791 results about "Magnetic anisotropy" patented technology

A magnetic memory cell having a ferromagnetic free layer and a ferromagnetic pinned reference layer, each having an out-of-plane magnetic anisotropy and an out-of-plane magnetization orientation and switchable by spin torque. The cell includes a ferromagnetic assist layer proximate the free layer, the assist layer having a low magnetic anisotropy less than about 500 Oe. The assist layer may have in-plane or out-of-plane anisotropy.

A perpendicular magnetic recording medium comprising a substrate, a soft underlayer, a seed layer, a non-magnetic FCC NiW alloy underlayer, a non-magnetic HCP underlayer, and a magnetic layer. We have discovered that the combination of a seed layer comprising Ta and a NiW alloy underlayer uniquely improves media recording performance and thermal stability by achieving excellent coercivity of the thin bottom magnetic recording layer and narrow C axis orientation distribution.

A magnetoresistive element includes a first underlying layer having an NaCl structure and containing a nitride orienting in a (001) plane, a first magnetic layer provided on the first underlying layer, having magnetic anisotropy perpendicular to a film surface, having an L10 structure, and containing a ferromagnetic alloy orienting in a (001) plane, a first nonmagnetic layer provided on the first magnetic layer, and a second magnetic layer provided on the first nonmagnetic layer and having magnetic anisotropy perpendicular to a film surface.

A multi-state spin-torque transfer magnetic random access memory (STTMRAM) is formed on a film and includes a first magnetic tunneling junctions (MTJ) having a first fixed layer, a first sub-magnetic tunnel junction (sub-MTJ) layer and a first free layer. The first fixed layer and first free layer each have a first magnetic anisotropy. The STTMRAM further includes a non-magnetic spacing layer formed on top of the first MTJ layer and a second MTJ formed on top of the non-magnetic spacing layer. The second MTJ has a second fixed layer, a second sub-MTJ layer and a second free layer. The second fixed and second free layers each have a second magnetic anisotropy, wherein at least one of the first or second magnetic anisotropy is perpendicular to the plane of the film.

A magnetoresistive element includes a first reference layer having magnetic anisotropy perpendicular to a film surface, and an invariable magnetization, a recording layer having a stacked structure formed by alternately stacking magnetic layers and nonmagnetic layers, magnetic anisotropy perpendicular to a film surface, and a variable magnetization, and an intermediate layer provided between the first reference layer and the recording layer, and containing a nonmagnetic material. The magnetic layers include a first magnetic layer being in contact with the intermediate layer and a second magnetic layer being not in contact with the intermediate layer. The first magnetic layer contains an alloy containing cobalt (Co) and iron (Fe), and has a film thickness larger than that of the second magnetic layer.

A method of operating a magnetoresistive device is described. The device comprises a ferromagnetic region configured to exhibit magnetic anisotropy and to allow magnetisation thereof to be switched between at least first and second orientations and a gate capacitively coupled to the ferromagnetic region. The method comprises applying an electric field pulse to the ferromagnetic region so as to cause orientation of magnetic anisotropy to change for switching magnetisation between the first and second orientations.

The present invention to provide a new technique to reduce a variation in switching field of a magnetization free layer in a magnetic memory. The magnetic memory according to the present invention includes a magnetization free layer including a ferromagnetic layer having a shape magnetic anisotropy in a first direction and a magnetic strain constant is positive; and a stress inducing structure configured to apply a tensile stress to said magnetization free layer in a same direction as the first direction.

In a magnetic disk having a glass substrate, an amorphous underlayer is formed on the glass substrate. A magnetic layer is formed on the amorphous underlayer. The glass substrate is provided with a texture formed to induce magnetic anisotropy in the magnetic layer. The amorphous underlayer contains a group IVa element on a glass substrate side and a group Va element on a magnetic layer side.

Embodiments of the invention implement MEJs having improved read-write characteristics. In one embodiment, an MEJ includes: ferromagnetic fixed and free layers, a dielectric layer interposed between the ferromagnetic layers, and an additional dielectric layer proximate the free layer, where the fixed layer is magnetically polarized in a first direction, where the free layer has a first easy axis that is aligned with the first direction, and where the MEJ is configured such that when subject to a potential difference, the magnetic anisotropy of the free layer is altered such that the relative strength of the magnetic anisotropy along a second easy axis that is orthogonal to the first easy axis, compared to the strength of the magnetic anisotropy along the first easy axis, is magnified during the application of the potential difference, where the extent of the magnification is enhanced by the presence of the additional layer.

