Patents by Inventor Stuart Stephen Papworth Parkin

Stuart Stephen Papworth Parkin 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: 7357995
    Abstract: Magnetic tunneling devices are formed from a first body centered cubic (bcc) magnetic layer and a second bcc magnetic layer. At least one spacer layer of bcc material between these magnetic layers exchange couples the first and second bcc magnetic layers. A tunnel barrier in proximity with the second magnetic layer permits spin-polarized current to pass between the tunnel barrier and the second layer; the tunnel barrier may be either MgO and Mg—ZnO. The first magnetic layer, the spacer layer, the second magnetic layer, and the tunnel barrier are all preferably (100) oriented. The MgO and Mg—ZnO tunnel barriers are prepared by first depositing a metallic layer on the second magnetic layer (e.g., a Mg layer), thereby substantially reducing the oxygen content in this magnetic layer, which improves the performance of the tunnel barriers.
    Type: Grant
    Filed: July 2, 2004
    Date of Patent: April 15, 2008
    Assignee: International Business Machines Corporation
    Inventor: Stuart Stephen Papworth Parkin
  • Patent number: 7349187
    Abstract: Magnetic tunnel junctions are disclosed that include ferromagnetic (or ferrimagnetic) materials and a bilayer tunnel barrier structure that includes a layer of alkaline earth oxide. The bilayer also includes a layer of crystalline material, such as MgO or Mg—ZnO. If MgO is used, then it is preferably (100) oriented. The magnetic tunnel junctions so formed enjoy high tunneling magnetoresistance, e.g., much greater than 100% at room temperature.
    Type: Grant
    Filed: September 7, 2005
    Date of Patent: March 25, 2008
    Assignee: International Business Machines Corporation
    Inventor: Stuart Stephen Papworth Parkin
  • Patent number: 7345855
    Abstract: Magnetic tunnel junctions are disclosed that include ferromagnetic (or ferrimagnetic) materials and a bilayer tunnel barrier structure that includes a layer of a rare earth oxide. The bilayer also includes a layer of crystalline material, such as MgO or Mg—ZnO. If MgO is used, then it is preferably (100) oriented. The magnetic tunnel junctions so formed enjoy high tunneling magnetoresistance, e.g., much greater than 100% at room temperature.
    Type: Grant
    Filed: September 7, 2005
    Date of Patent: March 18, 2008
    Assignee: International Business Machines Corporation
    Inventor: Stuart Stephen Papworth Parkin
  • Publication number: 20080062581
    Abstract: Magnetic tunneling devices are formed from a first body centered cubic (bcc) magnetic layer and a second bcc magnetic layer. At least one spacer layer of bcc material between these magnetic layers exchange couples the first and second bcc magnetic layers. A tunnel barrier in proximity with the second magnetic layer permits spin-polarized current to pass between the tunnel barrier and the second layer; the tunnel barrier may be either MgO and Mg—ZnO. The first magnetic layer, the spacer layer, the second magnetic layer, and the tunnel barrier are all preferably (100) oriented. The MgO and Mg—ZnO tunnel barriers are prepared by first depositing a metallic layer on the second magnetic layer (e.g., a Mg layer), thereby substantially reducing the oxygen content in this magnetic layer, which improves the performance of the tunnel barriers.
    Type: Application
    Filed: July 2, 2004
    Publication date: March 13, 2008
    Inventor: Stuart Stephen Papworth Parkin
  • Patent number: 7313013
    Abstract: A spin-current switchable magnetic memory element (and method of fabricating the memory element) includes a plurality of magnetic layers having a perpendicular magnetic anisotropy component, at least one of the plurality of magnetic layers including an alloy of a rare-earth metal and a transition metal, and at least one barrier layer formed adjacent to at least one of the plurality of magnetic layers.
    Type: Grant
    Filed: November 18, 2004
    Date of Patent: December 25, 2007
    Assignee: International Business Machines Corporation
    Inventors: Jonathan Zanhong Sun, Stuart Stephen Papworth Parkin
  • Patent number: 7276384
    Abstract: A magnetic tunnel element that can be used, for example, as part of a read head or a magnetic memory cell, includes a first layer formed from an amorphous material, an amorphous tunnel barrier layer, and an interface layer between the first layer and the tunnel barrier layer. The interface layer is formed from a material that is crystalline when the material is in isolation from both the first layer and the tunnel barrier layer. Alternatively, the thickness of the interface layer is selected so that the interface layer is not crystalline. The first layer is formed from at least one material selected from the group consisting of amorphous ferromagnetic material, amorphous ferromagnetic materials, and amorphous non-magnetic materials. The interface layer is formed from a material selected from the group consisting of a ferromagnetic material and a ferrimagnetic material.
