International Business Machines Corporation

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Infineon Technologies Ag

John Casimir Slonczewski

Jonathan Zanhong Sun

Bernell E Argyle

William Joseph Gallagher

Bruce David Terris

Stuart Stephen Papworth Parkin

Rolf Allenspach

Bojan Petek

David William Abraham

Lubomyr Taras Romankiw

Richard Joseph Gambino

Philip Louis Trouilloud

Daniel A Nepela

Sol Krongelb

Hin P Lee

Dean A Herman, Jr

Thomas J Beaulieu

Thomas C Arnoldussen

Thomas Penney, Iii

Pieter Dekker

Stuart Stephen Parkin

Stuart P Parkin

Philip Edward Batson

Rainer Leuschner

Otto Voegeli

Michael Hatzakis

Stuart S P Parkin

Kam Leung Lee

Joachim Gerhard Clabes

George J Fan

Bertram A Calhoun

A spin-current switched magnetic memory element includes a plurality of magnetic layers, at least one of the plurality of magnetic layers having a perpendicular magnetic anisotropy component and including a current-switchable magnetic moment, and at least one barrier layer formed adjacent to the plurality of magnetic layers. The plurality of magnetic layers includes at least one composite layer.

Spin-current switched magnetic memory element suitable for circuit integration and method of fabricating the memory element

A method of fabricating a spin-current switched magnetic memory element includes providing a wafer having a bottom electrode, forming a plurality of layers, such that interfaces between the plurality of layers are formed in situ, in which the plurality of layers includes a plurality of magnetic layers, at least one of the plurality of magnetic layers having a perpendicular magnetic anisotropy component and including a current-switchable magnetic moment, and at least one barrier layer formed adjacent to the plurality of magnetic layers, lithographically defining a pillar structure from the plurality of layers, and forming a top electrode on the pillar structure.

A structure includes an electrically conductive material possessing spontaneous magnetization ('free magnet') not in contact with an electrically resistive material possessing spontaneous magnetization ('pinned magnet'), and a spacer having free electrons to transfer spin between the electrically resistive material and the electrically conductive material. During operation, an existing direction of magnetization of the free magnet is changed to a new direction of magnetization, by a spin current generated by transfer of heat between at least the spacer and the pinned magnet. Thereafter, the new direction of magnetization of the free magnet is sensed. Many such structures are fabricated to have an easy axis of magnetic anisotropy in the free magnet, to implement memories that write data by transferring heat. Several such structures are fabricated to have an easy plane of magnetic anisotropy in the free magnet, to implement oscillators that generate an oscillating signal, on transfer of heat.

Creating spin-transfer torque in oscillators and memories

A magnetic memory element switchable by current injection includes a plurality of magnetic layers, at least one of the plurality of magnetic layers having a perpendicular magnetic anisotropy component and including a current-switchable magnetic moment, and at least one barrier layer formed adjacent to the plurality of magnetic layers (e.g., between two of the magnetic layers). The memory element has the switching threshold current and device impedance suitable for integration with complementary metal oxide semiconductor (CMOS) integrated circuits.

A conductor with improved magnetic field per current ratio is disclosed. The conductor includes a magnetic liner lining a second surface and sides thereof. The corners of the conductor where the second surface and the sides meet are rounded. The rounded corners have been found to improve the concentration of magnetic flux in the magnetic liner.

Magnetically lined conductors

A magnetoresistive sensor includes a substrate and a layer of ferromagnetic material formed over the substrate. A plurality of nonmagnetic regions is formed within the layer of ferromagnetic material. Magnetic flux paths form around each one of the plurality of nonmagnetic regions when the layers of ferromagnetic material is not in a magnetic field. The flux paths are contained completely with the layer of ferromagnetic material and do not penetrate into the plurality of nonmagnetic regions. The sensor also provides for detecting a change in resistance through the layer of ferromagnetic material as a function of a magnetic field applied to the layer of ferromagnetic material.

