagate Technology LLC
    Inventors: Xuguang Wang, Shuiyuan Huang, Dimitar V. Dimitrov, Michael Xuefei Tang, Song S. Xue
  • Publication number: 20110164335
    Abstract: A magnetic sensor includes a reference layer having a first magnetization direction and a free layer assembly having an effective magnetization direction substantially perpendicular to the first magnetization direction and substantially perpendicular to a plane of each layer of the free layer assembly. A spacer layer is between the reference layer and the free layer, and a signal enhancement layer is exchange coupled to the free layer assembly on a side opposite the spacer layer.
    Type: Application
    Filed: March 15, 2011
    Publication date: July 7, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Song S. Xue, Zheng Gao, Shaoping Li, Kaizhong Gao, Dimitar V. Dimitrov, Konstantin Nikolaev, Patrick J. Ryan
  • Patent number: 7961509
    Abstract: A spin-transfer torque memory apparatus and self-reference read and write assist schemes are described. One method of self-reference reading a spin-transfer torque memory unit includes applying a first read current through a magnetic tunnel junction data cell and forming a first bit line read voltage. A magnetic field is applied through the free magnetic layer the forming a magnetic field modified magnetic tunnel junction data cell. Then a second read current is applied thorough the magnetic field modified magnetic tunnel junction data cell forming a second bit line read voltage and compared with the first bit line read voltage to determine whether the first resistance state of the magnetic tunnel junction data cell was a high resistance state or low resistance state. Methods of applying a destabilizing magnetic field to the MTJ and then writing the desired resistance state are also disclosed.
    Type: Grant
    Filed: October 13, 2010
    Date of Patent: June 14, 2011
    Assignee: Seagate Technology LLC
    Inventors: Wenzhong Zhu, Yiran Chen, Xiaobin Wang, Zheng Gao, Haiwen Xi, Dimitar V. Dimitrov
  • Publication number: 20110134682
    Abstract: Variable write and read methods for resistance random access memory (RRAM) are disclosed. The methods include initializing a write sequence and verifying the resistance state of the RRAM cell. If a write pulse is needed, then two or more write pulses are applied through the RRAM cell to write the desired data state to the RRAM cell. Each subsequent write pulse has substantially the same or greater write pulse duration. Subsequent write pulses are applied to the RRAM cell until the RRAM cell is in the desired data state or until a predetermined number of write pulses have been applied to the RRAM cell. A read method is also disclosed where subsequent read pulses are applied through the RRAM cell until the read is successful or until a predetermined number of read pulses have been applied to the RRAM cell.
    Type: Application
    Filed: February 16, 2011
    Publication date: June 9, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Hongyue Liu, Xiaobin Wang, Yong Lu, Yiran Chen, Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Hai Li
  • Publication number: 20110128778
    Abstract: A method and apparatus for using thermal preconditioning to write data to a non-volatile memory cell, such as a spin-torque transfer random access memory (STRAM) memory cell. In some embodiments, a logical state is written to an unconditioned non-volatile first memory cell associated with a first block address. Thermal preconditioning is concurrently applied to a non-volatile second memory cell associated with a second block address selected in response to the first block address.
    Type: Application
    Filed: January 28, 2011
    Publication date: June 2, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yiran Chen, Hai Li, Harry Hongyue Liu, Dimitar V. Dimitrov, Alan Xuguang Wang, Xiaobin Wang
  • Patent number: 7952917
    Abstract: Variable write and read methods for resistance random access memory (RRAM) are disclosed. The methods include initializing a write sequence and verifying the resistance state of the RRAM cell. If a write pulse is needed, then two or more write pulses are applied through the RRAM cell to write the desired data state to the RRAM cell. Each subsequent write pulse has substantially the same or greater write pulse duration. Subsequent write pulses are applied to the RRAM cell until the RRAM cell is in the desired data state or until a predetermined number of write pulses have been applied to the RRAM cell. A read method is also disclosed where subsequent read pulses are applied through the RRAM cell until the read is successful or until a predetermined number of read pulses have been applied to the RRAM cell.
    Type: Grant
    Filed: June 4, 2010
    Date of Patent: May 31, 2011
    Assignee: Seagate Technology LLC
    Inventors: Haiwen Xi, Hongyue Liu, Xiaobin Wang, Yong Lu, Yiran Chen, Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Hai Li
  • Publication number: 20110121418
    Abstract: A free ferromagnetic data storage layer of an MRAM cell is coupled to a free ferromagnetic stabilization layer, which stabilization layer is directly electrically coupled to a contact electrode, on one side, and is separated from the free ferromagnetic data storage layer, on an opposite side, by a spacer layer. The spacer layer provides for the coupling between the two free layers, which coupling is one of: a ferromagnetic coupling and an antiferromagnetic coupling.
