Patents by Inventor Goran Mihajlovic

Goran Mihajlovic 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: 20210225421
    Abstract: A memory device includes a first electrode, a second electrode that is spaced from the first electrode, a fixed vertical magnetization structure configured to generate a fixed vertical magnetic field and located between the first electrode and the second electrode, at least one layer stack located between the fixed magnetization structure and the second electrode and containing respective spacer dielectric layer and a respective additional reference layer including a respective ferromagnetic material having perpendicular magnetic anisotropy, and a magnetic tunnel junction located between the at least one layer stack and the second electrode, the magnetic tunnel junction containing a reference layer, a free layer, and a nonmagnetic tunnel barrier layer located between the reference layer and the free layer, and the reference layer being more proximal to the at least one layer stack than the free layer is to the at least one layer stack.
    Type: Application
    Filed: March 16, 2021
    Publication date: July 22, 2021
    Inventors: Goran MIHAJLOVIC, Wonjoon JUNG, Bhagwati PRASAD
  • Patent number: 11004489
    Abstract: A perpendicular spin transfer torque MRAM memory cell includes a magnetic tunnel junction stack comprising a pinned layer having a fixed direction of magnetization, a free layer having a direction of magnetization that can be switched, a tunnel barrier between the pinned layer and the free layer, a cap layer above the free layer and one or more in-stack multi-layer thermal barrier layers having multiple internal interfaces between materials. The thermal barrier layers have high enough thermal resistivity to maintain the heat generated in the memory cell and low enough electrical resistivity to not materially change the electrical resistance of the memory cell. One embodiment further includes a thermal barrier liner surrounding the free layer, pinned layer, tunnel barrier and cap layer.
    Type: Grant
    Filed: July 1, 2019
    Date of Patent: May 11, 2021
    Assignee: Western Digital Technologies, Inc.
    Inventors: Goran Mihajlovic, Tiffany Santos, Michael Grobis
  • Patent number: 10957346
    Abstract: Disclosed herein are magnetic recording devices and methods of using them. A magnetic recording device comprises a main pole extending to an air-bearing surface (ABS), a trailing shield extending to the ABS, a write-field-enhancing structure disposed between and coupled to the main pole and the trailing shield at the ABS, a write coil configured to magnetize the main pole, a write current control circuit coupled to the write coil and configured to apply a write current to the write coil, wherein the write current comprises a write pulse, and a bias current control circuit coupled to the write-field-enhancing structure and configured to apply a bias current to the write-field-enhancing structure, wherein the bias current comprises a driving pulse offset in time from the write pulse by a delay, wherein the delay substantially coincides with an expected magnetization switch-time lag of a free layer of the write-field-enhancing structure.
    Type: Grant
    Filed: March 29, 2020
    Date of Patent: March 23, 2021
    Assignee: Western Digital Technologies, Inc.
    Inventors: Gonçalo Marcos Baião De Albuquerque, Yunfei Ding, Alexander Goncharov, Kuok San Ho, Daniele Mauri, Goran Mihajlovic, Suping Song, Petrus Antonius Van Der Heijden
  • Patent number: 10891999
    Abstract: A MRAM memory cell comprises a SHE layer, a magnetic bit layer with perpendicular anisotropy and an Oersted layer. The magnetic bit layer has a switchable direction of magnetization in order to store data. Data is written to the MRAM memory cell using the Spin Hall Effect so that spin current generated in the SHE layer exerts a torque on the magnetic bit layer while the Oersted layer provides heat and an Oersted field to enable deterministic switching. Data is read form the MRAM memory cell using the Anomalous Hall Effect and sensing voltage at the Oersted layer.
    Type: Grant
    Filed: July 1, 2019
    Date of Patent: January 12, 2021
    Assignee: Western Digital Technologies, Inc.
    Inventors: Goran Mihajlovic, Michael Grobis
  • Publication number: 20200402559
    Abstract: A perpendicular spin transfer torque MRAM memory cell includes a magnetic tunnel junction stack comprising a pinned layer having a fixed direction of magnetization, a free layer having a direction of magnetization that can be switched, a tunnel barrier between the pinned layer and the free layer, a cap layer above the free layer and one or more in-stack multi-layer thermal barrier layers having multiple internal interfaces between materials. The thermal barrier layers have high enough thermal resistivity to maintain the heat generated in the memory cell and low enough electrical resistivity to not materially change the electrical resistance of the memory cell. One embodiment further includes a thermal barrier liner surrounding the free layer, pinned layer, tunnel barrier and cap layer.
    Type: Application
    Filed: July 1, 2019
    Publication date: December 24, 2020
    Applicant: WESTERN DIGITAL TECHNOLOGIES, INC.
