Patents by Inventor Robert A. Buhrman

Robert A. Buhrman 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: 20210280775
    Abstract: Methods, systems, and devices are disclosed for enhancement of spin-orbit torque. In one aspect, a magnetic device includes a magnetic tunneling junction (MTJ), including a free magnetic layer, a pinned magnetic layer and a non-magnetic junction layer between the free magnetic layer and the pinned magnetic layer, and a spin Hall effect metal layer that includes one or more insertion metal layers operable to introduce interfacial scattering of electrons flowing in the spin Hall metal layer to increase the spin current that interacts with and changes the magnetization of the free magnetic layer of the MTJ.
    Type: Application
    Filed: March 16, 2020
    Publication date: September 9, 2021
    Inventors: Robert A. BUHRMAN, Lijun ZHU
  • Patent number: 10847197
    Abstract: Devices or circuits based on spin torque transfer (STT) and Spin Hall effect are disclosed by using a spin Hall effect (SHE) metal layer coupled to a magnetic free layer for various applications. The efficiency or strength of the STT effect based on this combination of SHE and STT can be enhanced by an interface modification between the SHE metal layer and the magnetic free layer or by modifying or engineering the SHE metal layer by doping the SHE metal with certain impurities or other means.
    Type: Grant
    Filed: June 25, 2018
    Date of Patent: November 24, 2020
    Assignee: Cornell University
    Inventors: Robert A. Buhrman, Minh-hai Nguyen, Chi-feng Pai, Daniel C. Ralph
  • Patent number: 10333058
    Abstract: The disclosed technology provides various implementations of a device based on a spin Hall effect (SHE) and spin transfer torque (STT) effect.
    Type: Grant
    Filed: March 17, 2017
    Date of Patent: June 25, 2019
    Assignee: Cornell University
    Inventors: Sriharsha V. Aradhya, Robert A. Buhrman, Daniel C. Ralph, Graham E. Rowlands
  • Publication number: 20180308536
    Abstract: Devices or circuits based on spin torque transfer (STT) and Spin Hall effect are disclosed by using a spin Hall effect (SHE) metal layer coupled to a magnetic free layer for various applications. The efficiency or strength of the STT effect based on this combination of SHE and STT can be enhanced by an interface modification between the SHE metal layer and the magnetic free layer or by modifying or engineering the SHE metal layer by doping the SHE metal with certain impurities or other means.
    Type: Application
    Filed: June 25, 2018
    Publication date: October 25, 2018
    Inventors: Robert A. Buhrman, Minh-hai Nguyen, Chi-feng Pai, Daniel C. Ralph
  • Publication number: 20180301266
    Abstract: A device implemented based on the disclosed technology includes a thin-film magnetic structure that includes a substrate and thin film layers formed over the substrate to include a ferromagnetic layer formed over the substrate, and a non-magnetic dusting layer in contact with the ferromagnetic layer and structured to have a thickness around one molecular layer to enhance an interfacial perpendicular magnetic anisotropy energy density of the ferromagnetic layer.
    Type: Application
    Filed: April 17, 2018
    Publication date: October 18, 2018
    Inventors: Yongxi Ou, Robert A. Buhrman, Daniel C. Ralph
  • Patent number: 10008248
    Abstract: Devices or circuits based on spin torque transfer (STT) and Spin Hall effect are disclosed by using a spin Hall effect (SHE) metal layer coupled to a magnetic free layer for various applications. The efficiency or strength of the STT effect based on this combination of SHE and STT can be enhanced by an interface modification between the SHE metal layer and the magnetic free layer or by modifying or engineering the SHE metal layer by doping the SHE metal with certain impurities or other means.
    Type: Grant
    Filed: July 17, 2015
    Date of Patent: June 26, 2018
    Assignee: Cornell University
    Inventors: Robert A Buhrman, Minh-hai Nguyen, Chi-feng Pai, Daniel C Ralph
  • Patent number: 9947382
    Abstract: Three-terminal magnetic circuits and devices based on the spin-transfer torque (STT) effect via a combination of injection of spin-polarized electrons or charged particles by using a charge current in a spin Hall effect metal layer coupled to a free magnetic layer and application of a gate voltage to the free magnetic layer to manipulate the magnetization of the free magnetic layer for various applications, including nonvolatile memory functions, logic functions and others. The charge current is applied to the spin Hall effect metal layer via first and second electrical terminals and the gate voltage is applied between a third electrical terminal and either of the first and second electrical terminals. The spin Hall effect metal layer can be adjacent to the free magnetic layer or in direct contact with the free magnetic layer to allow a spin-polarized current generated via a spin Hall effect under the charge current to enter the free magnetic layer.
