Having Multiple Interconnected Multiple Film Mr Sensors (e.g., Dual Spin Valve Magnetoresistive Sensor) Patents (Class 360/314)
  • Patent number: 6407890
    Abstract: A specular reflector film of iron oxide is located between ferromagnetic first and second pinned films in a pinned layer for reflecting conduction electrons back for spin dependent scattering for improving the magnetoresistive coefficient of a spin valve sensor. The specular reflector film is preferably &ggr;Fe2O3 since this material is a magnetic phase of iron oxide and will contribute to the magnetic moment of the pinned layer. In a preferred embodiment a dual spin valve sensor is employed wherein a pinned layer with a specular reflector film is located on each side of a free layer structure for reflecting conduction electrons from both sides of the free layer structure. Still further, it is preferred that each pinned layer be an antiparallel (AP) pinned layer structure with a specular reflector film embedded in one of the AP pinned layers of each AP pinned layer structure.
    Type: Grant
    Filed: February 8, 2000
    Date of Patent: June 18, 2002
    Assignee: International Business Machines Corporation
    Inventor: Hardayal Singh Gill
  • Publication number: 20020067577
    Abstract: A dual spin valve sensor is provided which is file resettable. An antiparallel (AP) coupled free layer structure is located between first and second pinned layer structures. The AP coupled free layer structure includes an AP coupling layer between first and second AP coupled free layers. When a current pulse is conducted through a sense current circuit the temperature of the sensor increases and conductive layers of the spin valve sensor exert current fields on the first and second pinned structures which set the magnetic spins of first and second antiferromagnetic pinning layers exchange coupled thereto. When the current pulse is terminated or reduced and the sensor cools the first and second pinning layers pin the magnetic moments of the first and second pinned layers antiparallel with respect to each other.
    Type: Application
    Filed: August 5, 1999
    Publication date: June 6, 2002
    Inventors: ROBERT STANLEY BEACH, MATTHEW CAREY, BRUCE A. GURNEY
  • Patent number: 6396668
    Abstract: A planar spin valve read head comprises a top and a bottom shield, and a first and a second gap layer. The first gap layer is positioned adjacent to the bottom shield. The second gap layer is positioned adjacent to the top shield. The read head includes a planar sensor structure positioned between the first and the second gap layers for sensing a magnetic field from a magnetic medium.
    Type: Grant
    Filed: July 24, 2000
    Date of Patent: May 28, 2002
    Assignee: Seagate Technology LLC
    Inventors: Sining Mao, Dian Song
  • Patent number: 6392849
    Abstract: It is the object of the invention to provide a magnetic head and a magnetic storage apparatus using the magnetic head provided with a signal reproducing means which is capable of using the same signal processing circuit as used for the conventional longitudinal magnetization film type recording medium even when a perpendicular magnetization film type recording medium is used. Because the present invention renders the reproducing signal generated from a perpendicular magnetization film Gaussian shaped (Lorentizian pulse), the same signal processing circuit as used for the conventional longitudinal magnetization film type recording medium can be used.
    Type: Grant
    Filed: February 22, 2001
    Date of Patent: May 21, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Yoji Maruyama, Yoshio Suzuki, Ryoichi Nakatani, Hisashi Takano
  • Patent number: 6392853
    Abstract: The giant magnetoresistance (GMR) effect includes a contribution that is due to anisotropic magnetoresistance (AMR). Unfortunately the AMR effect tends to degrade the peak-to-peak signal asymmetry. Additionally, a high AMR/GMR ratio causes a larger signal asymmetry variation. It is therefor desirable to reduce both the AMR contribution as well as the AMR/GMR ratio. This has been achieved by modifying the free layer through the insertion of an extra layer of a highly resistive or insulating material at approximately mid thickness level. This layer is from 3 to 15 Angstroms thick and serves to reduce the Anisotropic Magneto-resistance contribution to the total magneto-resistance of the device. This reduces the GMR contribution only slightly but cuts the AMR/GMR ratio in half, thereby improving cross-track asymmetry and signal linearity.