    Type: Grant
    Filed: June 13, 2005
    Date of Patent: October 2, 2007
    Assignee: International Business Machines Corporation
    Inventors: Stuart Stephen Papworth Parkin, Mahesh Govind Samant
  • Patent number: 7274080
    Abstract: A MgO tunnel barrier is sandwiched between semiconductor material on one side and a ferri- and/or ferromagnetic material on the other side to form a spintronic element. The semiconductor material may include GaAs, for example. The spintronic element may be used as a spin injection device by injecting charge carriers from the magnetic material into the MgO tunnel barrier and then into the semiconductor. Similarly, the spintronic element may be used as a detector or analyzer of spin-polarized charge carriers by flowing charge carriers from the surface of the semiconducting layer through the MgO tunnel barrier and into the (ferri- or ferro-) magnetic material, which then acts as a detector. The MgO tunnel barrier is preferably formed by forming a Mg layer on an underlayer (e.g., a ferromagnetic layer), and then directing additional Mg, in the presence of oxygen, towards the underlayer.
    Type: Grant
    Filed: October 19, 2004
    Date of Patent: September 25, 2007
    Assignee: International Business Machines Corporation
    Inventor: Stuart Stephen Papworth Parkin
  • Patent number: 7270896
    Abstract: A magnetic tunneling element is constructed from a MgO or Mg—ZnO tunnel barrier and an amorphous magnetic layer in proximity with the tunnel baffler. The amorphous magnetic layer includes Co and at least one additional element selected to make the layer amorphous. Magnetic tunnel junctions formed from the amorphous magnetic layer, the tunnel barrier, and an additional ferromagnetic layer have tunneling magnetoresistance values of up to 200% or more.
    Type: Grant
    Filed: July 2, 2004
    Date of Patent: September 18, 2007
    Assignee: International Business Machines Corporation
    Inventor: Stuart Stephen Papworth Parkin
  • Patent number: 7252852
    Abstract: ZnMg oxide tunnel barriers are grown which, when sandwiched between ferri- or ferromagnetic layers, form magnetic tunnel junctions exhibiting high tunneling magnetoresistance (TMR). The TMR may be increased by annealing the magnetic tunnel junctions. The zinc-magnesium oxide tunnel barriers may be incorporated into a variety of other devices, such as magnetic tunneling transistors and spin injector devices. The ZnMg oxide tunnel barriers are grown by first depositing a zinc and/or magnesium layer onto an underlying substrate in oxygen-poor (or oxygen-free) conditions, and subsequently depositing zinc and/or magnesium onto this layer in the presence of reactive oxygen.
    Type: Grant
    Filed: November 5, 2004
    Date of Patent: August 7, 2007
    Assignee: International Business Machines Corporation
    Inventor: Stuart Stephen Papworth Parkin
  • Patent number: 7230265
    Abstract: A tunnel barrier in proximity with a layer of a rare earth element-transition metal (RE—TM) alloy forms a device that passes negatively spin-polarized current. The rare earth element includes at least one element selected from the group consisting of Gd, Tb, Dy, Ho, Er, Tm, and Yb. The RE and TM have respective sub-network moments such that the absolute magnitude of the RE sub-network moment is greater than the absolute magnitude of the TM sub-network moment. An additional layer of magnetic material may be used in combination with the tunnel barrier and the RE—TM alloy layer to form a magnetic tunnel junction. Still other layers of tunnel barrier and magnetic material may be used in combination with the foregoing to form a flux-closed double tunnel junction device.
