417 results about "Spin polarization" patented technology

A magnetic switching device, includes a first electrode, a second electrode, and a nanoparticle having a magnetic moment and being disposed between the first and second electrodes. At least one of the first electrode and the second electrode includes a magnetic material which has a net spin polarization in its conduction band for injecting, into the nanoparticle, an electrical current including a net spin polarization for overcoming the magnetic moment of the nanoparticle upon selection of a predetermined magnitude for the electrical current.

A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, includes a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface, a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons, and a first nonmagnetic layer which is provided between the first pinned layer and the free layer. A saturation magnetization Ms of the free layer satisfies a relationship 0≧Ms<√{square root over ( )}{Jw / (6nAt)}. Jw is a write current density, t is a thickness of the free layer, A is a constant.

A spin valve structure for a spintronic device is disclosed and includes a composite seed layer made of at least Ta and a metal layer having a fcc(111) or hcp(001) texture to enhance perpendicular magnetic anisotropy (PMA) in an overlying (Co / Ni)x multilayer. The (Co / Ni)x multilayer is deposited by a low power and high Ar pressure process to avoid damaging Co / Ni interfaces and thereby preserving PMA. As a result, only a thin seed layer is required. PMA is maintained even after annealing at 220° C. for 10 hours. Examples of GMR and TMR spin valves are described and may be incorporated in spin transfer oscillators and spin transfer MRAMs. The free layer is preferably made of a FeCo alloy including at least one of Al, Ge, Si, Ga, B, C, Se, Sn, or a Heusler alloy, or a half Heusler alloy to provide high spin polarization and a low magnetic damping coefficient.

A magnetoresistive includes a first magnetic reference layer having a fixed magnetization direction, a magnetic free layer having a magnetization direction which is changeable by being supplied with spin polarized electrons, a second magnetic reference layer having a fixed magnetization direction, a first intermediate layer provided between the first magnetic reference layer and the magnetic free layer, and a second intermediate layer provided between the magnetic free layer and the second magnetic reference layer. The magnetic free layer and the first magnetic reference layer have directions of easy magnetization perpendicular or parallel to an in-plane direction. The first magnetic reference layer and the second magnetic reference layer have directions of easy magnetization perpendicular to each other.

A method and system for providing a magnetic element are disclosed. The method and system include providing first and second pinned layers, a free layer, and first and second barrier layers between the first and second pinned layers, respectively, and the free layer. The first barrier layer is preferably crystalline MgO, which is insulating, and configured to allow tunneling through the first barrier layer. Furthermore, the first barrier layer has an interface with another layer, such as the free layer or the first pinned layer. The interface has a structure that provides a high spin polarization of at least fifty percent and preferably over eighty percent. The second barrier layer is insulating and configured to allow tunneling through the second barrier layer. The magnetic element is configured to allow the free layer to be switched due to spin transfer when a write current is passed through the magnetic element.

A tunnel barrier in proximity with a layer of a rare earth element-transition metal (RE—TM) alloy forms a device that passes negatively spin-polarized current. The rare earth element includes at least one element selected from the group consisting of Gd, Tb, Dy, Ho, Er, Tm, and Yb. The RE and TM have respective sub-network moments such that the absolute magnitude of the RE sub-network moment is greater than the absolute magnitude of the TM sub-network moment. An additional layer of magnetic material may be used in combination with the tunnel barrier and the RE—TM alloy layer to form a magnetic tunnel junction. Still other layers of tunnel barrier and magnetic material may be used in combination with the foregoing to form a flux-closed double tunnel junction device.

A high speed and low power method to control and switch the magnetization direction and / or helicity of a magnetic region in a magnetic device for memory cells using spin polarized electrical current. The magnetic device comprises a reference magnetic layer with a fixed magnetic helicity and / or magnetization direction and a free magnetic layer with a changeable magnetic helicity. The fixed magnetic layer and the free magnetic layer are preferably separated by a non-magnetic layer, and the reference layer includes an easy axis perpendicular to the reference layer. A current can be applied to the device to induce a torque that alters the magnetic state of the device so that it can act as a magnetic memory for writing information. The resistance, which depends on the magnetic state of the device, is measured to thereby read out the information stored in the device.