    Type: Grant
    Filed: January 24, 2000
    Date of Patent: May 21, 2002
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Simon H. Liao, Cheng T. Horng, Youfeng Zheng, Ru-Ying Tong, Kochan Ju
  • Patent number: 6381105
    Abstract: A hybrid dual spin valve sensor includes a standard spin valve sharing a common free layer with a synthetic spin valve. The standard spin valve consists of a first antiferromagnetic layer having a first blocking temperature, a first soft ferromagnetic layer, a first spacer layer, and the common free layer. The synthetic spin valve consists of the common free layer, a second spacer, a second soft ferromagnetic layer, a third spacer layer, a third soft ferromagnetic layer, and a second antiferromagnetic layer having a second blocking temperature. Each of the two antiferromagnetic layers has a fixed magnetization orientation antiparallel to the other. A lead set configured to pass a sensing current from a current source through the hybrid dual spin valve, and a sensing circuit configured to measure changes in resistance within the hybrid dual spin valve, complete the sensor.
    Type: Grant
    Filed: October 22, 1999
    Date of Patent: April 30, 2002
    Assignee: Read-Rite Corporation
    Inventors: Yiming Huai, Geoff Anderson, Mahendra Pakala, Wenjie Chen, Ningjia Zhu
  • Publication number: 20020044389
    Abstract: A differential sensor for reading data from a magnetic medium is disclosed. The sensor comprises two GMR multilayer structures biased in opposite directions, such as to show the transitions between binary states recorded on the media as the media flows under the sensor. The biasing of the GMR structures can be accomplished using a synthetic-antiferromagnet.
    Type: Application
    Filed: January 13, 2002
    Publication date: April 18, 2002
    Inventors: Michael Allen Seigler, Gregory John Parker
  • Publication number: 20020044396
    Abstract: A TMR device comprising an antiferromagnetic layer made of an antiferromagnetic material containing Mn, a magnetization fixed layer made of a ferromagnetic material, a tunnel barrier layer made of a dielectric material, and a magnetization free layer made of a ferromagnetic material. An insulator material layer is inserted in the magnetization fixed layer at a distance from the antiferromagnetic material layer and the tunnel barrier layer. One material can be expressed by NX, where X is a first element selected from the group consisting of oxygen, nitrogen and carbon; and N is a second element, provided that the bonding energy between the first and the second elements is higher than the bonding energy between manganese and the first element. A second material can be expressed by MX, where M is an element selected from the group consisting of titanium, tantalum, vanadium, aluminum, europium, and scandium; and X is an element selected from the group consisting of oxygen, nitrogen and carbon.
    Type: Application
    Filed: September 4, 2001
    Publication date: April 18, 2002
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Minoru Amano, Yoshiaki Saito
  • Patent number: 6370763
    Abstract: Disclosed is a magnetic head manufacturing method for accurately measuring resistance value whereby magnetic heads are processed while measuring the resistance values of process monitoring element. After forming on a wafer magnetic head elements and monitoring element, in which resistance values change in analog fashion in line with processing, these elements are cut from the wafer. Next, the magnetic heads are processed to a prescribed height while measuring the resistance values of the monitoring element. In the forming process, the difference &Dgr;I between the positions of the magnetic head elements and monitoring element is measured in advance, and this difference &Dgr;I is used to convert the resistance values of the monitoring element to the height of the magnetic head elements. This makes it possible to correct errors in masks. Furthermore, patterns can be formed accurately by setting the position of the monitoring element to the same position as the magnetoresistive film of the magnetic heads.
    Type: Grant
    Filed: October 27, 1997
    Date of Patent: April 16, 2002
    Assignee: Fujitsu Limited
    Inventors: Motoichi Watanuki, Tomokazu Sugiyama, Kazuo Yokoi, Yoshiaki Yanagida, Koji Suto
  • Publication number: 20020024778
    Abstract: The invention includes spin valve sensors. The spin valve sensors of the invention can be dual spin valves, bottom pinned spin valves, or top pinned spin valves. Spin valve sensor in accordance with the invention include a cap layer of tantalum nitride and a free layer. Cap layers of the invention include both monolayers and bilayers. Monolayer cap layers are tantalum nitride, and bilayer cap layers are a first layer of tantalum nitride with a layer of copper, ruthenium, gold, or silver thereon.