    Type: Application
    Filed: January 27, 2011
    Publication date: May 26, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Haiwen Xi, Kaizhong Gao, Dimitar V. Dimitrov, Song S. Xue
  • Patent number: 7944742
    Abstract: A memory array includes a cross-point array of bit and source lines. A memory is disposed at cross-points of the cross-point array. The memory unit includes a magnetic tunnel junction data cell electrically coupled to a bit line and a source line. The magnetic tunnel junction data cell is configured to switch between a high resistance state and a low resistance state by passing a polarized write current through the magnetic tunnel junction data cell. A transistor is electrically between the magnetic tunnel junction data cell and the bit line or source line and a diode is in thermal or electrical contact with the magnetic tunnel junction data cell to assist in resistance state switching.
    Type: Grant
    Filed: August 24, 2010
    Date of Patent: May 17, 2011
    Assignee: Seagate Technology LLC
    Inventors: Xuguang Wang, Yiran Chen, Dimitar V. Dimitrov, Hongyue Liu, Xiaobin Wang
  • Patent number: 7940551
    Abstract: Spin-transfer torque memory having a specular insulative spacer is disclosed. The spin-transfer torque memory unit includes a free magnetic layer, a reference magnetic layer, an electrically insulating and non-magnetic tunneling barrier layer separating the free magnetic layer from the reference magnetic layer, an electrode layer, and an electrically insulating and electronically reflective layer separating the electrode layer and the free magnetic layer.
    Type: Grant
    Filed: September 29, 2008
    Date of Patent: May 10, 2011
    Assignee: Seagate Technology, LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Wei Tian, Dexin Wang, Zheng Gao, Xiaobin Wang
  • Patent number: 7940592
    Abstract: Method and apparatus for using a uni-directional write current to store different logic states in a non-volatile memory cell, such as a modified STRAM cell. In some embodiments, the memory cell has an unpinned ferromagnetic reference layer adjacent a cladded conductor, a ferromagnetic storage layer and a tunneling barrier between the reference layer and the storage layer. Passage of a current along the cladded conductor induces a selected magnetic orientation in the reference layer, which is transferred through the tunneling barrier for storage by the storage layer. Further, the orientation of the applying step is provided by a cladding layer adjacent a conductor along which a current is passed and the current induces a magnetic field in the cladding layer of the selected magnetic orientation.
    Type: Grant
    Filed: December 2, 2008
    Date of Patent: May 10, 2011
    Assignee: Seagate Technology LLC
    Inventors: Daniel Seymour Reed, Yon Lu, Song S. Xue, Dimitar V. Dimitrov, Paul E. Anderson
  • Patent number: 7933137
    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: Grant
    Filed: March 31, 2009
    Date of Patent: April 26, 2011
    Assignee: Seagate Teachnology LLC
    Inventors: Dimitar V. Dimitrov, Olle Gunnar Heinonen, Yiran Chen, Haiwen Xi, Xiaohua Lou
  • Patent number: 7933146
    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: Grant
    Filed: March 31, 2009
    Date of Patent: April 26, 2011
    Assignee: Seagate Technology LLC
    Inventors: Dimitar V. Dimitrov, Olle Gunnar Heinonen, Yiran Chen, Haiwen Xi, Xiaohua Lou
  • Publication number: 20110089509
    Abstract: Magnetic memory having separate read and write paths is disclosed. The magnetic memory unit includes a ferromagnetic strip having a first end portion with a first magnetization orientation, an opposing second end portion with a second magnetization orientation, and a middle portion between the first end portion and the second end portion, the middle portion having a free magnetization orientation. The first magnetization orientation opposes the second magnetization orientation. A tunneling barrier separates a magnetic reference layer from the middle portion forming a magnetic tunnel junction. A bit line is electrically coupled to the second end portion. A source line is electrically coupled to the first end portion and a read line is electrically coupled to the magnetic tunnel junction.
    Type: Application
    Filed: December 21, 2010
    Publication date: April 21, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yong Lu, Hongyue Liu, Zheng Gao, Insik Jin, Dimitar V. Dimitrov
  • Patent number: 7929258
    Abstract: A magnetic sensor includes a reference layer having a first magnetization direction and a free layer assembly having an effective magnetization direction substantially perpendicular to the first magnetization direction and substantially perpendicular to a plane of each layer of the free layer assembly. A spacer layer is between the reference layer and the free layer, and a signal enhancement layer is exchange coupled to the free layer assembly on a side opposite the spacer layer.