A magnetoresistive sensor having a novel free layer and a method of producing the same are disclosed. The magnetoresistive sensor comprises a pinned layer, a barrier layer disposed over the pinned layer, and a free layer disposed over the barrier layer. The free layer comprises a first magnetic layer disposed over the barrier layer. The first magnetic layer has a positive spin polarization, a positive magnetostriction, and a polycrystalline structure. The free layer further comprises a second magnetic layer disposed over the first magnetic layer. The second magnetic layer has a negative magnetostriction and comprises at least cobalt (Co) and boron (B).

An MTJ in an MRAM array or in a TMR read head is comprised of a capping layer with a lower inter-diffusion barrier layer, an intermediate oxygen gettering layer, and an upper metal layer that contacts a top conductor. The composite capping layer is especially useful with a moderate spin polarization free layer such as a NiFe layer with a Fe content of about 17.5 to 20 atomic %. The capping layer preferably has a Ru / Ta / Ru configuration in which the lower Ru layer is about 10 to 30 Angstroms thick and the Ta layer is about 30 Angstroms thick. As a result, a high dR / R of about 40% is achieved with low magnetostriction less than about 1.0 E−6 in an MTJ in an MRAM array. Best results are obtained with an AlOx tunnel barrier layer formed by an in-situ ROX process on an 8 to 10 Angstrom thick Al layer.

A magnetoresistive element includes a free layer which contains a magnetic material and has an fct crystal structure with a (001) plane oriented, the free layer having a magnetization which is perpendicular to a film plane and has a direction to be changeable by spin-polarized electrons, a first nonmagnetic layer and a second nonmagnetic layer which sandwich the free layer and have one of a tetragonal crystal structure and a cubic crystal structure, and a fixed layer which is provided on only one side of the free layer and on a surface of the first nonmagnetic layer opposite to a surface with the free layer and contains a magnetic material, the fixed layer having a magnetization which is perpendicular to a film plane and has a fixed direction.

The addition of segmented write word lines to a spin-transfer MRAM structure serves to magnetically bias the free layer so that the precessional motion of the magnetization vector that is set in play by the flow of spin polarized electrons into the free layer allows said magnetic vector to be switched rather than to oscillate between two easy axis directions.

A magnetic device includes a magnetic reference layer with a fixed magnetization direction located either in the plane of the layer or perpendicular to the plane of the layer, a magnetic storage layer with a variable magnetization direction, a non-magnetic spacer separating the reference layer and the storage layer and a magnetic spin polarizing layer with a magnetization perpendicular to that of the reference layer, and located out of the plane of the spin polarizing layer if the magnetization of the reference layer is directed in the plane of the reference layer or in the plane of the spin polarizing layer if the magnetization of the reference layer is directed perpendicular to the plane of the reference layer. The spin transfer coefficient between the reference layer and the storage layer is higher than the spin transfer coefficient between the spin polarizing layer and the storage layer.

A magnetic shift register uses the inherent, natural properties of domain walls in magnetic materials to store data. The shift register uses spin electronics without changing the physical nature of its constituent materials. The shift register comprises a fine track or strip of magnetic materials. Information is stored as domain walls in the track. An electric current is applied to the track to move the magnetic moments along the track past a reading or writing device. In a magnetic material with domain walls, a current passed across the domain wall moves the domain wall in the direction of the current flow. As the current passes through a domain, it becomes “spin polarized”. When this spin polarized current passes through the next domain and across a domain wall, it develops a circle of spin torque. This spin torque moves the domain wall.

A new magnetic memory cell comprises a perpendicular-anisotropy tunneling magnetic junction (TMJ) and a fixed in-plane spin-polarizing layer, which is separated from the perpendicular-anisotropy data storage layer of tunneling magnetic junction by a non-magnetic layer. The non-magnetic layer can be made of metallic or dielectric materials.

