International Business Machines Corporation

Stuart P Parkin

Luc Thomas

David William Abraham

William Joseph Gallagher

Philip Louis Trouilloud

John Casimir Slonczewski

Philip Edward Batson

Rai Moriya

Edward J Nowak

Daniel Christopher Worledge

Kota V R M Murali

Stephen L Brown

Timothy Phung

Aakash Pushp

A domain wall injector device uses electrical current passed across an interface between two magnetic regions whose magnetizations are aligned non-collinearly to create a domain wall or a series of domain walls in one of the magnetic regions. The method relies on a combination of innate fringing fields from the magnetic regions and the spin-transfer torque derived from the charge current. The device may be used to store data that are subsequently read out.

Domain wall injector device using fringing fields aided by spin transfer torque

Disclosed is a metal oxide semiconductor field effect transistor (MOSFET) having phase transition material incorporated into one or more components and an associated method. The MOSFET can comprise an asymmetric gate electrode having a phase transition material section (e.g., a chromium or titanium-doped vanadium dioxide (VO) section) above the drain-side of the channel region. Additionally or alternatively, the MOSFET can comprise source and drain contact landing pads comprising different phase transition materials (e.g., un-doped VOand chromium or titanium-doped VO, respectively). In any case, the phase transition material(s) are pre-selected so as to be insulative when the MOSFET is in the OFF state and the voltage difference between the drain region and the source region (V) is high in order to minimize leakage current and so as to be conductive when the MOSFET is in the ON state and Vis high in order to maintain drive current.

Field effect transistor having phase transition material incorporated into one or more components for reduced leakage current

A method and structure for depinning a domain wall that is in spatial confinement by a pinning potential to within a local region of a magnetic device. At least one current pulse applied to the domain has a pulse length sufficiently close to a precession period of the domain wall motion and the current pulses are separated by a pulse interval sufficiently close to the precession period such that: the at least one current pulse causes a depinning of the domain wall such that the domain wall escapes the spatial confinement; and each current pulse has an amplitude less than the minimum amplitude of a direct current that would cause the depinning if the direct current were applied to the domain wall instead of the at least one current pulse. The pulse length and pulse interval may be in a range of 25% to 75% of the precession period.

Sequence of current pulses for depinning magnetic domain walls

A method for use with a magnetic racetrack device includes placing domain walls having a first structure and domain walls having a second, different structure along the racetrack at stable positions corresponding to different regions within the device. The domain walls having the first structure and the domain walls having the second structure occupy alternating positions along the racetrack. A current pulse is applied to the racetrack, so that each of the domain walls moves to an adjacent region. This results in a transformation of the domain walls having the first structure into domain walls having the second structure, and vice versa. The first structure may be a vortex structure and the second structure may be a transverse structure.

Magnetic racetrack with current-controlled motion of domain walls within an undulating energy landscape

A racetrack memory device facilitates the manipulation of a series of domain walls along the racetrack. The racetrack is designed so that the domain wall energy increases and decreases in a continuous fashion between adjacent pinning sites, so that a domain wall does not become stuck between them. The variation in the domain wall energy along the racetrack can be provided by continuous variations of the racetrack's width (while maintaining constant thickness) and/or cross-sectional area (in which the racetrack dimensions are varied in both directions perpendicular to the length of the racetrack). Alternatively, this variation in domain wall energy may be provided by varying the magnetic properties of the racetrack along the racetrack while otherwise keeping the shape and size of the racetrack unchanged. In addition, variations of the racetrack's composition and/or shape can be used.

A semiconductor device formed between a wordline and a bitline comprises a growth layer, an antiferromagnetic layer formed on the growth layer, a pinned layer formed on the antiferromagnetic layer, a tunnel barrier layer formed on the pinned layer, and a free layer formed on the tunnel barrier. The wordline and bitline are arranged substantially orthogonal to one another. The growth layer, in turn, comprises tantalum and has a thickness greater than about 75 Angstroms. Moreover, the pinned layer comprises one or more pinned ferromagnetic sublayers. The tunnel barrier comprises magnesium oxide. Finally, the free layer comprises two or more free ferromagnetic sublayers, each free ferromagnetic sublayer having a magnetic anisotropy axis that is oriented about 45 degrees from the wordline and bitline. The semiconductor device may comprise, for example, a magnetic tunnel junction for use in magnetoresistive random access memory (MRAM) circuitry.

Magnetic tunnel junction with enhanced magnetic switching characteristics

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.

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San Jose, CA, United States of America

Stuart P Parkin