307 results about "Giant magnetoresistance" patented technology

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 reader of a magnetoresistive head includes a granular type free layer. The magnetoresistive head is for a current-perpendicular to plane type, and can be used in either a giant magnetoresistance (GMR) or ballistic magnetoresistance (BMR) scheme. The granular type free layer includes an insulating matrix, for example but not by way of limitation, Al2O3, and metal magnetic grains, for example but not by way of limitation, Ni, CoFe or NiFe. The metal grain size is about 10 to 30 nm, and the effect of having these grains interspersed in the insulative matrix is to provide a softer granular type free layer having a low magnetization. Accordingly, the granular type free layer of the present invention can be made thicker, on the order of about 5 to 10 nm, thus further improving overall thermal stability, reducing spin transfer effect and improving output read signal.

A spin-torque oscillator (STO) has a single free ferromagnetic layer that forms part of both a giant magnetoresistance (GMR) structure with a nonmagnetic conductive spacer layer and a tunneling magnetoresistance (TMR) structure with a tunnel barrier layer. The STO has three electrical terminals that connect to electrical circuitry that provides a spin-torque excitation current through the conductive spacer layer and a lesser sense current through the tunnel barrier layer. When the STO is used as a magnetic field sensor, the excitation current causes the magnetization of the free layer to oscillate at a fixed base frequency in the absence of an external magnetic field. A detector coupled to the sense current detects shifts in the free layer magnetization oscillation frequency from the base frequency in response to external magnetic fields.

A “scissoring-type” current-perpendicular-to-the-plane giant magnetoresistive (CPP-GMR) sensor has magnetically damped free layers. In one embodiment each of the two free layers is in contact with a damping layer that comprises Pt or Pd, or a lanthanoid (an element selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Th, Yb, and Lu). Each of the two free layers has one of its surfaces in contact with the sensor's electrically conducting nonmagnetic spacer layer and its other surface in contact with its associated damping layer. A nonmagnetic film may be located between each free layer and its associated damping layer. In another embodiment the damping element is present as a dopant or impurity in each of the two free layers. In another embodiment a nanolayer of the damping element is located within each of the two free layers.

The invention relates to an integrated coil-biased giant magnetoresistance magneto-dependent sensor. A traditional magneto-dependent sensor has a complex manufacturing process, low finished product rate of products and low sensing sensitivity. The integrated coil-biased giant magnetoresistance magneto-dependent sensor comprises a whetatone bridge consisting of four GMR (Giant Magnetoresistance) magneto-dependent resistors, an integrated soft magnetic material layer and an integrated bias coil, wherein the integrated soft magnetic material layer is of an annular structure; a pair of clearances is formed in the diameter direction of the integrated soft magnetic material layer; a pair of resistors at opposite positions on a whetatone bridge arm is placed in one clearance of the integrated soft magnetic material layer; another pair of resistors at the opposite positions on the whetatone bridge arm is placed in the other clearance of the integrated soft magnetic material layer; and the width of the pair of clearances is consistent. The integrated bias coil is encircled on the integrated soft magnetic material layer. The integrated coil biased giant magnetoresistance magneto-dependent sensor has the advantages of small size of the sensor, high sensitivity and favorable linearity.

Spin-torque devices are based on a combination of giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR) effects. The basic structure has various applications, including amplifiers, oscillators, and diodes. For example, if the low-magnetoresistance contact is biased below a critical value, the device may function as a microwave-frequency selective amplifier. If the low-magnetoresistance contact is biased above the critical value, the device may function as a microwave oscillator. A plurality of low- and high-magnetoresistance contact pairs may be induced to oscillate in a phase-locked regime, thereby multiplying output power. The frequency of operation of these devices will be tunable by the external magnetic field, as well as by the direct bias current, in the frequency range between 10 and 100 GHz. The devices do not use semiconductor materials and are expected to be exceptionally radiation-hard, thereby finding application in military nanoelectronics.

