William H Gallagher

US Patent:

6368878, Apr 9, 2002

Filed:

Mar 21, 2000

Appl. No.:

09/531715

Inventors:

David William Abraham - Ossining NY
William Joseph Gallagher - Ardsley NY
Philip Louis Trouilloud - Mahwah NJ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H01L 2100

US Classification:

438 3, 438 48

Abstract:

Magnetic memory cells include a changeable magnetic region with a magnetic axis along which two directions of magnetization can be imposed, thereby providing two respective states into which the cells are changeable according to electrical and resultant magnetic stimuli applied thereto. Asymmetry in the magnetic stimuli applied to the cell while writing a state therein is disclosed to provide a predictable magnetization pattern evolution from the first direction to the second direction. Physical asymmetry in the layout and/or magnetization of the cell is also disclosed which provides the predictable pattern evolution. These principles can be applied to magnetic random access memory (MRAM) arrays which employ magnetic tunnel junction (MTJ) cells at the intersections of bitlines and wordlines which supply the electrical and resultant magnetic stimuli to write the cells therein.

US Patent:

6392156, May 21, 2002

Filed:

Feb 28, 1995

Appl. No.:

08/396288

Inventors:

Arthur Davidson - Yorktown Heights NY
Timothy Rea Dinger - Chappaqua NY
William Joseph Gallagher - Ardsley NY
Thomas Kimber Worthington - New York NY

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

H01B 1200

US Classification:

1741251, 335216

Abstract:

Improved conductors and superconducting magnets are described utilizing superconducting materials exhibiting critical field anisotropy. This anisotropy is one in which the ability of the superconductor to stay in a superconducting state depends on the orientation of a magnetic field applied to the superconductor with respect to the direction of current flow in the superconductor. This anisotropy is utilized in the design of conductors and magnet windings comprising the superconductive material and specifically is directed to magnet windings in which the direction of high critical current through the superconductor is parallel to the magnetic field produced by current in these windings in order to obtain high critical fields. Particularly favorable examples of a superconducting material are the so-called high T superconductors in which the primary supercurrent flow is confined to 2 dimensional CuâO planes. By arranging the superconductive windings so that the CuâO planes are substantially parallel to the magnetic field produced by current in these windings, the windings will be able to withstand high fields without being driven normal.

US Patent:

6452764, Sep 17, 2002

Filed:

Oct 16, 2000

Appl. No.:

09/688732

Inventors:

David William Abraham - Ossining NY
Philip Edward Batson - Katonah NY
William Joseph Gallagher - Ardsley NY
Stuart Parkin - San Jose CA
John Slonczewski - Katonah NY
Philip Louis Trouilloud - Mahwah NJ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 539

US Classification:

3603242, 365173

Abstract:

Magnetoresistive devices are disclosed which include a changeable magnetic region within which at least two magnetic states can be imposed. Upon magnetoresistive electrical interaction with the device, the relative orientation of the magnetic states of the changeable magnetic region, and a proximate reference magnetic region, can be sensed thereby providing a binary data storage capability. The present invention limits the electrical interaction to only a preferred portion of the changeable magnetic region, e. g. , the portion within which the two magnetic states can be dependably predicted to be substantially uniform, and opposite of one another. Structures for limiting the electrical interaction to this preferred portion of the changeable magnetic region are disclosed, and include smaller interaction regions, and alternating areas of insulation and conductive, interaction regions, disposed proximate the changeable magnetic region. The principles of the present invention can be applied to magnetic random access memory (âMRAMâ) arrays, which employ giant magnetoresistive (âGMRâ) cells, or magnetic tunnel junction (âMTJâ) cells, at the intersections of bitlines and wordlines, and also to magnetic sensors such as magnetic data storage devices having access elements used to access data on a magnetic data storage medium.

US Patent:

6590750, Jul 8, 2003

Filed:

Feb 10, 1998

Appl. No.:

09/021352

Inventors:

David William Abraham - Ossining NY
Philip Edward Batson - Katonah NY
John Slonczewski - Katonah NY
Philip Louis Trouilloud - Mahwah NJ
William Joseph Gallagher - Ardsley NY
Stuart Parkin - San Jose CA

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11B 539

US Classification:

3603242, 3603241

Abstract:

Magnetoresistive devices are disclosed which include a changeable magnetic region within which at least two magnetic states can be imposed. Upon magnetoresistive electrical interaction with the device, the relative orientation of the magnetic states of the changeable magnetic region, and a proximate reference magnetic region, can be sensed thereby providing a binary data storage capability. The present invention limits the electrical interaction to only a preferred portion of the changeable magnetic region, e. g. , the portion within which the two magnetic states can be dependably predicted to be substantially uniform, and opposite of one another. Structures for limiting the electrical interaction to this preferred portion of the changeable magnetic region are disclosed, and include smaller interaction regions, and alternating areas of insulation and conductive, interaction regions, disposed proximate the changeable magnetic region. The principles of the present invention can be applied to magnetic random access memory (âMRAMâ) arrays, which employ giant magnetoresistive (âGMRâ) cells, or magnetic tunnel junction (âMTJâ) cells, at the intersections of bitlines and wordlines, and also to magnetic sensors such as magnetic data storage devices having access elements used to access data on a magnetic data storage medium.