This magnetic multilayer device comprises, on a substrate, an alternating sequence of magnetic metallic layers M and oxide, hydride or nitride layers O. The number of layers M equals at least two. The layers M are continuous. There is interfacial magnetic anisotropy perpendicular to the plane of the layers at the level of the M / O interfaces.

In a magnetic disk having at least a glass substrate, a plurality of underlayers formed over the glass substrate, and a magnetic layer formed over the plurality of underlayers, at least one of the underlayers is an amorphous underlayer containing a VIa group element and carbon and, given that the remanent magnetization in a circumferential direction of the disk is Mrc and the remanent magnetization in a radial direction of the disk is Mrr, the magnetic disk has a magnetic anisotropy in which Mrc / Mrr being a ratio between Mrc and Mrr exceeds 1.

The reversible transverse susceptibility of magnetic nanoparticles is used to achieve magnetic flux amplification in magnetic resonance settings. Nanoparticles having substantially uniaxial or unidirectional magnetic anisotropy and a reversible transverse susceptibility in the presence of the high DC magnetic field provide either or both of an amplification of the generated signal of an inductive coil or the detected signal of an inductive coil.

A method of forming an MTJ memory cell and / or an array of such cells is provided wherein each such cell has a small circular horizontal cross-section of 1.0 microns or less in diameter and wherein the ferromagnetic free layer of each such cell has a magnetic anisotropy produced by a magnetic coupling with a thin antiferromagnetic layer that is formed on the free layer. The MTJ memory cell so provided is far less sensitive to shape irregularities and edge defects than cells of the prior art.

A magnetic tunnel transistor (MTT) having a pinned layer that has no antiferromagnetic material in an active area of the sensor. The MTT can include a layer of antiferromagnetic material that is exchange coupled with the pinned layer in an area outside of the active area of me sensor, such as outside the track-width, beyond the stripe height, or both outside the track-width and beyond the stripe height. The pinned layer can also be pinned without any exchange coupling at all. In that case, pinning can be assisted by shape enhanced magnetic anisotropy, by extending the pinned layer beyond the stripe height.

A method and system for providing a magnetic element are described. The magnetic element includes pinned and free layers, a nonmagnetic spacer layer between the free and pinned layers, and a stability structure. The free layer is between the spacer layer and the stability structure. The free layer has a free layer magnetization, at least one free layer easy axis, and at least one hard axis. The stability structure includes magnetic layers and is configured to decrease a first magnetic energy corresponding to the free layer magnetization being aligned with the at least one easy axis without decreasing a second magnetic energy corresponding to the free layer magnetization being aligned with the at least one hard axis. The magnetic element is configured to allow the free layer magnetization to be switched to between states when a write current is passed through the magnetic element.

A magnetic data track used in a magnetic shift register memory system may be fabricated by forming a multilayered stack of alternating dielectric and / or silicon layers. Vias of approximately 10 microns tall with a cross-section on the order of 100 nm×100 nm are etched in this multilayered stack of alternating layers. Vias may be etched form smooth or notched walls. Vias are filled by electroplating layers of alternating types of ferromagnetic or ferrimagnetic metals. The alternating ferromagnetic or ferrimagnetic layers are comprised of magnetic materials with different magnetization or magnetic exchange or magnetic anisotropies. These different magnetic characteristics allow the pinning of magnetic domain walls at the boundaries between these layers. Alternatively, vias are filled with a homogeneous ferromagnetic material. Magnetic domain walls are formed by the discontinuity in the ferromagnetic or ferromagnetic material that occurs at the notches or at the protuberances along the via walls.