    Type: Grant
    Filed: January 22, 2008
    Date of Patent: April 19, 2011
    Assignee: Seagate Technology LLC
    Inventors: Song S. Xue, Zheng Gao, Shaoping Li, Kaizhong Gao, Dimitar V. Dimitrov, Konstantin Nikolaev, Patrick J. Ryan
  • Publication number: 20110085373
    Abstract: Self-reference reading a magnetic tunnel junction data cell methods are disclosed. An illustrative method includes applying a read voltage across a magnetic tunnel junction data cell and forming a read current. The magnetic tunnel junction data cell has a first resistance state. The read voltage is sufficient to switch the magnetic tunnel junction data cell resistance. The method includes detecting the read current and determining if the read current remains constant during the applying step. If the read current remains constant during the applying step, then the first resistance state of the magnetic tunnel junction data cell is the resistance state that the read voltage was sufficient to switch the magnetic tunnel junction data cell to.
    Type: Application
    Filed: December 15, 2010
    Publication date: April 14, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Yiran Chen, Xiaobin Wang, Zheng Gao, Dimitar V. Dimitrov, Wenzhong Zhu, Yong Lu
  • Patent number: 7916528
    Abstract: A method and apparatus for using thermal preconditioning to write data to a non-volatile memory cell, such as a spin-torque transfer random access memory (STRAM) memory cell. In some embodiments, a logical state is written to an unconditioned non-volatile first memory cell associated with a first block address. Thermal preconditioning is concurrently applied to a non-volatile second memory cell associated with a second block address selected in response to the first block address.
    Type: Grant
    Filed: March 30, 2009
    Date of Patent: March 29, 2011
    Assignee: Seagate Technology LLC
    Inventors: Yiran Chen, Hai Li, Harry Hongyue Liu, Dimitar V. Dimitrov, Alan Xuguang Wang, Xiaobin Wang
  • Publication number: 20110049658
    Abstract: Magnetic tunnel junctions having a specular insulative spacer are disclosed. The magnetic tunnel junction includes a free magnetic layer, a reference magnetic layer, an electrically insulating and non-magnetic tunneling barrier layer separating the free magnetic layer from the reference magnetic layer, and an electrically insulating and electronically reflective layer positioned to reflect at least a portion of electrons back into the free magnetic layer.
    Type: Application
    Filed: November 11, 2010
    Publication date: March 3, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Wei Tian, Dexin Wang, Zheng Gao, Xiaobin Wang
  • Patent number: 7894250
    Abstract: A method and apparatus for repairing a stuck-at defect condition in a non-volatile memory cell, such as a spin-torque transfer random access memory (STRAM). In some embodiments, a resistive sense element has a magnetic tunneling junction (MTJ) and a repair plane located adjacent to the resistive sense element. The repair plane injects a magnetic field in the MTJ to repair a stuck-at defect condition.
    Type: Grant
    Filed: March 17, 2009
    Date of Patent: February 22, 2011
    Assignee: Seagate Technology LLC
    Inventors: Alan Xuguang Wang, Xiaobin Wang, Dimitar V. Dimitrov, Hai Li, Haiwen Xi, Harry Hongyue Liu
  • Publication number: 20110026321
    Abstract: A magnetic element having a ferromagnetic pinned layer, a ferromagnetic free layer, a non-magnetic spacer layer therebetween, and a porous non-electrically conducting current confinement layer between the free layer and the pinned layer. The current confinement layer forms an interface either between the free layer and the non-magnetic spacer layer or the pinned layer and the non-magnetic spacer layer.
    Type: Application
    Filed: October 14, 2010
    Publication date: February 3, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Michael Xuefei Tang, Ming Sun, Dimitar V. Dimitrov, Patrick Ryan
  • Publication number: 20110026317
    Abstract: A spin-transfer torque memory apparatus and self-reference read and write assist schemes are described. One method of self-reference reading a spin-transfer torque memory unit includes applying a first read current through a magnetic tunnel junction data cell and forming a first bit line read voltage. A magnetic field is applied through the free magnetic layer the forming a magnetic field modified magnetic tunnel junction data cell. Then a second read current is applied thorough the magnetic field modified magnetic tunnel junction data cell forming a second bit line read voltage and compared with the first bit line read voltage to determine whether the first resistance state of the magnetic tunnel junction data cell was a high resistance state or low resistance state. Methods of applying a destabilizing magnetic field to the MTJ and then writing the desired resistance state are also disclosed.
    Type: Application
    Filed: October 13, 2010
    Publication date: February 3, 2011
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Wenzhong Zhu, Yiran Chen, Xiaobin Wang, Zheng Gao, Haiwen Xi, Dimitar V. Dimitrov