    Type: Application
    Filed: March 15, 2001
    Publication date: February 28, 2002
    Inventors: Song Sheng Xue, Xuefei Tang, Qing He, Steven Paul Bozeman, Patrick Joseph Ryan
  • Publication number: 20020024775
    Abstract: The present invention provides a spin valve thin film magnetic element capable of preventing the occurrence of side reading, and a method of manufacturing the same. In the spin valve thin film magnetic element, nonmagnetic conductive layers, pinned magnetic layers and antiferromagnetic layers are laminated on both sides of a free magnetic layer in the thickness direction to form a laminate on a substrate. Also, bias layers and lead layers are provided on both sides of the laminate in the track width direction. Of the antiferromagnetic layers, at least the antiferromagnetic layer apart from the substrate is made narrower than the free magnetic layer in the track width direction to form lead connecting portions of the laminate on both sides of the narrow antiferromagnetic layer in the track width direction. The lead layers are formed to extend from both sides of the laminate in the track width direction to the center thereon and to be connected to the laminate 12 through the lead connecting portions.
    Type: Application
    Filed: August 21, 2001
    Publication date: February 28, 2002
    Applicant: Alps Electric Co., Ltd.
    Inventor: Naoya Hasegawa
  • Publication number: 20020018323
    Abstract: This invention presents a method and system for fabricating a dual GMR read head, which possess a pseudo spin valve structure. The spin valve structure includes a first thick Co-alloy based reference layer with first and second surfaces. The structure includes a first spacer layer including a first surface contacting the first surface of the first thick Co-alloy layer and a second surface contacting a first surface of a first free layer. The structure also includes a second spacer layer including a first surface separated from the second surface of the first free layer and a second surface contacting a first surface of a second thick Co-alloy layer. The thickness of the first and second thick Co-based alloy can be approximately between 30 and 55 Å.
    Type: Application
    Filed: April 12, 2001
    Publication date: February 14, 2002
    Inventors: Shaoping Li, Charles Potter
  • Patent number: 6347022
    Abstract: A spin-valve type magnetoresistive thin film head is provided with a spin-valve type magnetoresistive thin film element which includes a free magnetic layer; an upper nonmagnetic electrically-conductive layer and a lower nonmagnetic electrically-conductive layer sandwiching the free magnetic layer; an upper pinned magnetic layer and a lower pinned magnetic layer formed on the upper and lower nonmagnetic electrically-conductive layers, respectively, the magnetization directions of the upper and lower pinned magnetic layers being fixed; and an upper antiferromagnetic layer and a lower antiferromagnetic layer formed on the upper and lower pinned magnetic layers, respectively; in which a sensing electric current is applied in the direction perpendicular to the fixed magnetization of the pinned magnetic layers, and electrical resistance changes in response to the relationship between the fixed magnetization of the pinned magnetic layers and the variable magnetization of the free magnetic layer.
    Type: Grant
    Filed: July 22, 1999
    Date of Patent: February 12, 2002
    Assignee: Alps Electric Co., Ltd.
    Inventor: Masamichi Saito
  • Publication number: 20010053053
    Abstract: An exchange coupling film has an antiferromagnetic layer, a pinned magnetic layer, and a seed layer provided on the side of the antiferromagnetic layer 4 opposite to the pinned magnetic layer. The seed layer has a crystalline structure constituted mainly by face-centered cubic crystals with (111) planes substantially aligned. The seed layer is preferably non-magnetic. A laminate structure including the antiferromagnetic layer and a free layer inclusive of the intervening layers have crystalline orientations with their (111) planes substantially aligned, so that large crystal grains and, hence, large ratio of resistance variation can be achieved.
    Type: Application
    Filed: April 11, 2001
    Publication date: December 20, 2001
    Inventors: Masamichi Saito, Naoya Hasegawa, Yosuke Ide, Kenichi Tanaka
  • Publication number: 20010043447
    Abstract: The magnetic moment of a first pinned magnetic layer is greater than the magnetic moment of a second pinned magnetic layer, and the magnetic moment of the first pinned magnetic layer faces in the left direction in the drawing. Accordingly, the synthesized magnetic moment of the first pinned magnetic layer and the second pinned magnetic layer faces in the left direction in the drawing. Thus, causing a sensing current to flow in the direction shown by X in the Figure so as to generate a sensing galvanomagnetic field circling in the right-hand direction causes the direction of the sensing galvanomagnetic field and the direction of the synthesized magnetic moment to match, thereby facilitating improvement in the stability of the magnetization state of the first and second pinned magnetic layers.
