Abstract: A high-frequency oscillation element has a ferromagnetic material which exhibits thermal fluctuation of magnetization and generates spin fluctuations in conduction electrons, a nonmagnetic conductive material which is laminated on the first magnetic material and transfers the conduction electrons, a magnetic material which is laminated on the nonmagnetic conductive material, generates magnetic resonance upon injection of the conduction electrons, and imparts magnetic dipole interaction to magnetization of a neighboring magnetic area by means of magnetic vibration stemming from the magnetic resonance, a first electrode electrically coupled with the first magnetic material, and a second electrode electrically coupled with the second magnetic material.

Abstract: A magnetic recording and reproducing apparatus includes a magnetic head that has a spin-torque oscillator and a magnetic disk and the spin-torque oscillator detects a magnetic field from the magnetic disk and outputs a signal. A criterion used to determine the rotational speed of the magnetic disk, the frequency shift of the spin-torque oscillator produced by a magnetic field from the magnetic disk, a characteristic oscillation frequency of the spin-torque oscillator and the full-width at half maximum of an oscillation spectrum is given in order for a read signal output from the spin-torque oscillator to satisfy a desired signal-to-noise ratio and a magnetic recording and reproducing apparatus is configured based on the criterion.

Abstract: A magnetic head, includes a magnetic oscillation element, the oscillation frequency of which is modulated by a medium magnetic field, and a reproducing device configured to detect a phase difference between the adjacent oscillation signals derived from the magnetic oscillation element and output a phase difference signal as a reproduced signal.

Abstract: A magnetic head, includes a magnetic oscillation element, the oscillation frequency of which is modulated by a medium magnetic field, and a reproducing device configured to detect a phase difference between the adjacent oscillation signals derived from the magnetic oscillation element and output a phase difference signal as a reproduced signal.

Abstract: A spin-tunnel transistor having a tunnel barrier layer formed of an antiferromagnetic material which is exchange coupled with a first or second ferromagnetic metal layer of a base B formed adjoining to the antiferromagnetic material, so as to fix magnetization of the adjoining ferromagnetic layer. The base B includes a nonmagnetic metal layer which is formed between the first and second ferromagnetic metal layers and decouple magnetization coupling between the first and second ferromagnetic metal layers. The base B is formed between a collector and an emitter to form tri-terminal device. Those spin-tunnel transistor may be used as a sensor of a magnetic reproducing head used in a hard disk drive.

Abstract: A magnetic recording head includes a spin wave oscillator having a lamination film including a first magnetic layer and a second magnetic layer, and a pair of electrodes adapted to inject a current between the first magnetic layer and the second magnetic layer to generate a spin wave in one of the first magnetic layer and the second magnetic layer; and a recording magnetic pole provided on one side with the spin wave oscillator, the spin wave oscillator locally heating the recording track prior to recording by the recording magnetic pole.

Abstract: A magnetic memory device includes a magnetic tunnel junction element having a plurality of ferromagnetic layers stacked with a dielectric layer interposed between the adjacent ferromagnetic layers and storing magnetic information through reversal of magnetization of at least one of the magnetization layers, and a spin wave oscillator having a magnetization free layer, a nonmagnetic layer stacked on the magnetization free layer, a magnetization pinned layer stacked on the nonmagnetic layer, and a pair of electrodes adapted to apply current in the direction perpendicular to the surface of the magnetization free layer, the nonmagnetic layer and the magnetization pinned layer to thereby generate a spin wave. The spin wave oscillator is arranged in vicinity of the magnetic tunnel junction element to allow heating of the magnetic tunnel junction element and reversal of magnetization.

Abstract: A magnetic sensor includes a magnetic oscillation element whose oscillation frequency changes depending on the magnitude of an external magnetic field, and an oscillation element provided in the vicinity of the magnetic oscillation element and oscillating at an oscillation frequency close to that of the magnetic oscillation element. The magnetic oscillation element includes a first fixed magnetization layer whose magnetization is fixed, a first magnetization oscillation layer, a first non-magnetic layer provided between the first fixed magnetization layer and the first magnetization oscillation layer, and a pair of electrodes for passing current perpendicularly to the film surfaces of the first fixed magnetization layer, the first magnetization oscillation layer, and the first non-magnetic layer. These two elements are used in combination with the passed current to acquire a high frequency oscillation signal generated from the magnetic oscillation element and the oscillation element.

Abstract: In a spin-torque oscillator, a first ferromagnetic layer, a non-magnetic layer and a second ferromagnetic layer are stacked. A pair of electrodes perpendicularly applies a current onto each plane of the first ferromagnetic layer, the non-magnetic layer and the second ferromagnetic layer. The current induces a precession of a magnetization of at least one of the first ferromagnetic layer and the second ferromagnetic layer. The at least one is formed by an in-plane magnetization film having a uniaxial magnetic anisotropy. A magnetic field generator generates a magnetic field to control a direction of the magnetization so that a non-linearity frequency shift of the precession by the uniaxial magnetic anisotropy cancels a non-linearity frequency shift of the precession by a demagnetizing field on the in-plane magnetization film.

Abstract: A magnetic recording and reproducing apparatus includes a magnetic head that has a spin-torque oscillator and a magnetic disk and the spin-torque oscillator detects a magnetic field from the magnetic disk and outputs a signal. A criterion used to determine the rotational speed of the magnetic disk, the frequency shift of the spin-torque oscillator produced by a magnetic field from the magnetic disk, a characteristic oscillation frequency of the spin-torque oscillator and the full-width at half maximum of an oscillation spectrum is given in order for a read signal output from the spin-torque oscillator to satisfy a desired signal-to-noise ratio and a magnetic recording and reproducing apparatus is configured based on the criterion.

