578 results about "Spin valve" patented technology

A method and system for providing a magnetic element and a corresponding memory are disclosed. In one aspect, the method and system include providing a dual spin tunnel/valve structure and at least one spin valve. The dual spin tunnel/valve structure includes a nonmagnetic spacer layer between a pinned layer and a free layer, another pinned layer and a barrier layer between the free layer and the other pinned layer. The free layers of the dual spin tunnel/valve structure and the spin valve are magnetostatically coupled. In one embodiment a separation layer resides between the dual spin tunnel/valve structure and the spin valve. In another aspect, the method and system include providing two dual spin valves, a spin tunneling junction there between and, in one embodiment, the separation layer. In both aspects, the magnetic element is configured to write to the free layers using spin transfer when a write current is passed through the magnetic element.

The present invention provides an improved top spin valve and method of fabrication. In the preferred embodiment of the top spin valve of the present invention, a seed layer is formed of non-magnetic material having the elements Ni and Cr. In the preferred embodiments, the seed layer material has an ion milling rate comparable to that of the free layer material. This allows free layer sidewalls to be formed with shorter tails, improving free layer-to-magnetic bias layer junction, thus improving free layer domain structure and track width. In one embodiment, the seed layer may have NiFeCr, with Cr from about 20% to 50%. In another embodiment, the seed layer may have NiCr, with about 40%. Some embodiments may have the seed layer formed on an optional Ta pre-seed layer. Such embodiments provide an improved fcc (111) texture particularly for NiFe and for NiFe/CoFe free layers grown on a seed layer improving spin valve performance, and especially in embodiments having very thin NiFe free layers, ultra thin NiFe free layers, and free layers without NiFe, such as a free layer of CoFe. Such a seed layer can improve AFM pinning layer texture to improve the exchange bias, thus providing better thermal stability. Such a seed layer also provides high resistivity and can improve the magnetostriction of adjacent NiFe free layer material or improve the soft properties of an adjacent CoFe free layer.

A magnetic element is disclosed wherein first and second interfaces of a free layer with a Hk enhancing layer and tunnel barrier, respectively, produce enhanced surface perpendicular anisotropy to lower switching current or increase thermal stability in a magnetic tunnel junction (MTJ). In a MTJ with a bottom spin valve configuration where the Hk enhancing layer is an oxide, the capping layer contacting the Hk enhancing layer is selected to have a free energy of oxide formation substantially greater than that of the oxide. The free layer may be a single layer or composite comprised of an Fe rich alloy such as Co₂₀Fe₆₀B₂₀. With a thin free layer, the interfacial perpendicular anisotropy may dominate the shape anisotropy to generate a magnetization perpendicular to the planes of the layers. The magnetic element may be part of a spintronic device or serve as a propagation medium in a domain wall motion device.

A method and system for providing and magnetic element is disclosed. In one aspect, the magnetic element includes at least a pinned layer, a free layer, and a current confined layer residing between the pinned layer and the free layer. The pinned layer is ferromagnetic and has a first magnetization. The current confined layer has at least one channel in an insulating matrix. The channel(s) are conductive and extend through the current confined layer. The free layer is ferromagnetic and has a second magnetization. The pinned layer, the free layer, and the current confined layer are configured to allow the magnetization of the free layer to be switched using spin transfer. The magnetic element may also include other layers, including layers for spin valve(s), spin tunneling junction(s), dual spin valve(s), dual spin tunneling junction(s), and dual spin valve/tunnel structure(s).

The present invention provides spin valve with a magnetic compensation field which couples to the pinned layer and counteracts sensing current induced magnetic field. The spin valve sensor of the present invention may be formed having a structure comprising: a free layer, a first spacer layer, a pinned layer, a pinning layer, a second spacer layer, and a compensation layer. The compensation layer may be formed of ferromagnetic material with its magnetization set so that the compensation field oriented in a reinforcing relationship with the magnetization of the pinned layer. Current through the compensation layer and the spacer layer may add to the compensation field. The spacer layer may be formed of a nonmagnetic material of sufficient thickness to prevent interaction between the pinning layer and the compensation layer while providing a sufficiently small distance to allow sufficient magnetic coupling to the pinned layer. The present invention may be used to improve thermal stability and reduce Barkhausen noise while not impacting output symmetry.