The invention discloses a monolithic reference full bridge magnetic field sensor. The magnetic field sensor is a Wheatstone bridge formed by a magneto-resistor reference element and a sensing element. Both a sensing arm and a reference arm are magnetic tunnel junction resistance or giant magnetoresistance material. According to the invention, the sensitivity of the sensing element and the reference element are adjusted through one or one set of magnetic bias combination, exchange bias, magnetic shielding or shape anisotropy performance. In addition, bridge output offset and symmetry can be optimized through presetting and adjusting a resistance value ratio of the reference element to the sensing element. Through using the technology, the magnetic field sensor presents excellent temperature stability, low offset voltage and excellent voltage symmetry.

A method for making a current-perpendicular-to the-plane giant magnetoresistance (CPP-GMR) sensor with a Heusler alloy pinned layer on the sensor's Mn-containing antiferromagnetic pinning layer uses two annealing steps. A layer of a crystalline non-Heusler alloy ferromagnetic material, like Co or CoFe, is deposited on the antiferromagnetic pinning layer and a layer of an amorphous X-containing ferromagnetic alloy, like a CoFeBTa layer, is deposited on the Co or CoFe crystalline layer. After a first in-situ annealing of the amorphous X-containing ferromagnetic alloy, the Heusler alloy pinned layer is deposited on the amorphous X-containing ferromagnetic layer and a second high-temperature annealing step is performed to improve the microstructure of the Heusler alloy pinned layer.

An apparatus according to one embodiment includes a magnetic head having multiple magnetic transducers, the transducers including read sensors. The read sensors are of at least two differing types selected from a group consisting of tunneling magnetoresistance (TMR), giant magnetoresistance (GMR), anisotropic magnetoresistance (AMR), and inductive sensors.

High-frequency resonance method is used to measure magnetic parameters of magnetic thin film stacks that show magnetoresistance including MTJs and giant magnetoresistance spin valves. The thin film sample can be unpatterned. Probe tips are electrically connected to the surface of the film (or alternatively one probe tip can be punched into the thin film stack) and voltage measurements are taken while injecting high frequency oscillating current between them to cause a change in electrical resistance when one of the layers in the magnetic film stack changes direction. A measured resonance curve can be determined from voltages at different current frequencies. The damping, related to the width of the resonance curve peak, is determined through curve fitting. In embodiments of the invention a variable magnetic field is also applied to vary the resonance frequency and extract the magnetic anisotropy and / or magnetic saturation of the magnetic layers.

A method, apparatus, and article of manufacture for a current-perpendicular-to-plane (CPP) giant magnetoresistance (GMR) or a tunneling magnetoresistance (TMR) read sensor is proposed. The CPP read sensor comprises an amorphous ferromagnetic first seed layer, a polycrystalline nonmagnetic second seed layer, a nonmagnetic first cap layer, a nonmagnetic second cap layer, and a ferromagnetic third gap layer. A read gap is defined by a distance between the ferromagnetic first seed layer and the ferromagnetic third cap layer.

The CPPGMR element of the present invention has an orientation layer 12 formed on a substrate 11 to texture a Heusler alloy into a (100) direction, an underlying layer 13 that is an electrode for magneto-resistance measurement stacked on the orientation layer 12, a lower ferromagnetic layer 14 and an upper ferromagnetic layer 16 each stacked on the underlying layer 13 and made of a Heusler alloy, a spacer layer 15 sandwiched between the lower ferromagnetic layers 14 and the upper ferromagnetic layers 16, and a cap layer 17 stacked on the upper ferromagnetic layer 16 for surface-protection. This manner makes it possible to provide, inexpensively, an element using a current-perpendicular-to-plane giant magneto-resistance effect (CPPGMR) of a thin film having a trilayered structure of a ferromagnetic metal / a nonmagnetic metal / a ferromagnetic metal, thereby showing excellent performances.

A spin-torque oscillator (STO) has a single free ferromagnetic layer that forms part of both a giant magnetoresistance (GMR) structure with a nonmagnetic conductive spacer layer and a tunneling magnetoresistance (TMR) structure with a tunnel barrier layer. The STO has three electrical terminals that connect to electrical circuitry that provides a spin-torque excitation current through the conductive spacer layer and a lesser sense current through the tunnel barrier layer. When the STO is used as a magnetic field sensor, the excitation current causes the magnetization of the free layer to oscillate at a fixed base frequency in the absence of an external magnetic field. A detector coupled to the sense current detects shifts in the free layer magnetization oscillation frequency from the base frequency in response to external magnetic fields.