    Type: Grant
    Filed: November 21, 2016
    Date of Patent: April 17, 2018
    Assignee: Cornell University
    Inventors: Robert A Buhrman, Daniel C Ralph, Chi-Feng Pai, Luqiao Liu
  • Publication number: 20180033954
    Abstract: The disclosed technology provides various implementations of a device based on a spin Hall effect (SHE) and spin transfer torque (STT) effect.
    Type: Application
    Filed: March 17, 2017
    Publication date: February 1, 2018
    Inventors: Sriharsha V. Aradhya, Robert A. Buhrman, Daniel C. Ralph, Graham E. Rowlands
  • Patent number: 9691458
    Abstract: A device based on a spin Hall effect and spin-transfer torque (STT) effect is provided to include a magnetic tunneling junction (MTJ) element including a free magnetic layer structured to have a magnetization direction that can be changed by spin-transfer torque; an electrically conducting magnetic layer structure exhibiting a spin Hall effect (SHE) and, in response to an applied in-plane charge current, generating a spin-polarized current of a magnetic moment oriented in a predetermined direction having both an in-plane magnetic moment component parallel to a surface of the electrically conducting magnetic layer structure and a perpendicular magnetic moment component perpendicular to the surface of the electrically conducting magnetic layer structure. The magnetization direction of the free magnetic layer is capable of being switched by the spin-polarized current via a spin-transfer torque (STT) effect. This device can be configured in a 3-terminal configuration.
    Type: Grant
    Filed: October 20, 2014
    Date of Patent: June 27, 2017
    Assignee: Cornell University
    Inventors: Daniel C. Ralph, Robert A. Buhrman
  • Publication number: 20170178705
    Abstract: Devices or circuits based on spin torque transfer (STT) and Spin Hall effect are disclosed by using a spin Hall effect (SHE) metal layer coupled to a magnetic free layer for various applications. The efficiency or strength of the STT effect based on this combination of SHE and STT can be enhanced by an interface modification between the SHE metal layer and the magnetic free layer or by modifying or engineering the SHE metal layer by doping the SHE metal with certain impurities or other means.
    Type: Application
    Filed: July 17, 2015
    Publication date: June 22, 2017
    Inventors: Robert A Buhrman, Minh-hai Nguyen, Chi-feng Pai, Daniel C Ralph
  • Publication number: 20170069365
    Abstract: 3-terminal magnetic circuits and devices based on the spin-transfer torque (STT) effect via a combination of injection of spin-polarized electrons or charged particles by using a charge current in a spin Hall effect metal layer coupled to a free magnetic layer and application of a gate voltage to the free magnetic layer to manipulate the magnetization of the free magnetic layer for various applications, including non-volatile memory functions, logic functions and others. The charge current is applied to the spin Hall effect metal layer via first and second electrical terminals and the gate voltage is applied between a third electrical terminal and either of the first and second electrical terminals. The spin Hall effect metal layer can be adjacent to the free magnetic layer or in direct contact with the free magnetic layer to allow a spin-polarized current generated via a spin Hall effect under the charge current to enter the free magnetic layer.
    Type: Application
    Filed: November 21, 2016
    Publication date: March 9, 2017
    Inventors: Robert A Buhrman, Daniel C Ralph, Chi-Feng Pai, Luqiao Liu
  • Patent number: 9577653
    Abstract: Techniques, systems, and devices are disclosed for implementing a quasi-linear spin-torque nano-oscillator based on exertion of a spin-transfer torque on the local magnetic moments in the magnetic layer and precession of the magnetic moments in the magnetic layer within a spin valve. Examples of spin-torque nano-oscillators (STNOs) are disclosed to use spin polarized currents to excite nano magnets that undergo persistent oscillations at RF or microwave frequencies. The spin currents are applied in a non-uniform manner to both excite the nano magnets into oscillations and generate dynamic damping at large amplitude as a feedback to reduce the nonlinearity associated with mixing amplitude and phase fluctuations.