    Inventors: Goran Mihajlovic, Tiffany Santos, Michael Grobis
  • Publication number: 20200402561
    Abstract: A MRAM memory cell comprises a SHE layer, a magnetic bit layer with perpendicular anisotropy and an Oersted layer. The magnetic bit layer has a switchable direction of magnetization in order to store data. Data is written to the MRAM memory cell using the Spin Hall Effect so that spin current generated in the SHE layer exerts a torque on the magnetic bit layer while the Oersted layer provides heat and an Oersted field to enable deterministic switching. Data is read form the MRAM memory cell using the Anomalous Hall Effect and sensing voltage at the Oersted layer.
    Type: Application
    Filed: July 1, 2019
    Publication date: December 24, 2020
    Applicant: WESTERN DIGITAL TECHNOLOGIES, INC.
    Inventors: Goran Mihajlovic, Michael Grobis
  • Patent number: 10832750
    Abstract: A perpendicular spin transfer torque MRAM memory cell includes a magnetic tunnel junction that has a free layer, a pinned layer and a tunnel barrier between the free layer and the pinned layer. The free layer has a switchable direction of magnetization perpendicular to the plane of the free layer. A cap layer is provided adjacent to the magnetic tunnel junction. The thickness of the cap layer is increased so that the cap layer acts as a heating layer, which results in a reduction of the current density during writing and increases the write margin. In some embodiments, a resistive heating layer is added to the memory cell, adjacent to the cap layer, in order to achieve the lower current density and increased write margin while also improving signal to noise ration during reading by eliminating shot noise.
    Type: Grant
    Filed: February 22, 2019
    Date of Patent: November 10, 2020
    Assignee: SanDisk Technologies LLC
    Inventors: Goran Mihajlovic, Tiffany Santos, Jui-Lung Li
  • Publication number: 20200349967
    Abstract: Disclosed herein are magnetic recording devices and methods of using them. A magnetic recording device comprises a main pole extending to an air-bearing surface (ABS), a trailing shield extending to the ABS, a write-field-enhancing structure disposed between and coupled to the main pole and the trailing shield at the ABS, a write coil configured to magnetize the main pole, a write current control circuit coupled to the write coil and configured to apply a write current to the write coil, wherein the write current comprises a write pulse, and a bias current control circuit coupled to the write-field-enhancing structure and configured to apply a bias current to the write-field-enhancing structure, wherein the bias current comprises a driving pulse offset in time from the write pulse by a delay, wherein the delay substantially coincides with an expected magnetization switch-time lag of a free layer of the write-field-enhancing structure.
    Type: Application
    Filed: March 29, 2020
    Publication date: November 5, 2020
    Applicant: Western Digital Technologies, Inc.
    Inventors: Gonçalo Marcos Baião DE ALBUQUERQUE, Yunfei DING, Alexander GONCHAROV, Kuok San HO, Daniele MAURI, Goran MIHAJLOVIC, Suping SONG, Petrus Antonius VAN DER HEIJDEN
  • Patent number: 10777248
    Abstract: A magnetoresistive random access memory (MRAM) memory cell comprises a pinned layer having fixed direction of magnetization that is perpendicular to a plane of the pinned layer, a first free layer having a direction of magnetization that can be switched and is perpendicular to a plane of the first free layer, a tunnel barrier positioned between the pinned layer and the first free layer, a second free layer having a direction of magnetization that can be switched, and a spacer layer positioned between the first free layer and the second free layer. Temperature dependence of coercivity of the second free layer is greater than temperature dependence of coercivity of the first free layer.
    Type: Grant
    Filed: July 1, 2019
    Date of Patent: September 15, 2020
    Assignee: Western Digital Technologies, Inc.
    Inventors: Goran Mihajlovic, Neil Smith, Michael Grobis, Michael Tran
  • Publication number: 20200273510
    Abstract: A perpendicular spin transfer torque MRAM memory cell includes a magnetic tunnel junction that has a free layer, a pinned layer and a tunnel barrier between the free layer and the pinned layer. The free layer has a switchable direction of magnetization perpendicular to the plane of the free layer. A cap layer is provided adjacent to the magnetic tunnel junction. The thickness of the cap layer is increased so that the cap layer acts as a heating layer, which results in a reduction of the current density during writing and increases the write margin. In some embodiments, a resistive heating layer is added to the memory cell, adjacent to the cap layer, in order to achieve the lower current density and increased write margin while also improving signal to noise ration during reading by eliminating shot noise.