    Type: Application
    Filed: May 18, 2001
    Publication date: November 22, 2001
    Inventors: Masamichi Saito, Naoya Hasegawa
  • Publication number: 20010040774
    Abstract: A method and system for providing a dual spin valve is disclosed. The dual spin valve is for reading data in a magnetic recording media. The method and system include providing a first pinned layer. The first pinned layer has a first magnetization. The method and system also include providing a CoFe free layer and providing a first nonmagnetic spacer layer. The first nonmagnetic spacer layer is between the first pinned layer and the CoFe free layer. The method and system also include providing a second pinned layer and a second nonmagnetic spacer layer. The second pinned layer has a second magnetization. The second nonmagnetic spacer layer is between the CoFe free layer and the second pinned layer.
    Type: Application
    Filed: August 18, 1999
    Publication date: November 15, 2001
    Applicant: Read-Rite Corporation
    Inventors: SHIN FUNADA, MING MAO, HUA-CHING TONG
  • Patent number: 6317297
    Abstract: A method and system for providing a magnetoresistive sensor is disclosed. The method and system include providing a first pinned layer, providing a first spacer layer above the first pinned layer, and providing a free layer above the first spacer layer. The method and system further include providing a second spacer layer above the free layer and providing a second pinned layer above the second spacer layer. The first pinned layer includes a first magnetic layer and a second magnetic layer separated by a first nonmagnetic layer. The first magnetic layer is antiferromagnetically coupled with the second magnetic layer. The second pinned layer includes a third magnetic layer and a fourth magnetic layer separated by a second nonmagnetic layer. The third magnetic layer is antiferromagnetically coupled with the fourth magnetic layer. The first pinned layer and the second pinned layer are pinned by a current carried by the magnetoresistive head during use.
    Type: Grant
    Filed: October 6, 1999
    Date of Patent: November 13, 2001
    Assignee: Read-Rite Corporation
    Inventors: Hua-Ching Tong, Xizeng Shi, Subrata Dey, Matthew Richard Gibbons
  • Publication number: 20010038516
    Abstract: A magnetoresistive device includes a metal layer, formed over a substrate, in which a groove is formed. A magnetoresistive element is formed in the groove, forming two magnetoresistive element portions that are separated by a conductive element. A sense current applied to the metal layer flows through the two magnetoresistive element portions with a predominant current-perpendicular-to-plane component. A method includes techniques that are less complex and less expensive than submicron photolithography to form the above described magnetoresistive device with submicron geometries. A system includes a read/write head that incorporates a magnetoresistive element formed in a groove of a metal layer.
    Type: Application
    Filed: February 20, 2001
    Publication date: November 8, 2001
    Applicant: Read-Rite Corporation
    Inventors: Kenneth E. Knapp, Ronald A. Barr
  • Publication number: 20010033465
    Abstract: There is disclosed a magnetoresistive head in which an interlayer coupling field Hin applied to a free magnetic layer is minimized. The magnetoresistive head is provided with a magnetoresistive film including: a first antiferromagnetic layer 2; a pinned magnetic layer 3 formed on the first antiferromagnetic layer 2 and provided with magnetization whose direction is fixed; a first nonmagnetic layer 4 formed on the pinned magnetic layer 3; a free magnetic layer 5 formed on the first nonmagnetic layer 4 and provided with magnetization whose direction changes in accordance with an external magnetic field; a second nonmagnetic layer 6 formed on the free magnetic layer 5; and a second antiferromagnetic layer 7, formed on the second nonmagnetic layer 6, for applying a bias magnetic field generated by static interlayer coupling and directed in a direction opposite to magnetization direction of the pinned magnetic layer 3 to the free magnetic layer 5.
    Type: Application
    Filed: December 4, 2000
    Publication date: October 25, 2001
    Applicant: FUJITSU LIMITED
    Inventors: Kenji Noma, Hitoshi Kanai
  • Publication number: 20010030839
    Abstract: A dual spin-valve magnetoresistive sensor includes a free ferromagnetic layer and first and second nonmagnetic conductive spacers adjacent to opposing first and second surfaces of the free layer, respectively. A pinned ferromagnetic layer consisting of a single-film ferromagnetic layer is adjacent to the first spacer and a laminated pinned ferromagnetic structure is adjacent to the second spacer. The laminated structure includes first and second pinned ferromagnetic films separated by a film that provides antiferromagnetic coupling. First and second antiferromagnetic layers can be provided adjacent to the pinned ferromagnetic layer and the laminated pinned structure, respectively. The sensor can be incorporated, for example, into a magnetic storage system.