US Patent:

7492631, Feb 17, 2009

Filed:

May 9, 2008

Appl. No.:

12/118496

Inventors:

Solomon Assefa - Ossining NY, US
William J. Gallagher - Ardsley NY, US
Chung H. Lam - Peekskill NY, US
Jonathan Z. Sun - Shrub Oak NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11C 11/14

US Classification:

365171, 365158, 365173

Abstract:

An exemplary method for resetting a spin-transfer based random access memory system, the method comprising, inducing a first current through a conductor, wherein the first current is operative to change a direction of orientation of a magnetic reference layer, inducing a second current from the drain terminal to the write terminal via a conductive layer, wherein the second current is operative to change the direction of a magnetic state of a free layer magnet, and inducing a third current through the conductor, wherein the third current is operative to change the direction of magnetic orientation of the reference layer.

US Patent:

7505308, Mar 17, 2009

Filed:

May 9, 2008

Appl. No.:

12/118441

Inventors:

Solomon Assefa - Ossining NY, US
William J. Gallagher - Ardsley NY, US
Chung H. Lam - Peekskill NY, US
Jonathan Z. Sun - Shrub Oak NY, US

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11C 11/14
G11C 11/15
G11C 11/16

US Classification:

365158, 365171, 365173, 3652255, 257414, 257421

Abstract:

An exemplary magnetic random access memory system comprising, a spin-current generating portion including, a ferromagnetic film layer, and a conductance layer, a first write portion in electrical contact with the ferromagnetic film including, a selection device, and a first read portion in electrical contact with the conductance layer including, a free layer magnet, a read non-magnetic layer, and a reference layer, a second write portion in electrical contact with the ferromagnetic film, and a second read portion in electrical contact with the conductance layer.

US Patent:

60727187, Jun 6, 2000

Filed:

Feb 10, 1998

Appl. No.:

9/021342

Inventors:

David William Abraham - Ossining NY
William Joseph Gallagher - Ardsley NY
Philip Louis Trouilloud - Mahwah NJ

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11C 1115

US Classification:

365173

Abstract:

Magnetic memory devices are disclosed having multiple magnetic tunnel junctions therein writable together into an average state. For example, a magnetic random access memory ("MRAM") array is disclosed having respective pluralities of crossing first and second electrically conductive lines forming a plurality of intersecting regions across the array. The array includes a plurality of magnetic memory cells, each disposed at a respective one of the plurality of intersecting regions. Each cell includes at least two magnetic tunnel junctions therein, writable together into an average state, according to electrical and resultant magnetic stimuli applied thereto via a respective first and second conductive line. The at least two magnetic tunnel junctions provided in each magnetic memory cell provide a predictable magnetic response for all cells across the array. Only the cell at an intersecting region selected by stimuli applied via each of the first and second electrically conductive lines forming the selected region is written, and other cells along the first and second electrically conductive lines forming the selected region are not written.

US Patent:

61046337, Aug 15, 2000

Filed:

Feb 10, 1998

Appl. No.:

9/021515

Inventors:

David William Abraham - Ossining NY
William Joseph Gallagher - Ardsley NY
Philip Louis Trouilloud - Mahwah NY

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G11C 1114

US Classification:

365171

Abstract:

Magnetic memory cells include a changeable magnetic region with a magnetic axis along which two directions of magnetization can be imposed, thereby providing two respective states into which the cells are changeable according to electrical and resultant magnetic stimuli applied thereto. Asymmetry in the magnetic stimuli applied to the cell while writing a state therein is disclosed to provide a predictable magnetization pattern evolution from the first direction to the second direction. Physical asymmetry in the layout and/or magnetization of the cell is also disclosed which provides the predictable pattern evolution. These principles can be applied to magnetic random access memory (MRAM) arrays which employ magnetic tunnel junction (MTJ) cells at the intersections of bitlines and wordlines which supply the electrical and resultant magnetic stimuli to write the cells therein.