Abstract: A magnetic element has a first magnetic material exhibiting thermal fluctuation of magnetization which depends on an external magnetic field and generates spin fluctuation in conduction electrons; a nonmagnetic conductive material which is laminated on the first magnetic material and transfers the conduction electrons; a second magnetic material which is laminated on the nonmagnetic conductive material and generates a magnetic resonance upon injection of the conduction electrons; a first electrode electrically coupled with the first magnetic material; and a second electrode electrically coupled with the second magnetic material.

Abstract: It is made possible to to provide a spin-torque oscillator that has a high Q value and a high output. A spin-torque oscillator includes: an oscillating field generating unit configured to generate an oscillating field; and a magnetoresistive element including a magnetoresistive effect film including a first magnetization pinned layer of which a magnetization direction is pinned, a first magnetization free layer of which a magnetization direction oscillates with the oscillating field, and a first spacer layer interposed between the first magnetization pinned layer and the first magnetization free layer.

Abstract: A magnetic sensor includes a magnetoresistance element having a peak of a thermal fluctuation strength of magnetization under a magnetic field having a certain frequency, a frequency filter connected to the magnetoresistance element and having its transmittance decreased or increased in substantially the frequency of the magnetic field to output a signal corresponding substantially to the peak of the thermal fluctuation strength of magnetization, and a detector connected to the frequency filter to detect the magnetic field based on the signal of the frequency filter.

Abstract: A magnetic sensor includes a magnetoresistance element having a peak of a thermal fluctuation strength of magnetization under a magnetic field having a certain frequency, a frequency filter connected to the magnetoresistance element and having its transmittance decreased or increased in substantially the frequency of the magnetic field to output a signal corresponding substantially to the peak of the thermal fluctuation strength of magnetization, and a detector connected to the frequency filter to detect the magnetic field based on the signal of the frequency filter.

Abstract: A magnetic head, includes a magnetic oscillation element, the oscillation frequency of which is modulated by a medium magnetic field, and a reproducing device configured to detect a phase difference between the adjacent oscillation signals derived from the magnetic oscillation element and output a phase difference signal as a reproduced signal.

Abstract: A magnetic sensor includes a magnetoresistance element having a peak of a thermal fluctuation strength of magnetization under a magnetic field having a certain frequency, a frequency filter connected to the magnetoresistance element and having its transmittance decreased or increased in substantially the frequency of the magnetic field to output a signal corresponding substantially to the peak of the thermal fluctuation strength of magnetization, and a detector connected to the frequency filter to detect the magnetic field based on the signal of the frequency filter.

Abstract: A magnetic sensor includes a magnetic oscillation element whose oscillation frequency changes depending on the magnitude of an external magnetic field, and an oscillation element provided in the vicinity of the magnetic oscillation element and oscillating at an oscillation frequency close to that of the magnetic oscillation element. The magnetic oscillation element includes a first fixed magnetization layer whose magnetization is fixed, a first magnetization oscillation layer, a first non-magnetic layer provided between the first fixed magnetization layer and the first magnetization oscillation layer, and a pair of electrodes for passing current perpendicularly to the film surfaces of the first fixed magnetization layer, the first magnetization oscillation layer, and the first non-magnetic layer. These two elements are used in combination with the passed current to acquire a high frequency oscillation signal generated from the magnetic oscillation element and the oscillation element.

Abstract: A magnetic oscillation element includes: a magnetization fixing layer whose magnetization direction is substantially pinned toward one direction; a nonmagnetic layer that is disposed on the magnetization fixing layer; a magnetization free layer whose magnetization direction fluctuates, the magnetization free layer being disposed on the nonmagnetic layer; and a pair of electrodes that applies a current in a direction perpendicular to the film surface of the magnetization fixing layer, the nonmagnetic layer, and the magnetization free layer, wherein the magnetization free layer is excited with a magnetization vibration caused by spin transfer from the magnetization fixing layer due to the appliance of the current.

Abstract: Some spin tunnel transistors with a larger current transmittance and a higher MR ratio are described. One of the spin tunnel transistor comprises a collector; an emitter; abase formed between the collector and the emitter, including a first ferromagnetic metal layer variable in its magnetization under an external magnetic field; a barrier layer formed between the first ferromagnetic metal layer and one of the collector and the emitter, the other of the collector and the emitter including a semiconductor crystal layer; and a transition metal silicide crystal layer between the semiconductor crystal layer and the base. The transition metal silicide crystal layer may be replaced with a palladium layer, a transition metal nitride layer, or a transition metal carbide layer.

Abstract: Some spin tunnel transistors with a larger current transmittance and a higher MR ratio are described. One of the spin tunnel transistor comprises a collector; an emitter; abase formed between the collector and the emitter, including a first ferromagnetic metal layer variable in its magnetization under an external magnetic field; a barrier layer formed between the first ferromagnetic metal layer and one of the collector and the emitter, the other of the collector and the emitter including a semiconductor crystal layer; and a transition metal silicide crystal layer between the semiconductor crystal layer and the base. The transition metal silicide crystal layer may be replaced with a palladium layer, a transition metal nitride layer, or a transition metal carbide layer.