    Type: Application
    Filed: January 10, 2001
    Publication date: October 18, 2001
    Inventors: Lieping Zhong, Jian Chen, Juan Jose Fernandez-De-Castro
  • Publication number: 20010028537
    Abstract: A triple antiparallel (AP) coupled free layer structure is located between first and second pinned layer structures in a dual spin valve sensor. The triple AP coupled free layer structure includes first, second and third antiparallel (AP) coupled ferromagnetic free layers and nonmagnetic first and second antiparallel (AP) coupling layers. The first AP coupling layer is located between and interfaces the first and second AP coupled free layers and the second AP coupling layer is located between and interfaces the second and third AP coupled free layers. Magnetic moments of the first and third AP coupled free layers are parallel with respect to one another and, because of a strong antiparallel coupling, the second AP coupled free layer pins magnetic moments of the first and third AP coupled free layers antiparallel thereto.
    Type: Application
    Filed: June 1, 2001
    Publication date: October 11, 2001
    Inventor: Hardayal Singh Gill
  • Patent number: 6301089
    Abstract: A spin-valve type magnetoresistive thin film element includes at least one antiferromagnetic layer, a pinned magnetic layer in contact with the antiferromagnetic layer, a nonmagnetic electrically conductive layer formed on the pinned magnetic layer, with a free magnetic layer formed thereon, a bias layer for orienting the magnetization of the free magnetic layer to a direction intersecting the magnetization direction of the pinned magnetic layer, and an electrically conductive layer for supplying a sensing current to the pinned magnetic layer, the nonmagnetic electrically conductive layer and the free magnetic layer. The free magnetic layer is composed of a NiFe alloy film and has a thickness in a range of 30 to 100 Å. When the composition of the NiFe alloy is properly determined, the magnetostriction constant of the free magnetic layer can be controlled to be −2×10−6to 1×10−6, and more preferably −0.
    Type: Grant
    Filed: August 2, 1999
    Date of Patent: October 9, 2001
    Assignee: Alps Electric Co., Ltd.
    Inventors: Masamichi Saito, Naoya Hasegawa
  • Patent number: 6295718
    Abstract: Within a method for forming a magnetoresistive (MR) sensor element there is first provided a substrate. There is then formed over the substrate a first magnetoresistive (MR) layer having formed contacting the first magnetoresistive (MR) layer a magnetically biased first magnetic bias layer biased in a first magnetic bias direction with a first magnetic bias field strength. There is also formed separated from the first magnetoresistive (MR) layer by a spacer layer a second magnetoresistive (MR) layer having formed contacting the second magnetoresistive (MR) layer a magnetically un-biased second magnetic bias layer.
    Type: Grant
    Filed: August 16, 1999
    Date of Patent: October 2, 2001
    Assignee: Headway Technologies, Inc.
    Inventors: Min Li, Simon H. Liao
  • Patent number: 6295187
    Abstract: A spin valve sensor has a pinned layer structure that has a net positive stress induced uniaxial anisotropy that promotes a pinning of the pinned layer structure in a pinned direction for stabilizing the pinning of the pinned layer structure at high temperatures near to a blocking temperature of a pinning layer which is exchange coupled to the pinned layer.
    Type: Grant
    Filed: June 29, 1999
    Date of Patent: September 25, 2001
    Assignee: International Business Machines Corporation
    Inventor: Mustafa Pinarbasi
  • Patent number: 6278589
    Abstract: A dual GMR sensor with a single antiferromagnetic (AFM) pinned layer is provided which has a thinner overall stack thickness and additive spin valve effects to increase the sensitivity of the dual sensor and counterbiasing of the free layers of the dual sensor so as to render the sensor insensitive to a magnitude and orientation of a sense current. The single pinning layer reduces the thickness of the dual sensor permitting the employment of an antiparallel (AP) pinned layer structure for each of the spin valve sensors of the dual sensor. Further, a preferred material for the pinning layer is iridium manganese (IrMn) which reduces the pinning layer to 50 Å-80 Å.