Magnetoresistive sensor with magnetic flux paths surrounding non-magnetic regions of ferromagnetic material layer

A magnetic field sensor is described incorporating a plurality of magnetic stripes spaced apart on the surface of a substrate such that the stray magnetic fields at the ends of the magnetic stripes are magnetostatically coupled and the magnetic stripes are magnetized respectively in alternating directions, nonmagnetic conductive material positioned in the spaces between the magnetic stripes and electrodes for passing current crosswise through the plurality of magnetic stripes to detect a change in resistance by the giant magnetoresistive effect (MGR). The invention overcomes the problem of detecting low magnetic fields since the magnetic fields required to saturate magnetic stripes depends on the magnetostatic coupling which in turn can be controlled by the geometry and position of the magnetic stripes in the sensor.

Magnetoresistive sensor with magnetostatic coupling of magnetic regions

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 (&ldquo;MRAM&rdquo;) arrays, which employ giant magnetoresistive (&ldquo;GMR&rdquo;) cells, or magnetic tunnel junction (&ldquo;MTJ&rdquo;) 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.

Limiting magnetoresistive electrical interaction to a preferred portion of a magnetic region in magnetic devices

The use of ferrimagnetic materials is proposed for use in magnetic devices. Such magnetic devices include magnetic tunnel junctions (MTJ) which have at least two magnetic layers separated by an insulating barrier layer, wherein at least one of the two magnetic layers is ferrimagnetic. Such MTJ's are used in MRAM (magnetic random access memory) structures. Where the magnetic device is a magnetic sensor, it preferably includes a layer that comprises a ferrimagnetic material separated from another magnetic layer by a barrier layer and the magnetizations of the magnetic layer are oriented at an angle to one another.

Magnetic tunnel junctions using ferrimagnetic materials

A magnetic field sensor incorporates a plurality of magnetic stripes spaced apart on the surface of a substrate such that the stray magnetic fields at the ends of the magnetic stripes are magnetostatically coupled and the magnetic stripes are magnetized respectively in alternating directions, nonmagnetic conductive material positioned in the spaces between the magnetic stripes and electrodes for passing current crosswise through the plurality of magnetic stripes to detect a change in resistance by the giant magnetoresistive effect (MGR). The invention overcomes the problem of detecting low magnetic fields since the magnetic fields required to saturate magnetic stripes depends on the magnetostatic coupling which in turn can be controlled by the geometry and position of the magnetic stripes in the sensor.

Magnetoresistive sensor with magnetostatic coupling to obtain opposite alignment of magnetic regions

A magnetic tunnel junction (MTJ) device is usable as a magnetic field sensor or as a memory cell in a magnetic random access (MRAM) array. The MTJ device has a 'pinned' ferromagnetic layer whose magnetization is oriented in the plane of the layer but is fixed so as to not be able to rotate in the presence of an applied magnetic field in the range of interest, a 'free' ferromagnetic layer whose magnetization is able to be rotated in the plane of the layer relative to the fixed magnetization of the pinned ferromagnetic layer, and an insulating tunnel barrier layer located between and in contact with both ferromagnetic layers. The pinned ferromagnetic layer is formed as a sandwich of two antiferromagnetically coupled ferromagnetic layers separated by a metallic layer. The free and pinned ferromagnetic layers are located in separate spaced-apart planes so as to not overlap the tunnel barrier layer. An insulating layer surrounds the lateral perimeter of at least the free ferromagnetic layer and supports an electrical lead that makes contact with the free ferromagnetic layer.

Magnetic tunnel junction device with antiferromagnetically coupled

In the present invention, electrons flow through a free or excitable magnet, or reflect from it, to make its magnetization respond. To accomplish this, the spin vectors of the flowing electrons are preferentially polarized by an auxiliary ferromagnet, whose moment orientation is fixed. The electrons flow between the fixed and free ferromagnets through a non-magnetic metallic spacer which is thick enough to make the static inter-magnetic exchange coupling negligible. While transmitting thru or reflecting from the free ferromagnet, the spins of the moving electrons interact by quantum-mechanical exchange with the local, permanently present, spontaneously-polarized electron spins of the free magnet. This interaction causes a transfer of vectorial angular momentum between the several metallic layers in the device which causes the magnetization vector of the free magnet to change its direction continually with time. Thus excited, the magnetization vector will precess about its original axis. The precession cone angle will either attain a new equilibrium value which will be sustained by the current or will increase beyond 90.degree. and precess with decreasing amplitude until the magnetization vector has reversed by 180.degree. from its initial direction (i.e., switched).

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Katonah, NY, United States of America

John Casimir Slonczewski