A magnetic sensor comprising a bridge circuit in which four magnetoresistive devices are connected, the magnetoresistive device comprising a spin-valve, giant-magnetoresistive film comprising a pinned layer having unidirectional magnetic anisotropy, a free layer whose magnetization direction is rotated in alignment with an external magnetic field direction, and an intermediate layer sandwiched by the pinned layer and the free layer, and at least one of the magnetoresistive devices meeting the condition of 36°≦θ<45°, wherein θ is an acute angle between its longitudinal direction and the magnetization direction of the pinned layer.

A recording medium providing improved writeability in perpendicular recording applications includes a magnetic recording layer having an axis of magnetic anisotropy substantially perpendicular to the surface thereof, an exchange-spring layer ferromagnetically exchange coupled to the magnetic recording layer and having a coercivity less than the magnetic recording layer coercivity, and a coupling layer between the magnetic recording layer and the exchange-spring layer. The coupling layer regulates the ferromagnetic exchange coupling between the magnetic recording layer and the exchange-spring layer.

A magnetoresistive element includes a first reference layer having magnetic anisotropy perpendicular to a film surface, and an invariable magnetization, a recording layer having a stacked structure formed by alternately stacking magnetic layers and nonmagnetic layers, magnetic anisotropy perpendicular to a film surface, and a variable magnetization, and an intermediate layer provided between the first reference layer and the recording layer, and containing a nonmagnetic material. The magnetic layers include a first magnetic layer being in contact with the intermediate layer and a second magnetic layer being not in contact with the intermediate layer. The first magnetic layer contains an alloy containing cobalt (Co) and iron (Fe), and has a film thickness larger than that of the second magnetic layer.

A magnetoresistive effect element (1) has an arrangement in which a pair of ferromagnetic material layers (magnetization fixed layer (5) and magnetization free layer (7)) is opposed to each other through an intermediate layer (6) to obtain a magnetoresistive change by causing a current to flow in the direction perpendicular to the layer surface and in which the ferromagnetic material layers are annealed by anneal including rotating field anneal and the following static field anneal. A magnetic memory device comprises this magnetoresistive effect element (1) and bit lines and word lines sandwiching the magnetoresistive effect element (1) in the thickness direction. When the magnetoresistive effect element (1) and the magnetic memory device are manufactured, the ferromagnetic material layers (5, 7) are annealed by rotating field anneal and the following static field anneal. There are provided the magnetoresistive effect element that can obtain excellent magnetic characteristics by controlling magnetic anisotropies of the ferromagnetic material layers, the magnetic memory device including this magnetoresistive effect element and which may have excellent write characteristics, and methods for manufacturing these magnetoresistive effect element and magnetic memory device.

A magnetoresistive sensor having an MR stack biased by high anisotropy hard bias elements thereby reducing distortion in sensor operation and improving head to head operational values. The high anisotropy hard bias elements are formed from a hard magnetic material deposited in a thin film having a substantially axial preferred direction of magnetic anisotropy prior to application of a setting field. The magnetic anisotropy in the hard magnetic material is formed by oblique deposition in a direction approximately normal to the preferred direction of anisotropy in the resulting hard bias element.

The present invention provides a magnetization control method controlling, utilizing no current-induced magnetic field or spin transfer torque a magnetization direction with low power consumption, an information storage method, an information storage element, and a magnetic function element. The magnetization control method involves controlling a magnetization direction of a magnetic layer, and includes: forming a structure including (i) the magnetic layer which is an ultrathin film ferromagnetic layer having a film thickness of one or more atomic layers and of 2 nm or less, and (ii) an insulating layer provided on the ultrathin film ferromagnetic layer and working as a potential barrier; and controlling a magnetization direction of the ultrathin film ferromagnetic layer by applying either (i) a voltage to opposing electrodes sandwiching the structure and a base layer or (ii) an electric field to the structure to change magnetic anisotropy of the ultrathin film ferromagnetic layer. The magnetization control method further involves controlling a waveform of the applied voltage or the applied electric field to switch the magnetization direction.

A method of forming an MTJ memory cell and / or an array of such cells is provided wherein each such cell has a small circular horizontal cross-section of 1.0 microns or less in diameter and wherein the ferromagnetic free layer of each such cell has a magnetic anisotropy produced by a magnetic coupling with a thin antiferromagnetic layer that is formed on the free layer. The MTJ memory cell so provided is far less sensitive to shape irregularities and edge defects than cells of the prior art.