    Type: Grant
    Filed: March 30, 1999
    Date of Patent: August 21, 2001
    Assignee: International Business Machines Corporation
    Inventor: Hardayal Singh Gill
  • Publication number: 20010014000
    Abstract: A spin-valve thin-film magnetic element has a composite provided on a substrate. The composite includes an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer. The composite also has bias layers and electrode layers on two sides thereof. The hard bias layers magnetize the free magnetic layer in a direction perpendicular to the pinned magnetic layer. The free magnetic layer is composed of a single CoFe-based alloy. The average crystal grain diameter in the free magnetic layer is 150 angstroms or less in the planar direction of the free magnetic layer. The volume of the crystal grains in which the <111> direction is predominantly oriented in a direction perpendicular to the planar direction of the free magnetic layer is 50 percent or less of the free magnetic layer.
    Type: Application
    Filed: January 30, 2001
    Publication date: August 16, 2001
    Applicant: Alps Electric Co., Ltd.
    Inventors: Kenichi Tanaka, Masamichi Saito, Yosuke Ide, Naoya Hasegawa
  • Publication number: 20010013999
    Abstract: A first layer region of a magnetically pinned layer in a spin valve structure, which is relatively remoter from a non-magnetic intermediate layer, is made of a ferromagnetic material containing at least one element selected from the group consisting of Cr (chrome), Rh (rhodium), Os (osmium), Re (rhenium), Si (silicon), Al (aluminum), Be (beryllium), Ga (gallium), Ge (germanium), Te (tellurium), B (boron), V (vanadium), Ru (ruthenium), Ir (iridium), W (tungsten), Mo (molybdenum), Au (gold), Pt (platinum), Ag (silver) and Cu (copper). Thereby, it is possible to provide a structure of the magnetically pinned layer, which can be readily made using a conventional deposition method and can ensure a sufficient electron reflecting effect on the part of the magnetically pinned layer, and to provide a magnetoresistive element using a spin valve film including the particular structure.
    Type: Application
    Filed: December 28, 2000
    Publication date: August 16, 2001
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Katsuhiko Koi, Hitoshi Iwasaki, Yuzo Kamiguchi, Hiromi Fuke, Hideaki Fukuzawa
  • Patent number: 6271997
    Abstract: A triple antiparallel (AP) coupled free layer structure is located between first and second pinned layer structures in a dual spin valve sensor. The triple AP coupled free layer structure includes first, second and third antiparallel (AP) coupled ferromagnetic free layers and nonmagnetic first and second antiparallel (AP) coupling layers. The first AP coupling layer is located between and interfaces the first and second AP coupled free layers and the second AP coupling layer is located between and interfaces the second and third AP coupled free layers. Magnetic moments of the first and third AP coupled free layers are parallel with respect to one another and, because of a strong antiparallel coupling, the second AP coupled free layer pins magnetic moments of the first and third AP coupled free layers antiparallel thereto.
    Type: Grant
    Filed: November 22, 1999
    Date of Patent: August 7, 2001
    Assignee: International Business Machines Corporation
    Inventor: Hardayal Singh Gill
  • Publication number: 20010009063
    Abstract: A spin valve thin-film magnetic device is provided, in which the asymmetry can be reduced. The spin valve thin-film magnetic device comprises a free magnetic layer and a first and a second fixed magnetic layer, which are provided respectively at each side of the free magnetic layer in the thickness direction thereof. In the spin valve thin-film magnetic device, the free magnetic layer is composed of a first and a second ferromagnetic free layer, in which the entire free magnetic layer is in a ferrimagnetic state, the first fixed magnetic layer is composed of a first and a second pinned ferromagnetic layer, in which the entire first fixed magnetic layer is in a ferrimagnetic state, and the second fixed magnetic layer is composed of a third and a fourth pinned ferromagnetic layer, in which the entire second fixed magnetic layer is in a ferrimagnetic state.
    Type: Application
    Filed: January 17, 2001
    Publication date: July 26, 2001
    Applicant: Alps Electric Co., Ltd.
    Inventors: Masamichi Saito, Kenichi Tanaka, Yosuke Ide, Fumihito Koike, Naoya Hasegawa
  • Patent number: 6259586
    Abstract: A differential magnetic tunnel junction (MTJ) sensor is provided having a first MTJ stack, a second MTJ stack and a common AP-coupled free layer. The AP-coupled free layer comprises a ferromagnetic first sense layer and a ferromagnetic second sense layer with an antiferromagnetic coupling (APC) layer disposed between the two sense layers providing strong antiferromagnetic coupling. The thickness of the first sense layer is chosen to be different (greater or smaller) than the thickness of the second sense layer so that the AP-coupled free layer has a net magnetic moment oriented parallel to the ABS and free to rotate in the presence of a signal magnetic field. Antiferromagnetic (AFM) layers in the first and second MTJ stacks are set to pin the magnetizations of pinned layers in each stack perpendicular to the ABS and in the same direction with respect to one another.