    Type: Grant
    Filed: May 16, 2005
    Date of Patent: June 12, 2007
    Assignee: International Business Machines Corporation
    Inventors: Christian Kaiser, Stuart Stephen Papworth Parkin
  • Patent number: 7192787
    Abstract: MRAMs are provided with cells offering low current leakage for partially selected cells. MRAM cells are made with magnetic tunnel junctions having barriers that meet predetermined low barrier heights and predetermined thicknesses. The barrier heights are preferably about 1.5 eV or less. The predetermined thicknesses are calculated to meet power and speed requirements. The predetermined low barrier heights and predetermined thicknesses modify a nonlinear term relating current through to voltage across the magnetic tunnel junction. The modification of the nonlinear term also modifies the amount of current that flows through a magnetic tunnel junction at various voltages. At low voltages, current through the magnetic tunnel junction will be disproportionately lower than current through a conventional magnetic tunnel junction. This decreases leakage current through partially selected MRAM cells and power.
    Type: Grant
    Filed: December 10, 2002
    Date of Patent: March 20, 2007
    Assignee: International Business Machines Corporation
    Inventors: John Kenneth DeBrosse, Yu Lu, Stuart Stephen Papworth Parkin
  • Patent number: 7149105
    Abstract: Methods of manufacturing MTJ memory cells and structures thereof. A diffusion barrier is disposed between an anti-ferromagnetic layer and a pinned layer of an MTJ memory cell to improve thermal stability of the MTJ memory cell. The diffusion barrier may comprise an amorphous material or a NiFe alloy. An amorphous material may be disposed adjacent a bottom surface of a tunnel junction, within a free layer, or both. An MTJ memory cell with improved thermal stability and decreased Neel coupling is achieved.
    Type: Grant
    Filed: February 24, 2004
    Date of Patent: December 12, 2006
    Assignees: Infineon Technologies AG, International Business Machines Corporation
    Inventors: Stephen L. Brown, Arunava Gupta, Ulrich Klostermann, Stuart Stephen Papworth Parkin, Wolfgang Raberg, Mahesh Samant
  • Publication number: 20040109347
    Abstract: MRAMs are provided with cells offering low current leakage for partially selected cells. MRAM cells are made with magnetic tunnel junctions having barriers that meet predetermined low barrier heights and predetermined thicknesses. The barrier heights are preferably about 1.5 eV or less. The predetermined thicknesses are calculated to meet power and speed requirements. The predetermined low barrier heights and predetermined thicknesses modify a nonlinear term relating current through to voltage across the magnetic tunnel junction. The modification of the nonlinear term also modifies the amount of current that flows through a magnetic tunnel junction at various voltages. At low voltages, current through the magnetic tunnel junction will be disproportionately lower than current through a conventional magnetic tunnel junction. This decreases leakage current through partially selected MRAM cells and power.
    Type: Application
    Filed: December 10, 2002
    Publication date: June 10, 2004
    Applicant: International Business Machines Corporation
    Inventors: John Kenneth DeBrosse, Yu Lu, Stuart Stephen Papworth Parkin
  • Publication number: 20040070890
    Abstract: The invention is a magnetic device that includes a ferromagnetic/antiferromagnetic (F/AF) structure wherein the ferromagnetic layer is perpendicularly exchange biased by the antiferromagnetic layer. The invention has application to perpendicular magnetic recording disks and magnetic tunnel junction devices used as read heads for disk drives and memory cells in magnetic memory arrays.
    Type: Application
    Filed: September 16, 2003
    Publication date: April 15, 2004
    Inventors: Eric Edward Fullerton, Stefan Maat, Stuart Stephen Papworth Parkin, Kentaro Takano
  • Patent number: 6650513
    Abstract: The invention is a magnetic device that includes a ferromagnetic/antiferromagnetic (F/AF) structure wherein the ferromagnetic layer is perpendicularly exchange biased by the antiferromagnetic layer. The invention has application to perpendicular magnetic recording disks and magnetic tunnel junction devices used as read heads for disk drives and memory cells in magnetic memory arrays.
    Type: Grant
    Filed: January 29, 2001
    Date of Patent: November 18, 2003
    Assignee: International Business Machines Corporation
    Inventors: Eric Edward Fullerton, Stefan Maat, Stuart Stephen Papworth Parkin, Kentaro Takano
  • Patent number: 6515897
    Abstract: A non-volatile memory array having a substrate, a first plurality of electrically conductive traces formed on the substrate, a second plurality of electrically conductive traces formed on the substrate and overlapping first plurality of traces at a plurality of intersection regions, and a plurality of memory cells. Each memory cell is located at an intersection region between one of the first plurality of traces and one of the second plurality of traces. At least one memory cell includes a non-linear magnetic tunnel junction storage element. The non-linear magnetic tunnel junction storage element has at least a first ferromagnetic layer, a barrier layer and a second ferromagnetic layer. The non-linear magnetic tunnel junction storage element has a non-linearity that is defined by a current having a first magnitude flowing through the non-linear magnetic tunnel junction storage element for a bias across the non-linear magnetic tunnel junction storage element of about 0.