    Type: Application
    Filed: February 22, 2019
    Publication date: August 27, 2020
    Applicant: SANDISK TECHNOLOGIES LLC
    Inventors: Goran Mihajlovic, Tiffany Santos, Jui-Lung Li
  • Patent number: 10726893
    Abstract: A perpendicular spin orbit torque MRAM memory cell comprises a magnetic tunnel junction that includes a free layer in a plane, a ferromagnetic layer and a spacer layer between the ferromagnetic layer and the free layer. The free layer comprises a switchable direction of magnetization perpendicular to the plane. The ferromagnetic layer is configured to generate perpendicularly polarized spin current in response to an electrical current through the ferromagnetic layer and inject the perpendicularly polarized spin current through the spacer layer into the free layer to change the direction of magnetization of the free layer.
    Type: Grant
    Filed: December 12, 2018
    Date of Patent: July 28, 2020
    Assignee: SANDISK TECHNOLOGIES LLC
    Inventors: Goran Mihajlovic, Oleksandr Mosendz
  • Patent number: 10643642
    Abstract: An apparatus comprises a main pole, a trailing shield, a write-field-enhancing structure, a write coil, a write current control circuit configured to supply a write current to the write coil to record a bit to a magnetic medium, and a driving current control circuit configured to supply a driving current to the write-field-enhancing structure, wherein the driving current comprises a driving pulse, and wherein the driving current comprises an AC component with a duty cycle selected based at least in part on a power constraint. A method of writing to a magnetic medium comprises supplying a write current to a write coil of a magnetic write head, and supplying a driving current to a free layer disposed in a write gap between a main pole and a trailing shield, wherein the driving current comprises an AC component with a duty cycle based at least in part on a power constraint.
    Type: Grant
    Filed: July 1, 2019
    Date of Patent: May 5, 2020
    Assignee: Western Digital Technologies, Inc.
    Inventors: Gonçalo Marcos Baião De Albuquerque, Yunfei Ding, Alexander Goncharov, Kuok San Ho, Daniele Mauri, Goran Mihajlovic, Suping Song, Petrus Antonius Van Der Heijden
  • Publication number: 20200043538
    Abstract: A perpendicular spin orbit torque MRAM memory cell comprises a magnetic tunnel junction that includes a free layer in a plane, a ferromagnetic layer and a spacer layer between the ferromagnetic layer and the free layer. The free layer comprises a switchable direction of magnetization perpendicular to the plane. The ferromagnetic layer is configured to generate perpendicularly polarized spin current in response to an electrical current through the ferromagnetic layer and inject the perpendicularly polarized spin current through the spacer layer into the free layer to change the direction of magnetization of the free layer.
    Type: Application
    Filed: December 12, 2018
    Publication date: February 6, 2020
    Applicant: SANDISK TECHNOLOGIES LLC
    Inventors: Goran Mihajlovic, Oleksandr Mosendz
  • Publication number: 20190325902
    Abstract: An apparatus comprises a main pole, a trailing shield, a write-field-enhancing structure, a write coil, a write current control circuit configured to supply a write current to the write coil to record a bit to a magnetic medium, and a driving current control circuit configured to supply a driving current to the write-field-enhancing structure, wherein the driving current comprises a driving pulse, and wherein the driving current comprises an AC component with a duty cycle selected based at least in part on a power constraint. A method of writing to a magnetic medium comprises supplying a write current to a write coil of a magnetic write head, and supplying a driving current to a free layer disposed in a write gap between a main pole and a trailing shield, wherein the driving current comprises an AC component with a duty cycle based at least in part on a power constraint.
    Type: Application
    Filed: July 1, 2019
    Publication date: October 24, 2019
    Applicant: Western Digital Technologies, Inc.
    Inventors: Gonçalo Marcos Baião DE ALBUQUERQUE, Yunfei DING, Alexander GONCHAROV, Kuok San HO, Daniele MAURI, Goran MIHAJLOVIC, Suping SONG, Petrus Antonius VAN DER HEIJDEN
  • Patent number: 10388305
    Abstract: Disclosed herein are apparatuses and methods for writing to a magnetic medium, and data storage devices comprising such apparatuses and methods. An apparatus comprises a main pole, a trailing shield, a write-field-enhancing structure, a write coil, a write current control circuit configured to supply a write current to the write coil to record a bit to a magnetic medium, and a driving current control circuit configured to supply a driving current to the write-field-enhancing structure, wherein the driving current comprises a driving pulse. A method of writing to a magnetic medium comprises supplying a write current to a write coil of a magnetic write head, and supplying a driving current to a free layer disposed in a write gap between a main pole and a trailing shield of the magnetic write head, wherein the driving current comprises an AC component.
    Type: Grant
    Filed: March 12, 2018
    Date of Patent: August 20, 2019
    Assignee: Western Digital Technologies, Inc.