    Type: Grant
    Filed: January 14, 2014
    Date of Patent: February 21, 2017
    Assignee: CORNELL UNIVERSITY
    Inventors: Robert A. Buhrman, Oukjae Lee, Daniel C. Ralph
  • Patent number: 9576631
    Abstract: An ST-MRAM structure, a method for fabricating the ST-MRAM structure and a method for operating an ST-MRAM device that results from the ST-MRAM structure each utilize a spin Hall effect base layer that contacts a magnetic free layer and effects a magnetic moment switching within the magnetic free layer as a result of a lateral switching current within the spin Hall effect base layer. This resulting ST-MRAM device uses an independent sense current and sense voltage through a magnetoresistive stack that includes a pinned layer, a non-magnetic spacer layer and the magnetic free layer which contacts the spin Hall effect base layer. Desirable non-magnetic conductor materials for the spin Hall effect base layer include certain types of tantalum materials and tungsten materials that have a spin diffusion length no greater than about five times the thickness of the spin Hall effect base layer and a spin Hall angle at least about 0.05.
    Type: Grant
    Filed: August 10, 2015
    Date of Patent: February 21, 2017
    Assignee: Cornell University
    Inventors: Robert A. Buhrman, Luqiao Liu, Daniel C. Ralph, Chi-Feng Pai
  • Patent number: 9502087
    Abstract: 3-terminal magnetic circuits and devices based on the spin-transfer torque (STT) effect via a combination of injection of spin-polarized electrons or charged particles by using a charge current in a spin Hall effect metal layer coupled to a free magnetic layer and application of a gate voltage to the free magnetic layer to manipulate the magnetization of the free magnetic layer for various applications, including non-volatile memory functions, logic functions and others. The charge current is applied to the spin Hall effect metal layer via first and second electrical terminals and the gate voltage is applied between a third electrical terminal and either of the first and second electrical terminals. The spin Hall effect metal layer can be adjacent to the free magnetic layer or in direct contact with the free magnetic layer to allow a spin-polarized current generated via a spin Hall effect under the charge current to enter the free magnetic layer.
    Type: Grant
    Filed: December 31, 2015
    Date of Patent: November 22, 2016
    Assignee: CORNELL UNIVERSITY
    Inventors: Robert A. Buhrman, Daniel C. Ralph, Chi-Feng Pai, Luqiao Liu
  • Publication number: 20160276006
    Abstract: A device based on a spin Hall effect and spin-transfer torque (STT) effect is provided to include a magnetic tunneling junction (MTJ) element including a free magnetic layer structured to have a magnetization direction that can be changed by spin-transfer torque; an electrically conducting magnetic layer structure exhibiting a spin Hall effect (SHE) and, in response to an applied in-plane charge current, generating a spin-polarized current of a magnetic moment oriented in a predetermined direction having both an in-plane magnetic moment component parallel to a surface of the electrically conducting magnetic layer structure and a perpendicular magnetic moment component perpendicular to the surface of the electrically conducting magnetic layer structure. The magnetization direction of the free magnetic layer is capable of being switched by the spin-polarized current via a spin-transfer torque (STT) effect. This device can be configured in a 3-terminal configuration.
    Type: Application
    Filed: October 20, 2014
    Publication date: September 22, 2016
    Applicant: CORNELL UNIVERSITY
    Inventors: Daniel C. Ralph, Robert A. Buhrman
  • Publication number: 20160196860
    Abstract: 3-terminal magnetic circuits and devices based on the spin-transfer torque (STT) effect via a combination of injection of spin-polarized electrons or charged particles by using a charge current in a spin Hall effect metal layer coupled to a free magnetic layer and application of a gate voltage to the free magnetic layer to manipulate the magnetization of the free magnetic layer for various applications, including non-volatile memory functions, logic functions and others. The charge current is applied to the spin Hall effect metal layer via first and second electrical terminals and the gate voltage is applied between a third electrical terminal and either of the first and second electrical terminals. The spin Hall effect metal layer can be adjacent to the free magnetic layer or in direct contact with the free magnetic layer to allow a spin-polarized current generated via a spin Hall effect under the charge current to enter the free magnetic layer.