A magnetic recording device includes: a laminated body including: a first ferromagnetic layer with a magnetization substantially fixed in a first direction; a second ferromagnetic layer with a variable magnetization direction; a first nonmagnetic layer disposed between the first ferromagnetic layer and the second ferromagnetic layer; and a third ferromagnetic layer with a variable magnetization direction. The magnetization direction of the second ferromagnetic layer is determinable in response to the orientation of a current, by allowing electrons spin-polarized by passing a current in a direction generally perpendicular to the film plane of the layers of the laminated body to act on the second ferromagnetic layer, and by allowing a magnetic field generated by precession of the magnetization of the third ferromagnetic layer to act on the second ferromagnetic layer.

Magnetic tunnel junction (“MTJ”) element structures and methods for fabricating MTJ element structures are provided. An MTJ element structure may comprise a crystalline pinned layer, an amorphous fixed layer, and a coupling layer disposed between the crystalline pinned layer and the amorphous fixed layer. The amorphous fixed layer is antiferromagnetically coupled to the crystalline pinned layer. The MTJ element further comprises a free layer and a tunnel barrier layer disposed between the amorphous fixed layer and the free layer. Another MTJ element structure may comprise a pinned layer, a fixed layer and a non-magnetic coupling layer disposed therebetween. A tunnel barrier layer is disposed between the fixed layer and a free layer. An interface layer is disposed adjacent the tunnel barrier layer and a layer of amorphous material. The first interface layer comprises a material having a spin polarization that is higher than that of the amorphous material.

The present invention generally relates to magnetic devices used in memory and information processing applications, such as giant magneto-resistance (GMR) devices and tunneling magneto-resistance devices. More specifically, the present invention is directed to a single ferromagnetic layer device in which an electrical current is used to control and change magnetic configurations as well as induce high frequency magnetization dynamics. The magnetic layer includes full spin-polarized magnetic material, which may also have non-uniform magnetization. The non-uniform magnetization is achieved by varying the shape or roughness of the magnetic material. The present invention may be used in memory cells, as well as high frequency electronics, such as compact microwave sources, detectors, mixers and phase shifters.

A magnetic memory is described. In one aspect, the magnetic memory includes magnetic junctions and at least one semi-spin valve (SSV) line adjacent to the magnetic junctions. Each magnetic junction includes a magnetic free layer. The SSV line(s) include a ferromagnetic layer and a nonmagnetic layer between the ferromagnetic layer and the magnetic junctions. The SSV line(s) are configured to exert a spin accumulation induced torque on at least a portion of the magnetic junctions due to an accumulation of spin polarized current carriers from a current that is substantially in-plane. The free layer is configured to be written using at least the spin accumulation induced torque. In another aspect, the magnetic memory includes magnetic memory cells and at least one spin torque (ST) line that is analogous to the SSV line. Each magnetic memory cell includes magnetic junction(s) analogous to those above and magnetoelectric selection device(s).

A probe structure for a scanning probe microscope comprises a nanowhisker (16,34) projecting from a free end of an upstanding tip member (4,26), and being formed integrally with the tip member. In another embodiment, a data storage medium comprises an array of nanowhiskers (54), each nanowhisker being formed from magnetic material, the diameter of the nanowhisker being such that a single ferromagnetic domain exists within the nanowhisker, preferably having a diameter not greater than about 25 nm and more preferably not greater than about 10 nm, and a read / write structure comprising the probe structure for injecting a stream of spin-polarised electrons into a selected nanowhisker of the array, either for sensing the direction of magnetisation in the nanowhisker, or for forcing the nanowhisker into a desired direction of magnetisation. When the probe nanowhisker is formed by a VLS process using a catalytic particle melt, the whisker may be formed with a sacrificial segment to allow for removal of the catalytic material by selective etching of the segment.