A method for maximizing the interfacial properties of magnetoresistive sensors, such as spin valve and GMR sensors used in storage devices, comprises selecting the materials for ferromagnetic layers and for electrically conductive spacers that are interposed between the ferromagnetic layers. The electronegativities of the selected materials are substantially matched so that an absolute value of the differences in electronegativities is minimized. The conductive spacer material provides a relatively low resistivity and a large mean free path. The sensors experience greater chemical and thermal stability, are corrosion resistant, and realize an increased signal output.

Magnetic nanoparticles and methods for their use in detecting biological molecules are disclosed. The magnetic nanoparticles can be attached to nucleic acid molecules, which are then captured by a complementary sequence attached to a detector, such as a spin valve detector or a magnetic tunnel junction detector. The detection of the bound magnetic nanoparticle can be achieved with high specificity and sensitivity.

A MTJ for a spintronic device is disclosed and includes a thin composite seed layer made of at least Ta and a metal layer having fcc(111) or hcp(001) texture as in Ta/Ti/Cu to enhance perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (CoFe/Ni)_X, (Co/NiFe)_X, (Co/NiCo)_X, (CoFe/NiFe)_X, or (CoFe/NiCo)_X composition where x is from 5 to 30. In one embodiment, a CPP-TMR spin valve has one or both of a laminated free layer and laminated reference layer with the aforementioned compositions. The MTJ includes an interfacial layer made of CoFeB, CoFeB/CoFe, or CoFe/CoFeB between each laminated structure and the tunnel barrier. The laminated layers are deposited by a low power and high Ar pressure process to avoid damaging interfaces between adjoining layers. Annealing occurs at 220° C. to 400° C. A laminated layer with high PMA may also be included in one or more layers of a spin transfer oscillator.

A method and apparatus of a spin-type magnetoresistance sensor having a free and pinned magnetic layer stacked with a non-magnetic interposed layer are disclosed. Specifically, the spin-valve type magnetoresistance sensor of the present invention is equipped with a free ferromagnetic layer, a pinned ferromagnetic layer, a non-magnetic spacer layer which is sandwiched between the aforementioned ferromagnetic layers, an anti-ferromagnetic layer which is disposed adjacent to the aforementioned pinned ferromagnetic layer and which is used to pin the direction of magnetization of said pinned ferromagnetic layer, a non-magnetic back layer which is disposed adjacent to the aforementioned free ferromagnetic layer and which is stacked on the opposite side the free ferromagnetic layer from the aforementioned nonmagnetic spacer layer, and an electron-reflective layer which is disposed adjacent to the aforementioned back layer and which is stacked on the opposite side of the back layer from the aforementioned free ferromagnetic layer.

A spin valve device includes a non-magnetic enhancement layer adjacent an ultra thin free layer. The thickness of the free layer may be less than the mean free path of a conduction electron through the free layer. The GMR ratio is significantly improved for free layer thicknesses below 50 Å. The enhancement layer allows electrons to travel longer in their spin state before encountering scattering sites. The electronic properties of the enhancement layer material can be matched with the adjacent free layer without creating a low resistance shunt path. Because the free layer may be made ultra thin and the enhancement layer is formed of a nonmagnetic material, less magnetic field is required to align the free layer, allowing for improved data density. Also, the enhancement layer allows for effective bias point control by shifting sensor current density distribution.

A high performance TMR sensor is fabricated by incorporating a tunnel barrier having a Mg/MgO/Mg configuration. The 4 to 14 Angstroms thick lower Mg layer and 2 to 8 Angstroms thick upper Mg layer are deposited by a DC sputtering method while the MgO layer is formed by a NOX process involving oxygen pressure from 0.1 mTorr to 1 Torr for 15 to 300 seconds. NOX time and pressure may be varied to achieve a MR ratio of at least 34% and a RA value of 2.1 ohm-um². The NOX process provides a more uniform MgO layer than sputtering methods. The second Mg layer is employed to prevent oxidation of an adjacent ferromagnetic layer. In a bottom spin valve configuration, a Ta/Ru seed layer, IrMn AFM layer, CoFe/Ru/CoFeB pinned layer, Mg/MgO/Mg barrier, CoFe/NiFe free layer, and a cap layer are sequentially formed on a bottom shield in a read head.

