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).

  • Publication number: 20120250405
    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: Application
    Filed: June 8, 2012
    Publication date: October 4, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Xiaobin Wang, Haiwen Xi, Hongyue Liu, Insik Jin, Andreas Roelofs, Eileen Yan, Dimitar V. Dimitrov
  • Patent number: 8279662
    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 magnetic tunnel junction (MTJ) has a ferromagnetic free layer with multiple magnetic domains that are each independently programmable to predetermined magnetizations. Those magnetizations can then be read as different logical states of the MTJ.
    Type: Grant
    Filed: November 11, 2010
    Date of Patent: October 2, 2012
    Assignee: Seagate Technology LLC
    Inventors: Xiaohua Lou, Zheng Gao, Dimitar V. Dimitrov
  • Publication number: 20120229935
    Abstract: An apparatus and associated method is presently disclosed for a data sensing element capable of detecting changes in magnetic states. Various embodiments of the present invention are generally directed to a magnetically responsive lamination that has a spacer layer disposed between a first and second ferromagnetic free layer. The lamination having at least one free layer with a shape feature that increases a scissoring angle between the free layers.
    Type: Application
    Filed: March 8, 2011
    Publication date: September 13, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Dian Song, Dimitar V. Dimitrov, Mark W. Covington, Jiexuan He, Scott Stokes, Jason Gadbois
  • Publication number: 20120230092
    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: May 18, 2012
    Publication date: September 13, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Haiwen Xi
  • Publication number: 20120224417
    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: Application
    Filed: May 16, 2012
    Publication date: September 6, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Xuguang Wang, Yiran Chen, Dimitar V. Dimitrov, Hongyue Liu, Xiaobin Wang
  • Publication number: 20120201075
    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: Application
    Filed: April 13, 2012
    Publication date: August 9, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Wenzhong Zhu, Xiaohua Lou, Dimitar V. Dimitrov
  • 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
  • Patent number: 8213222
    Abstract: A magnetic tunnel junction having a compsensation element is disclosed. The magnetic tunnel junction includes a reference element, and a compensation element having an opposite magnetization moment to a magnetization moment of the reference element. A free magnetic layer is between the reference element and the compensation element, and an electrically insulating and non-magnetic tunneling barrier layer separates the free magnetic layer from the reference element. The free magnetic layer includes Co100-X-YFeXBY wherein X is a value being greater than 30 and Y is a value being greater than 15.
    Type: Grant
    Filed: August 16, 2011
    Date of Patent: July 3, 2012
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Dimitar V. Dimitrov, Dexin Wang, Wei Tian, Xiaobin Wang, Xiaohua Lou
  • Patent number: 8203871
    Abstract: Spin torque magnetic logic devices that function as memory devices and that can be reconfigured or reprogrammed as desired. In some embodiments, the logic device is a single magnetic element, having a pinned layer, a free layer, and a barrier layer therebetween, or in other embodiments, the logic device has two magnetic elements in series. Two input currents can be applied through the element to configure or program the element. In use, logic input data, such as current, is passed through the programmed element, defining the resistance across the element and the resulting logic output. The magnetic logic device can be used for an all-function-in-one magnetic chip.
    Type: Grant
    Filed: November 30, 2010
    Date of Patent: June 19, 2012
    Assignee: Seagate Technology LLC
    Inventors: Xiaohua Lou, Dimitar V. Dimitrov, Song S. Xue
  • 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
  • Publication number: 20120147665
    Abstract: Method and apparatus for using thermal preconditioning to write data to a non-volatile memory cell. In accordance with some embodiments, a semiconductor memory has an array of non-volatile memory cells, and a control circuit which stores a first write command from a host to write data to said array. A write circuit flows a write current through an unconditioned first selected cell having a first block address associated with the first write command to write the first selected cell to a selected data state, and concurrently passes a thermal preconditioning current through a second selected cell having a second block address associated with the first block address. The write circuit further passes a thermal preconditioning current through a third selected cell having a third block address associated with the second block address in response to receipt by the control circuit of a second write command from the host associated with the second block address.