    Inventors: Gonçalo Marcos Baião De Albuquerque, Yunfei Ding, Alexander Goncharov, Kuok San Ho, Daniele Mauri, Goran Mihajlovic, Suping Song, Petrus Antonius Van Der Heijden
  • Patent number: 10381552
    Abstract: The present disclosure generally relates to a SOT-MRAM cell that has a spin Hall effect layer and a magnetic tunnel junction. The magnetic tunnel junction is disposed at an edge of the spin Hall effect layer. In order to write the cell, current is applied through the spin Hall effect layer to create spin accumulation of z-polarized spins under the free layer due to the spin Hall effect. The spins exert a spin torque on the free layer via spin diffusion. Based upon the design, the SOT-MRAM cell has deterministic switching of the perpendicular free layer with the spin Hall effect layer without application of an external magnetic field.
    Type: Grant
    Filed: June 17, 2016
    Date of Patent: August 13, 2019
    Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.
    Inventors: Goran Mihajlovic, Neil Smith
  • Patent number: 10290337
    Abstract: A method and apparatus for deterministically switching a free layer in a spin orbit torque magnetoresistive random access memory (SOT-MRAM) cell is disclosed herein. In one embodiment, an SOT-MRAM memory cell is provided. The SOT-MRAM memory cell includes a magnetic tunnel junction, a ferromagnetic bias layer, and an antiferromagnetic layer. The magnetic tunnel junction includes a free layer having primarily two bi-stable magnetization directions, a reference layer having a fixed magnetization direction, and an insulating tunnel barrier layer positioned between the free layer and the reference layer. The ferromagnetic bias layer is configured to provide spin orbit torque via anomalous Hall effect and simultaneously configured to provide a magnetic bias field on the free layer to achieve deterministic switching. The antiferromagnetic layer is positioned below the ferromagnetic bias layer and is configured to pin a magnetization direction of the ferromagnetic bias layer in a predetermined direction.
    Type: Grant
    Filed: November 27, 2017
    Date of Patent: May 14, 2019
    Assignee: WESTERN DIGITAL TECHNOLOGIES, INC.
    Inventors: Goran Mihajlovic, Neil Smith
  • Patent number: 10276783
    Abstract: A four terminal magnetoresistive memory cell comprises a magnetic tunnel junction stack, a ferroelectric layer and a non-ferromagnetic spin polarization layer between the magnetic tunnel junction stack and the ferroelectric layer. The magnetic tunnel junction includes a first layer with fixed direction of magnetization, a free layer capable of changing direction of magnetization and an insulation layer between the first layer and the free layer. The non-ferromagnetic spin polarization layer is configured to generate perpendicular spin polarization in response to electrical current through the non-ferromagnetic spin polarization layer and a voltage received at the ferroelectric layer. The perpendicular spin polarization applies a torque on the free layer to change direction of magnetization of the free layer.
    Type: Grant
    Filed: June 9, 2017
    Date of Patent: April 30, 2019
    Assignee: SanDisk Technologies LLC
    Inventors: Goran Mihajlovic, Jeffrey S. Lille
  • Patent number: 10211393
    Abstract: An MRAM memory cell is proposed that is based on spin accumulation torque. One embodiment includes a magnetic tunnel junction, a spin accumulation layer connected to the magnetic tunnel junction and a polarization layer connected to the spin accumulation layer. The polarization layer and the spin accumulation layer use spin accumulation to provide a spin accumulation torque on the free magnetic layer of the magnetic tunnel junction to change direction of magnetization of the free magnetic layer.
    Type: Grant
    Filed: February 23, 2017
    Date of Patent: February 19, 2019
    Assignee: SanDisk Technologies LLC
    Inventors: Goran Mihajlovic, Neil Smith, Jordan Asher Katine, Neil Leslie Robertson
  • Publication number: 20180358542
    Abstract: A four terminal magnetoresistive memory cell comprises a magnetic tunnel junction stack, a ferroelectric layer and a non-ferromagnetic spin polarization layer between the magnetic tunnel junction stack and the ferroelectric layer. The magnetic tunnel junction includes a first layer with fixed direction of magnetization, a free layer capable of changing direction of magnetization and an insulation layer between the first layer and the free layer. The non-ferromagnetic spin polarization layer is configured to generate perpendicular spin polarization in response to electrical current through the non-ferromagnetic spin polarization layer and a voltage received at the ferroelectric layer. The perpendicular spin polarization applies a torque on the free layer to change direction of magnetization of the free layer.
    Type: Application
    Filed: June 9, 2017
    Publication date: December 13, 2018
    Applicant: SANDISK TECHNOLOGIES LLC
    Inventors: Goran Mihajlovic, Jeffrey S. Lille