The invention discloses a mining steel wire rope online detection device and a mining steel wire rope online detection method based on a giant magnetoresistance sensor array. The device comprises a probe, a signal conditioning module, a data acquisition card, a computer and a positioning module. The method comprises the following steps: magnetizing the steel wire rope by using an excitation device in the probe, and detecting a leakage magnetic field generated by damage by using a giant magnetoresistance sensor in the probe; processing an output signal of the probe by using the signal conditioning module, and inputting the processed output signal into the computer together with a signal of the positioning module through the data acquisition card; displaying the probe signal in real time on the computer, and comparing the probe signal with a preset threshold value to determine whether damage exists on the steel wire rope to be detected; if the probe signal is higher than the preset threshold value, indicating that damage exists on the steel wire rope to be detected, further determining the type and size of the damage, and determining a damage position according to the signal of the positioning module. The detection device and the detection method have the outstanding characteristics that by adopting the probe consisting of the giant magnetoresistance sensor array, the sensitivity of the detection device can be increased remarkably. The device and the method have good application prospects in damage detection of the mining steel wire rope.

A three-dimensional circuit and methods for fabricating such a circuit are described. The three-dimensional circuit includes a plurality of stacked levels on a substrate. Each level includes a plurality of all-metal circuit components exhibiting giant magnetoresistance and arranged in two dimensions, the circuit further includes an interconnect for providing interconnections between the circuit components on different ones of the plurality of levels.

The invention discloses a multi-layered thickness eddy current testing device based on a giant magnetoresistance sensor and an intelligent algorithm. The device generates actuating signals via a signal generator, and provides the actuating signals for built-in GMR and drive coil of magnetic steel after the signals are amplified by a power amplifier. The device detects the magnitude of the eddy current signals based on the built-in GMR and the drive coil of the magnetic steel, and the signals are sent to an amplifying circuit for being amplified after being tested by a detection circuit. The output of the amplifying circuit is collected to a computer by a data acquisition circuit based on a single chip microcomputer to be processed. The signal has a close relation with the thickness of the detected multi-layered conducting materials, carries out back calculation after adopting an improved BP network and can obtain the thickness of the conducting materials of each layer. The device is applicable to the thickness testing of multi-layered conducting structure in fields of machine, printed circuit board, aerospace, national defense and the like.

A magnetic sensing device for use in a magnetic head includes a sensor stack structure having a sensing layer structure and an insulator structure formed adjacent the sensing layer structure. The insulator structure includes a plurality of oxidized metallic sublayers, a plurality of nitrided metallic sublayers, or a plurality of oxynitrided metallic sublayers. The insulator structure may be a capping layer structure of a giant magnetoresistance sensor or, alternatively, a tunnel barrier layer structure of a tunneling magnetoresistance sensor or a magnetic random access memory. Advantageously, each treated metallic sublayer is sufficiently uniformly treated so as to increase the magnetoresistive effect and improve soft magnetic properties of the magnetic sensing device. A method for use in forming the magnetic sensing device of the present application includes the steps of forming a sensor stack structure which includes a sensing layer structure; depositing a metallic layer; performing, on the metallic layer, either an oxidation, nitridation, or oxynitridation process; and repeating the steps of depositing and performing one or more times to thereby form an insulator structure.

This invention discloses a magnetic sensor and manufacturing method thereof. The magnetic sensor includes a plurality of giant magnetoresistance components, each of which includes a free layer, a conductive layer and a fixing layer orderly laminated on the substrate, wherein the fixing layer is formed by orderly laminating a first magnetic layer, a Ru layer, a second magnetic layer and an anti-ferromagnetic layer; a magnetizing heat treatment is carried out to fix the magnetizing direction of the fixing layer. The thickness magnetic moments of the first and second magnetic layers are different from each other; the thickness of the Ru layer is in the range of four to ten. The magnetocaloric treatment is carried out to maintain a anti-parallel state between the first and second magnetic layers. A giant magnetoresistance component is formed by using a plane surface and the others are formed by using corresponding slope on the substrate so as to detect a magnetic field along three axial directions. According to this invention, it is easily to control the magnetizing direction of the fixing layer in the heat treatment.