A magnetoresistive sensor having a magnetically stable free layer fabricated from a material having a positive magnetostriction such as a Co—Fe—B alloy. Although the free layer is fabricated from a material that has a positive magnetostriction, which would ordinarily make the free layer unstable, the magnetization of the free layer remains stable because of an induced magnetic anisotropy that has an easy axis of magnetization oriented parallel to the Air-bearing Surface (ABS). This magnetic anisotropy of the free layer is induced by an anisotropic texturing of the surface of the free layer. The resulting anisotropic surface texture is produced by an ion milling process that utilizes an ion beam directed at an acute angle relative to the normal to the surface of the wafer whereon the sensor is fabricated while the wafer is held on a stationary chuck. This angled, static ion milling produces an anisotropic surface texture, or roughness, of the free layer, which results in the above described magnetic anisotropy with an easy axis of magnetization in a desired orientation.

An MTJ MRAM cell element, whose free layer has a shape induced magnetic anisotropy, is formed between orthogonal word and bit lines. The bit line is a composite line which includes a high conductivity current carrying layer and a soft adjacent magnetic layer (SAL). During operation, the soft magnetic layer concentrates the magnetic field of the current and, due to its proximity to the free layer, it magnetically couples with the free layer to produce two magnetization states of greater and lesser stability. During switching, the layer is first placed in the less stable state by a word line current, so that a small bit line current can switch its magnetization direction. After switching, the state reverts to its more stable form as a result of magnetostatic interaction with the SAL, which prevents it from being accidentally rewritten when it is not actually selected and also provides stability against thermal agitation.

A perpendicular magnetic recording medium adapted for high recording density and high data recording rate comprises a non-magnetic substrate having at least one surface with a layer stack formed thereon, the layer stack including a perpendicular recording layer containing a plurality of columnar-shaped magnetic grains extending perpendicularly to the substrate surface for a length, with a first end distal the surface and a second end proximal the surface, wherein each of the magnetic grains has: (1) a gradient of perpendicular magnetic coercivity Hk extending along its length between the first end and second ends; and (2) predetermined local exchange coupling strengths along the length.

A motor includes: a stator (12) having coils; a rotor (11), which is disposed inside the stator and has a plurality of magnets; and a magnetic path switching part (18), which is provided in the rotor (11) and switches a magnetic path of the rotor (11) to select intense field control as a forward salient-pole structure or weak field control as an inverse salient-pole structure. The magnetic path switching part (18) is formed by use of a member having magnetic anisotropy, which is arranged on a magnetic path connecting magnets (13) of the same pole and a magnetic path connecting magnets (13) of different poles in the rotor (11). By changing the magnetic anisotropy of the member, the forward salient-pole structure and the inverse salient-pole structure are switched therebetween.

Semiconductor stack structures such as magnetic tunnel junction structures having a magnetic free layer that is grown on composite, obliquely deposited seed layers to induce an increased in-plane magnetic anisotropy Hk of the magnetic free layer. In one aspect, a semiconductor device includes a composite seed layer formed on a substrate, and a magnetic layer formed on the composite seed layer. The composite seed layer includes a first seed layer obliquely formed with an incident angle from a surface normal of the substrate along a first direction of the substrate, and a second seed layer obliquely formed with the incident angle on the first seed layer along a second direction of the substrate, opposite the first direction.

A magnetoresistance effect element includes: a magnetization free layer; a spacer layer provided adjacent to the magnetization free layer; a first magnetization fixed layer provided adjacent to the spacer layer on a side opposite to the magnetization free layer; and at least two second magnetization fixed layers provided adjacent to the magnetization free layer. The magnetization free layer, the first magnetization fixed layer, and the second magnetization free layers respectively have magnetization components in a direction substantially perpendicular to film surfaces thereof. The magnetization free layer includes: two magnetization fixed portions; and a domain wall motion portion arranged between the two magnetization fixed portions. Magnetizations of the two magnetization fixed portions constituting the magnetization free layer are fixed substantially antiparallel to each other in directions substantially perpendicular to the film surface. The domain wall motion portion is provided with magnetic anisotropy in a direction perpendicular to the film surface.