    Type: Grant
    Filed: September 2, 1999
    Date of Patent: July 10, 2001
    Assignee: International Business Machines Corporation
    Inventor: Hardayal (Harry) Singh Gill
  • Publication number: 20010006443
    Abstract: It is the object of the invention to provide a magnetic head and a magnetic storage apparatus using the magnetic head provided with a signal reproducing means which is capable of using the same signal processing circuit as used for the conventional longitudinal magnetization film type recording medium even when a perpendicular magnetization film type recording medium is used. Because the present invention renders the reproducing signal generated from a perpendicular magnetization film Gaussian shaped (Lorentzian pulse), the same signal processing circuit as used for the conventional longitudinal magnetization film type recording medium can be used.
    Type: Application
    Filed: February 22, 2001
    Publication date: July 5, 2001
    Inventors: Yoji Maruyama, Yoshio Suzuki, Ryoichi Nakatani, Hisashi Takano
  • Publication number: 20010004798
    Abstract: A dual GMR or dual spin valve sensor has a self-pinned layer which has its magnetic moment pinned perpendicular to an air bearing surface by sense current fields from conductive layers in the dual spin valve sensor when a sense current is conducted therethrough. This scheme eliminates one of the antiferromagnetic pinning layers which is typically employed in a dual GMR or dual spin valve sensor. The self-pinned layer is thin so that its demagnetization field will not be greater than the sense current fields acting thereon. Because of the thinning of the self-pinned layer the spin valve effect of the spin valve sensor is degraded by scattering of conduction electrons at the boundary of the self-pinned layer.
    Type: Application
    Filed: January 16, 2001
    Publication date: June 28, 2001
    Inventor: Hardayal Singh Gill
  • Patent number: 6191925
    Abstract: A magnetoresistive element for a dual element read head should exhibit uniform current density for proper biasing and Barkhausen noise limiting. Each element is a thin film MR layer normal to the magnetic media. Each element includes a front edge parallel with the magnetic media surface. A back edge, longer than the front edge, is opposite the front edge. Conductors through which current enters and exits the MR layer are adjacent to either end of the back edge.
    Type: Grant
    Filed: June 18, 1999
    Date of Patent: February 20, 2001
    Assignee: Storage Technology Corporation
    Inventor: Mark L. Watson
  • Patent number: 6191577
    Abstract: A magnetoresistive sensor includes a plurality of multilayered magnetoresistive films arranged in parallel. Each multilayered magnetoresistive film includes at least one pinned ferromagnetic layer and at least one free magnetic layer. Reversion of magnetization of the pinned ferromagnetic layer is pinned, whereas the vector of magnetization of the free ferromagnetic layer freely reverses in response to an external magnetic field. The vectors of magnetization of the pinned ferromagnetic layers in two adjacent multilayered magnetoresistive films are substantially antiparallel to each other.
    Type: Grant
    Filed: March 6, 1998
    Date of Patent: February 20, 2001
    Assignee: Alps Electric Co., Ltd.
    Inventors: Yoshito Sasaki, Naoya Hasegawa, Akihiro Makino, Ichiro Tokunaga, Seiji Kikuchi
  • Patent number: 6118638
    Abstract: A magnetoresistive device includes a metal layer, formed over a substrate, in which a groove is formed. A magnetoresistive element is formed in the groove, forming two magnetoresistive element portions that are separated by a conductive element. A sense current applied to the metal layer flows through the two magnetoresistive element portions with a predominant current-perpendicular-to-plane component. A method includes techniques that are less complex and less expensive than submicron photolithography to form the above described magnetoresistive device with submicron geometries. A system includes a read/write head that incorporates a magnetoresistive element formed in a groove of a metal layer.
    Type: Grant
    Filed: November 2, 1998
    Date of Patent: September 12, 2000
    Assignee: Read-Rite Corporation
    Inventors: Kenneth E. Knapp, Ronald A. Barr