A spin valve magnetoresistance sensor of a thin film magnetic head. In one embodiment, a spin valve magnetoresistance sensor is provided with a spin valve film, in which a base layer including a first base film of Ta or some other nonmagnetic metal and, on top of this, a second base film of an alloy represented by NiFeX (where X is at least one element selected from among Cr, Nb, Rh) is formed on a substrate, and on top of this are formed by layering a free magnetic layer and pinned magnetic layer arranged to enclose a nonmagnetic conductive layer, as well as an antiferromagnetic layer, the second base film has an fcc (face-centered cubic) structure and also has a (111) orientation.

A method and system for providing a magnetic element are described. The method and system include providing a pinned layer, fabricating a metallic spacer layer and oxidizing a portion of the spacer layer in an environment including at least oxygen and a gas inert with respect to the spacer layer to provide an oxide layer. The method and system also include creating a free layer. The oxide layer is between a remaining metallic portion of the spacer layer and the free layer. In one aspect, the system includes a chamber and a gas diffusion apparatus within the chamber. The gas diffusion apparatus includes a plurality of nozzles and defines a plane. The gas exits each of the plurality of nozzles in a cone having an apex angle. The nozzles are directed at a nozzle tilt angle of at least half of the apex angle from the plane and the spacer layer.

The magnetic signal reproduction system comprises a magnetic recording medium comprising a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support and a reproduction head, wherein a number of protrusions equal to or greater than 10 nm in height on the magnetic layer surface, as measured by an atomic force microscope, ranges from 50 to 2500/10,000 μm², a quantity of lubricant on the magnetic layer surface, denoted as a surface lubricant index, ranges from 0.5 to 5.0, a surface abrasive occupancy of the magnetic layer ranges from 2 to 20 percent, the reproduction head is a magnetoresistive magnetic head comprising a spin-valve layer, the spin-valve layer comprises a magnetization free layer, a magnetization pinned layer and an antiferromagnetic layer, and the antiferromagnetic layer is comprised of alloy comprising iridium and manganese, and the reproduction head comes in sliding contact with the magnetic recording medium during signal reproduction.

A magnetoresistive element comprises an exchange coupling film having a under layer, an antiferromagnetic film and a ferromagnetic film, which are laminated in that order, the under layer including a metal having a face centered cubic crystal structure or hexagonal closest packing crystal structure which have a longer nearest neighbor atomic distance than that of the antiferromagnetic film. With this construction, it is possible to improve the exchange coupling field and to satisfy a stable output over a long period of time. A magnetoresistive element having a dual spin valve structure has a magnetization adjusting layer, which is antiferromagnetically connected to a pinned layer via an anti-parallel connection layer, to adjust the value of the product of the saturation magnetization of each of the magnetization adjusting layer and the pinned layer by the thickness thereof. Moreover, a magnetoresistance head use a giant magnetoresistance effect, and has at least one pair of pinned layer and free layer arranged via a non-magnetic spacer layer. The pinned layer has a pair of ferromagnetic layers which have different compositions and different coercive forces and which are antiferromagnetically connected to each other via a connection layer, so that the effective exchange coupling field of the pinned layer is 200 Oe or more.

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 magnetoresistive read head includes a spin valve having at least one free layer spaced apart from at least one pinned layer by a spacer. The free layer includes a thin CoFeOx lamination layer in the CoFe, and an optional Cu layer. The amount of oxygen is below 10% of total gas. The pinned layer is a single layer, or a synthetic multi-layered structure having a spacer between sub-layers, and may have the foregoing low-magnetostriction material. As a result, low magnetostriction is obtained to improve read quality and/or improve the pinned field of the pinned layer. Other parameters are not adversely affected.