The invention discloses a tri-axial accelerometer with giant magneto-resistance effect. The tri-axial accelerometer comprises a bonding substrate, giant magneto-sensitive resistors and micro accelerators, wherein the giant magneto-sensitive resistors are arranged on the upper surface of the bonding substrate, and are in positional correspondence to giant magneto-sensitive resistors on the upper surface of a sensitive mass block of the accelerator in each detection direction; the micro-accelerators are arranged above the bonding substrate and are connected with the bonding substrate; and each of the micro-accelerators comprises the sensitive mass block, a ferromagnetic thin film and a cantilever beam. According to the tri-axial micro-mechanical accelerator disclosed by the invention, an overall structural design is adopted, and three accelerators for detection in different directions are integrally manufactured on the same frame, therefore, the tri-axial accelerometer is reasonable in structure, simple in detection circuit, convenient to use, good in reliability and suitable for microminiaturization.

The invention belongs to the technical field of nondestructive test, and relates to a defect identification and evaluation method of a metallic conductor based on a giant magnetoresistance sensor. A detection probe adopted by the method comprises an exciting coil, the giant magnetoresistance sensor and a permanent magnet, wherein the giant magnetoresistance sensor is fixed at the bottom of the exciting coil; and the permanent magnet is fixed at the outer side of the exciting coil. The method comprises the steps of placing the detection probe at the surface of a tested piece; exerting a sine signal on the exciting coil; moving the detection probe to scan the tested piece; demodulating an output signal of the giant magnetoresistance sensor to obtain amplitude and phase angle information; recording the position of the detection probe in the scanning process; respectively drawing a curve of the amplitude changing along with the position of the probe and a curve of the phase angle changing along with the position of the probe; judging that whether a defect exists at the scanning position; and evaluating the position and the size of the defect. The defect identification and evaluation method of the metallic conductor has the advantages of being easy to operate, high in response speed, good in instantaneity, accurate in judging and evaluating at the same time, easy to carry out and the like.

Transceiver components for a transmission line are described. A driver includes a first network of thin-film elements exhibiting giant magnetoresistance, and a first input conductor inductively coupled to at least one of the thin-film elements in the first network. At least one dimension of each thin-film element in the first network is configured with reference to the characteristic impedance of the transmission line. A receiver includes a second network of thin-film elements exhibiting giant magnetoresistance, and a second input conductor inductively coupled to at least one of the thin-film elements in the second network. A termination impedance in series with the second input conductor has a value relating to the characteristic impedance of the transmission line.

The invention discloses a micro acceleration transducer based on a silicon substrate giant magnetoresistance effect, which mainly comprises a bonding substrate, an iron magnetic membrane and an acceleration sensitive body, wherein the iron magnetic membrane is arranged in a rectangular groove (that is, a bottom groove) in the bonding substrate; the acceleration sensitive body is arranged above the bonding substrate and is connected with the bonding substrate; and the acceleration sensitive body comprises a sensitive mass correspondingly arranged above the bottom groove, a giant magnetic-sensing resistor arranged on the upper surface of the sensitive mass and corresponding to the iron magnetic membrane in position, a cantilever arranged around the sensitive mass, and a support frame body arranged on the outer side of the cantilever. The giant magnetic-sensing resistor layer vibrates in the direction perpendicular to the upper surface of the iron magnetic membrane and along with the sensitive mass. The micro acceleration transducer adopts an integral structure design, is reasonable in structure, simple in detection circuit, convenient to use, good in reliability, and suitable for miniaturization.

The invention relates to devices for measuring currents, in particular to a giant magnetoresistance effect current sensor with a magnetic shielding shell and a bias coil. The giant magnetoresistance effect current sensor comprises the U-shaped magnetic shielding shell, a giant magnetoresistance chip, a bias coil winding, a current-carrying conductor, a PCB, a bias current source and a signal processing circuit, wherein the probe of the giant magnetoresistance effect current sensor is formed by the U-shaped magnetic shielding shell, the giant magnetoresistance chip, the bias coil winding, the current-carrying conductor and the PCB, the signal processing circuit comprises a bias magnetic field generating circuit, a giant magnetoresistance chip supply voltage switching circuit, a reference voltage generating circuit and an improved difference operational amplification circuit, the magnetic shielding shell overcomes the defect that magnetic fields are prone to being simultaneously influenced by an outside stray magnetic field due to the high sensitivity of giant magnetoresistance on the magnetic fields, and meanwhile hysteresis errors are reduced and alternate and direct currents are precisely measured through the method of providing the bias coil winding for a bias magnetic field.