Magnetic tunnel junction (“MTJ”) element structures and methods for fabricating MTJ element structures are provided. An MTJ element structure may comprise a crystalline pinned layer, an amorphous fixed layer, and a coupling layer disposed between the crystalline pinned layer and the amorphous fixed layer. The amorphous fixed layer is antiferromagnetically coupled to the crystalline pinned layer. The MTJ element further comprises a free layer and a tunnel barrier layer disposed between the amorphous fixed layer and the free layer.Another MTJ element structure may comprise a pinned layer, a fixed layer and a non-magnetic coupling layer disposed therebetween. A tunnel barrier layer is disposed between the fixed layer and a free layer. An interface layer is disposed adjacent the tunnel barrier layer and a layer of amorphous material. The first interface layer comprises a material having a spin polarization that is higher than that of the amorphous material.

Stable magnetic field measurement is enabled without collapse of polarization or fluctuation of intensity of a laser beam incident on a glass cell of an optical pumping magnetic sensor. Excitation light generated with a light source, having optimized light intensity and polarized wave, through frequency stabilization, intensity control and polarized-wave control, is introduced via a polarized wave holding optical fiber to a magnetic sensor provided in a magnetic shield, and magnetic field measurement is performed by optical pumping using magneto-optical properties of spin-polarized alkali metal. The magnetic sensor has a structure where a lens, a polarization optical device, the glass cell and a photodetector, are integrally accommodated in a non-magnetic case.

A magnetoresistive element (and method of fabricating the magnetoresistive element) that includes a free ferromagnetic layer comprising a first reversible magnetization direction directed substantially perpendicular to a film surface, a pinned ferromagnetic layer comprising a second fixed magnetization direction directed substantially perpendicular to the film surface, and a nonmagnetic insulating tunnel barrier layer disposed between the free ferromagnetic layer and the pinned ferromagnetic layer, wherein the free ferromagnetic layer, the tunnel barrier layer, and the pinned ferromagnetic layer have a coherent body-centered cubic (bcc) structure with a (001) plane oriented, and a bidirectional spin-polarized current passing through the coherent structure in a direction perpendicular to the film surface reverses the magnetization direction of the free ferromagnetic layer.

A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, includes a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface, a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons, and a first nonmagnetic layer which is provided between the first pinned layer and the free layer. A saturation magnetization Ms of the free layer satisfies a relationship 0≧Ms<√{square root over ( )}{Jw / (6πAt)}. Jw is a write current density, t is a thickness of the free layer, A is a constant.

A magnetoresistive element includes a free layer which contains a magnetic material and has an fct crystal structure with a (001) plane oriented, the free layer having a magnetization which is perpendicular to a film plane and has a direction to be changeable by spin-polarized electrons, a first nonmagnetic layer and a second nonmagnetic layer which sandwich the free layer and have one of a tetragonal crystal structure and a cubic crystal structure, and a fixed layer which is provided on only one side of the free layer and on a surface of the first nonmagnetic layer opposite to a surface with the free layer and contains a magnetic material, the fixed layer having a magnetization which is perpendicular to a film plane and has a fixed direction.

Provided are a perpendicular magnetic tunnel junction (MTJ), a magnetic device including the same, and a method of manufacturing the MTJ, the perpendicular MTJ includes a lower magnetic layer; a tunnelling layer on the lower magnetic layer; and an upper magnetic layer on the tunnelling layer. One of the upper and lower magnetic layers includes a free magnetic layer that exhibits perpendicular magnetic anisotropy, wherein the magnetizing direction of the free magnetic layer is changed by a spin polarization current. A polarization enhancing layer (PEL) and an exchange blocking layer (EBL) are stacked between the tunnelling layer and the free magnetic layer.

An apparatus and method is discussed for characterizing a fluid sample downhole of aliphatic hydrocarbon compounds, aromatic hydrocarbon compound, or connate mud filtrates containing carbon-13 isotopes using an enhanced nuclear magnetic resonance (NMR) signal on a measurement-while-drilling device. To enhance the carbon-13 NMR signal these nuclei are being hyperpolarized. Either the Overhauser Effect (OE) or the Nuclear Overhauser Effect or optical pumping and the Spin Polarization Induced Nuclear Overhauser Effect (SPINOE) can serve as a mechanism for hyperpolarization of the carbon-13 nuclei.