A dual spin valve (SV) sensor is provided with a longitudinal bias stack sandwiched between a first SV stack and a second SV stack. The longitudinal bias stack comprises an antiferromagnetic (AFM) layer sandwiched between first and second ferromagnetic layers. The first and second SV stacks comprise antiparallel (AP)-pinned layers pinned by AFM layers made of an AFM material having a higher blocking temperature than the AFM material of the bias stack allowing the AP-pinned layers to be pinned in a transverse direction and the bias stack to be pinned in a longitudinal direction. The demagnetizing fields of the two AP-pinned layers cancel each other and the bias stack provides flux closures for the sense layers of the first and second SV stacks.

A nonmagnetic semiconductor device which may be utilized as a spin resonant tunnel diode (spin RTD) and spin transistor, in which low applied voltages and/or magnetic fields are used to control the characteristics of spin-polarized current flow. The nonmagnetic semiconductor device exploits the properties of bulk inversion asymmetry (BIA) in (110)-oriented quantum wells. The nonmagnetic semiconductor device may also be used as a nonmagnetic semiconductor spin valve and a magnetic field sensor. The spin transistor and spin valve may be applied to low-power and/or high-density and/or high-speed logic technologies. The magnetic field sensor may be applied to high-speed hard disk read heads. The spin RTD of the present invention would be useful for a plurality of semiconductor spintronic devices for spin injection and/or spin detection.

A magnetic field sensor structure including a first magnetoresistive element in a spin-valve arrangement with a first reference layer structure with a first reference magnetization direction and a second magnetoresistive element in a spin-valve arrangement with a second reference layer structure with a second reference magnetization direction, wherein the first and second magnetoresistive elements are arranged in a layer vertically above each other and galvanically isolated from each other by an intermediate layer, and wherein the first and second reference magnetization directions are different.

A CPP-GMR spin value sensor structure with an improved MR ratio and increased resistance is disclosed. All layers except certain pinned layers, copper spacers, and a Ta capping layer are oxygen doped by adding a partial O₂ pressure to the Ar sputtering gas during deposition. Oxygen doped CoFe free and pinned layers are made slightly thicker to offset a small decrease in magnetic moment caused by the oxygen dopant. Incorporating oxygen in the MnPt AFM layer enhances the exchange bias strength. An insertion layer such as a nano-oxide layer is included in one or more of the free, pinned, and spacer layers to increase interfacial scattering. The thickness of all layers except the copper spacer may be increased to enhance bulk scattering. A CPP-GMR single or dual spin valve of the present invention has up to a threefold increase in resistance and a 2 to 3% increase in MR ratio.

A CPP-GMR spin valve having a composite spacer layer comprised of at least one metal (M) layer and at least one semiconductor or semi-metal (S) layer is disclosed. The composite spacer may have a M/S, S/M, M/S/M, S/M/S, M/S/M/S/M, or a multilayer (M/S/M)_n configuration where n is an integer ≧1. The pinned layer preferably has an AP2/coupling/AP1 configuration wherein the AP2 portion is a FCC trilayer represented by Co_ZFe_(100-Z)/Fe_YCo_(100-Y)/Co_ZFe_(100-Z) where y is 0 to 60 atomic %, and z is 75 to 100 atomic %. In one embodiment, M is Cu with a thickness from 0.5 to 50 Angstroms and S is ZnO with a thickness of 1 to 50 Angstroms. The S layer may be doped with one or more elements. The dR/R ratio of the spin valve is increased to 10% or greater while maintaining acceptable EM and RA performance.

Current-perpendicular-to-plane (CPP) spin valve (SV) and magnetic tunnel junction (MTJ) sensors are provided having an antiparallel (AP)-coupled longitudinal bias stack for instack biasing to stabilize the free layer. A CPP sensor comprises a longitudinal bias stack adjacent to and in contact with a free (sense) layer of the sensor. The bias stack comprises an antiparallel (AP)-pinned layer including FM1 and FM2 layers separated by an antiparallel coupling (APC) layer. The FM1 layer is separated from the free layer of the sensor by a nonmagnetic spacer layer. By choosing the relative thicknesses of the FM1 and FM2 layers, the bias field HB from the AP-pinned layer and the ferromagnetic coupling field HFC between the FM1 layer and the free layer is made additive at the free layer for either positive or negative coupling. By ensuring that the bias field adds to the coupling field, the stability of the free layer by in-stack longitudinal biasing is improved.