    Type: Application
    Filed: December 31, 2015
    Publication date: July 7, 2016
    Inventors: Robert A. Buhrman, Daniel C. Ralph, Chi-Feng Pai, Luqiao Liu
  • Patent number: 9230626
    Abstract: 3-terminal magnetic circuits and devices based on the spin-transfer torque (STT) effect via a combination of injection of spin-polarized electrons or charged particles by using a charge current in a spin Hall effect metal layer coupled to a free magnetic layer and application of a gate voltage to the free magnetic layer to manipulate the magnetization of the free magnetic layer for various applications, including non-volatile memory functions, logic functions and others. The charge current is applied to the spin Hall effect metal layer via first and second electrical terminals and the gate voltage is applied between a third electrical terminal and either of the first and second electrical terminals. The spin Hall effect metal layer can be adjacent to the free magnetic layer or in direct contact with the free magnetic layer to allow a spin-polarized current generated via a spin Hall effect under the charge current to enter the free magnetic layer.
    Type: Grant
    Filed: August 6, 2013
    Date of Patent: January 5, 2016
    Assignee: CORNELL UNIVERSITY
    Inventors: Robert A. Buhrman, Daniel C. Ralph, Chi-Feng Pai, Luqiao Liu
  • Publication number: 20150372687
    Abstract: Techniques, systems, and devices are disclosed for implementing a quasi-linear spin-torque nano-oscillator based on exertion of a spin-transfer torque on the local magnetic moments in the magnetic layer and precession of the magnetic moments in the magnetic layer within a spin valve. Examples of spin-torque nano-oscillators (STNOs) are disclosed to use spin polarized currents to excite nano magnets that undergo persistent oscillations at RF or microwave frequencies. The spin currents are applied in a non-uniform manner to both excite the nano magnets into oscillations and generate dynamic damping at large amplitude as a feedback to reduce the nonlinearity associated with mixing amplitude and phase fluctuations.
    Type: Application
    Filed: January 14, 2014
    Publication date: December 24, 2015
    Applicant: Cornell University
    Inventors: Robert A. Buhrman, Oukjae Lee, Daniel C. Ralph
  • Publication number: 20150348606
    Abstract: An ST-MRAM structure, a method for fabricating the ST-MRAM structure and a method for operating an ST-MRAM device that results from the ST-MRAM structure each utilize a spin Hall effect base layer that contacts a magnetic free layer and effects a magnetic moment switching within the magnetic free layer as a result of a lateral switching current within the spin Hall effect base layer. This resulting ST-MRAM device uses an independent sense current and sense voltage through a magnetoresistive stack that includes a pinned layer, a non-magnetic spacer layer and the magnetic free layer which contacts the spin Hall effect base layer. Desirable non-magnetic conductor materials for the spin Hall effect base layer include certain types of tantalum materials and tungsten materials that have a spin diffusion length no greater than about five times the thickness of the spin Hall effect base layer and a spin Hall angle at least about 0.05.
    Type: Application
    Filed: August 10, 2015
    Publication date: December 3, 2015
    Inventors: Robert A. Buhrman, Luqiao Liu, Daniel C. Ralph, Chi-Feng Pai
  • Patent number: 9105832
    Abstract: An ST-MRAM structure, a method for fabricating the ST-MRAM structure and a method for operating an ST-MRAM device that results from the ST-MRAM structure each utilize a spin Hall effect base layer that contacts a magnetic free layer and effects a magnetic moment switching within the magnetic free layer as a result of a lateral switching current within the spin Hall effect base layer. This resulting ST-MRAM device uses an independent sense current and sense voltage through a magnetoresistive stack that includes a pinned layer, a non-magnetic spacer layer and the magnetic free layer which contacts the spin Hall effect base layer. Desirable non-magnetic conductor materials for the spin Hall effect base layer include certain types of tantalum materials and tungsten materials that have a spin diffusion length no greater than about five times the thickness of the spin Hall effect base layer and a spin Hall angle at least about 0.05.
    Type: Grant
    Filed: August 17, 2012
    Date of Patent: August 11, 2015
    Assignee: Cornell University
    Inventors: Robert A. Buhrman, Luqiao Liu, Daniel C. Ralph, Chi-Feng Pai