    Type: Grant
    Filed: April 13, 2000
    Date of Patent: February 4, 2003
    Assignee: International Business Machines Corporation
    Inventors: Douwe Johannes Monsma, Stuart Stephen Papworth Parkin, Roy Edwin Scheuerlein
  • Patent number: 6452761
    Abstract: The current invention provides for magnetic sensor devices with reduced gap thickness and improved thermal conductivity. Gap structures of the current invention are integrated in laminated Magneto-Resistive and Spin-Valve sensors used in magnetic data storage systems. The gap structures are produced by depositing metal layers and oxidizing portions of or all of the metal layers to form thin high quality oxidized metal dielectric separator layers. The oxidized metal layer provides for excellent electrical insulation of the sensor element and any remaining metallic portions of the metal layers provide a thermally conducting pathway to assist the dissipation of heat generated by the sensor element. Because of the combined qualities of electrical insulation and thermal conductivity, magnetic sensor devices of this invention can be made with thinner gap structures and operated at higher drive currents.
    Type: Grant
    Filed: January 14, 2000
    Date of Patent: September 17, 2002
    Assignee: International Business Machines Corporation
    Inventors: Matthew Joseph Carey, Jeffrey Robinson Childress, Robert Edward Fontana, Jr., Bruce Alvin Gurney, Stuart Stephen Papworth-Parkin, Ren Xu
  • Publication number: 20020101692
    Abstract: The invention is a magnetic device that includes a ferromagnetic/antiferromagnetic (F/AF) structure wherein the ferromagnetic layer is perpendicularly exchange biased by the antiferromagnetic layer. The invention has application to perpendicular magnetic recording disks and magnetic tunnel junction devices used as read heads for disk drives and memory cells in magnetic memory arrays.
    Type: Application
    Filed: January 29, 2001
    Publication date: August 1, 2002
    Applicant: International Business Machines Corporation
    Inventors: Eric Edward Fullerton, Stefan Maat, Stuart Stephen Papworth Parkin, Kentaro Takano
  • Patent number: 6359289
    Abstract: A magnetic tunnel junction device has a tunnel barrier made of a material consisting essentially of an oxide or nitride of one or more of gallium and indium. An oxide or nitride of aluminum may be included as part of this tunnel barrier material. In one embodiment the tunnel barrier is an oxide of a gallium-aluminum alloy (Ga75Al25). The Ga oxide tunnel barrier may be formed by sputter deposition of Ga, followed by a plasma oxidation, or by depositing Ga from an effusion source in the presence of oxygen gas or in the presence of more reactive oxygen provided by an atomic oxygen source or other source. The tunnel barrier layer may also be formed as a bi-layer structure with an aluminum oxide layer formed directly on one of the ferromagnetic layers of the device, followed by a gallium oxide layer formed directly on the aluminum oxide layer.
    Type: Grant
    Filed: April 19, 2000
    Date of Patent: March 19, 2002
    Assignee: International Business Machines Corporation
    Inventor: Stuart Stephen Papworth Parkin
  • Patent number: 6331944
    Abstract: A non-volatile memory array includes first and second pluralities of electrically conductive traces formed on a substrate. The second plurality of electrically conductive traces overlap first plurality of traces at a plurality of intersection regions. Each of a plurality of memory cells is located at an intersection region between one of the first plurality of traces and one of the second plurality of traces. At least one of the memory cells includes a non-linear selection element in series with a magnetic tunnel junction storage element. The non-linear selection element includes at least a first metallic electrode layer, a barrier layer and a second metallic electrode layer metal.
    Type: Grant
    Filed: April 13, 2000
    Date of Patent: December 18, 2001
    Assignee: International Business Machines Corporation
    Inventors: Douwe Johannes Monsma, Stuart Stephen Papworth Parkin, Roy Edwin Scheuerlein