    Type: Application
    Filed: February 20, 2012
    Publication date: June 14, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Yiran Chen, Hai Li, Harry Hongyue Liu, Dimitar V. Dimitrov, Alan Xuguang Wang, Xiaobin Wang
  • Patent number: 8198660
    Abstract: A multi-bit spin torque magnetic element that has a ferromagnetic pinned layer having a pinned magnetization orientation, a non-magnetic layer, and a ferromagnetic free layer having a magnetization orientation switchable among at least four directions, the at least four directions being defined by a physical shape of the free layer. The magnetic element has at least four distinct resistance states. Magnetic elements with at least eight magnetization directions are also provided.
    Type: Grant
    Filed: August 27, 2010
    Date of Patent: June 12, 2012
    Assignee: Seagate Technology LLC
    Inventors: Dimitar V. Dimitrov, Zheng Gao, Xiaobin Wang
  • 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
  • Patent number: 8199569
    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: April 15, 2011
    Date of Patent: June 12, 2012
    Assignee: Seagate Technology LLC
    Inventors: Xuguang Wang, Yiran Chen, Dimitar V. Dimitrov, Hongyue Liu, Xiaobin Wang
  • Publication number: 20120138884
    Abstract: Programmable metallization memory cells having a planarized silver electrode and methods of forming the same are disclosed. The programmable metallization memory cells include a first metal contact and a second metal contact, an ion conductor solid electrolyte material is between the first metal contact and the second metal contact, and either a silver alloy doping electrode separates the ion conductor solid electrolyte material from the first metal contact or the second metal contact, or a silver doping electrode separates the ion conductor solid electrolyte material from the first metal contact. The silver electrode includes a silver layer and a metal seed layer separating the silver layer from the first metal contact.
    Type: Application
    Filed: February 15, 2012
    Publication date: June 7, 2012
    Applicant: SEAGATE TECHNOLOGY LLC.
    Inventors: Wei Tian, Dexin Wang, Venugopalan Vaithyanathan, Yang Dong, Muralikrishnan Balakrishnan, Ivan Petrov Ivanov, Ming Sun, Dimitar V. Dimitrov
  • Publication number: 20120142169
    Abstract: Programmable metallization memory cells having a planarized silver electrode and methods of forming the same are disclosed. The programmable metallization memory cells include a first metal contact and a second metal contact, an ion conductor solid electrolyte material is between the first metal contact and the second metal contact, and either a silver alloy doping electrode separates the ion conductor solid electrolyte material from the first metal contact or the second metal contact, or a silver doping electrode separates the ion conductor solid electrolyte material from the first metal contact. The silver electrode includes a silver layer and a metal seed layer separating the silver layer from the first metal contact.
    Type: Application
    Filed: February 8, 2012
    Publication date: June 7, 2012
    Applicant: SEAGATE TECHNOLOGY LLC
    Inventors: Wei Tian, Dexin Wang, Venugopalan Vaithyanathan, Yang Dong, Muralikrishnan Balakrishnan, Ivan Petrov Ivanov, Ming Sun, Dimitar V. Dimitrov
  • Patent number: 8194444
    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: Grant
    Filed: December 15, 2010
    Date of Patent: June 5, 2012
    Assignee: Seagate Technology LLC
    Inventors: Yuankai Zheng, Yiran Chen, Xiaobin Wang, Zheng Gao, Dimitar V. Dimitrov, Wenzhong Zhu, Yong Lu
  • Patent number: 8188558
    Abstract: In order to increase an efficiency of spin transfer and thereby reduce the required switching current, a current perpendicular to plane (CPP) magnetic element for a memory device includes either one or both of a free magnetic layer, which has an electronically reflective surface, and a permanent magnet layer, which has perpendicular anisotropy to bias the free magnetic layer.
    Type: Grant
    Filed: June 27, 2011
    Date of Patent: May 29, 2012
    Assignee: Seagate Technology LLC
    Inventors: Dexin Wang, Dimitar V. Dimitrov, Song S. Xue, Insik Jin
  • 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