A nonvolatile sequential machine is described which includes a semiconductor controller operable to control operation of the nonvolatile sequential machine according to a state machine comprising a plurality of states. The nonvolatile sequential machine further includes a plurality of state registers operable to store the plurality of states. The state registers comprise nonvolatile random-access memory operation of which is based on giant magnetoresistance.

The invention relates to a perpendicular magnetic anisotropic multi-layered film, which comprises a substrate, a bottom layer, a lower magnetic layer, a middle layer, an upper magnetic layer and a covering layer, wherein at least one of the lower magnetic layer and the upper magnetic layer is a composite magnetic layer which consists of a main layer and a transitional layer, the main layer is made of perpendicular magnetic anisotropic material, and the transitional layer is made of magnetic metal material with spin polarization higher than the spin polarization of the perpendicular magnetic anisotropic material, and is positioned between the main layer and the middle layer. When the middle layer is a barrier layer, the composite magnetic layer also can be made of metal material with a spin diffusion length larger than 3nm. Under the premise of guaranteeing excellent perpendicular magnetic anisotropy, the invention can enhance the magnetoresistance property, reduce mutual magnetostatic reaction and decrease the reverse field or reverse current of a corresponding device. The invention is applicable to giant magnetoresistance devices or tunneling magnetoresistance devices, such as magnetic sensors, magnetic random-access memorys and magnetic logic devices.

The invention relates to a giant magnetoresistance effect based sensor for measuring directions and intensity of magnetic fields, belonging to the technical field of magnetic field measurement. The sensor comprises an X sensing unit for measuring the magnetic field component in the X direction and a Y sensing unit for measuring the magnetic field component in the Y direction, wherein each sensing unit adopts two-stage bridge structure; the first stage bridges adopt the same constant-voltage power source for supplying power; the second stage bridges adopt the output voltage of the first stage bridges for supplying power; the first stage output bridges output the voltage generated by the measured magnetic fields; and the second stage bridges output the voltage which is the square number with the voltage generated by the measured magnetic fields. The sensor is suitable for measuring the intensity and directions of the unknown magnetic fields, can be applied to measuring such magnetic fields as geomagnetic fields, magnetic fields in the transmission lines and the substations and the like, can be used for measuring the current in the power systems and the electronic systems, has small volume, high response speed and high sensitivity and greatly improves the measuring frequency range and response speed of the sensor.

The invention relates to a giant magnetoresistance array current sensor comprising a giant magnetoresistance chip sub-board array (1), an annular mother PCB (printed circuit board) (2), an eight-channel amplifier circuit (3), an eight-channel sampling retaining and A / D (analog to digital) conversion circuit (4) and a FPGA (field programmable gate array) signal processing circuit (5). The giant magnetoresistance chip sub-board array (1) comprises a giant magnetoresistance chip AA005-02 and two strip-shaped aluminum-nickel-cobalt permanent magnets, wherein the aluminum-nickel-cobalt permanent magnets are arranged on two ends of the giant magnetoresistance chip AA005-02, and the magnetizing direction of the strip-shaped aluminum-nickel-cobalt permanent magnets is consistent with the magnet-sensing direction of the giant magnetoresistance chip AA005-02; eight giant magnetoresistance chip sub-boards are arranged on the annular mother PCB (2); the voltage signals outputted by the giant magnetoresistance chip AA005-02 are inputted into the eight-channel amplifier circuit (3), and then the voltage signals are amplified and made to enter the eight-channel sampling retaining and A / D conversion circuit (4); and the simulated voltage signals are converted into digital signals, and then the eight-way digital signals are processed by the FPGA signal processing circuit (5).

A spin-injection magnetoresistance effect element that can avoid use of a large writing current and allows use of a large reading current. The spin-injection magnetoresistance effect element includes layers that may exhibit a tunnel magnetoresistance effect and layers that may exhibit a giant magnetoresistance effect.