Abstract: A magnetic recording and reproducing apparatus for recording and reproducing bit information comprising a magnetic head having a spin torque oscillator configured to readout bit information which is recorded on a magnetic recording medium, a detector configured to detect amplitude of a first signal, the first signal which is to reproduce the bit information, and a controller configured to control the magnetic head so as to read the bit information recorded on the magnetic recording medium when the amplitude of the first signal detected by the detector is smaller than a predetermined value.

Abstract: According to one embodiment, an oscillator includes first to third conductive bodies, a first stacked unit, and a magnetic unit. The first conductive body includes first, second region, and third regions. The second conductive body includes a portion separated from the third region. The first stacked unit is provided between the third region and the portion. The first stacked unit includes first to fourth magnetic layers, and first to third intermediate layers. At least a portion of the magnetic unit and at least a portion of the first stacked unit overlap each other. In a first state, the first to fourth magnetizations are aligned with a third direction perpendicular to the first direction and the second direction. The second magnetization has a component in a reverse orientation of the first magnetization. The fourth magnetization has a component in a reverse orientation of the third magnetization.

Abstract: A magnetic recording and reproducing apparatus for recording and reproducing bit information comprising a magnetic head having a spin torque oscillator configured to readout bit information which is recorded on a magnetic recording medium, a detector configured to detect amplitude of a first signal, the first signal which is to reproduce the bit information, and a controller configured to control the magnetic head so as to read the bit information recorded on the magnetic recording medium when the amplitude of the first signal detected by the detector is smaller than a predetermined value.

Abstract: According to an embodiment, a computing apparatus includes spin torque oscillators, an interaction unit, a variable direct-current supply device, and a measuring unit. The interaction unit controls an interaction between the spin torque oscillators. The variable direct-current supply device supplies a current to induce oscillations of the spin torque oscillators. The measuring unit measures AC signals obtained from the spin torque oscillators.

Abstract: According to one embodiment, a magnetic recording and reproducing device includes a magnetic recording medium, a magnetic head, and a controller. The controller implements a first operation and a second operation. The first operation is implemented in a first information recording interval including a first recording interval and a first non-recording interval. The second operation is implemented in a second information recording interval including a second recording interval and a second non-recording interval. The first operation includes in the first recording interval, generating a first signal magnetic field from the magnetic head, and in the first non-recording interval, generating a first non-signal magnetic field from the magnetic head. The second operation includes in the second recording interval, generating a second signal magnetic field from the magnetic head, and in the second non-recording interval, generating a second non-signal magnetic field from the magnetic head.

Abstract: According to one embodiment, a magnetic recording apparatus includes a spin-torque oscillator, a recording unit, and a controller. The spin-torque oscillator includes an oscillation layer. The recording unit includes at least one recording layer. Magnetization reversal in each recording layer is performed by excitation of cooperative dynamics between magnetization of the oscillation layer and magnetization of the recording layer. The controller controls precession of the magnetization of the oscillation layer, which is induced by application of an electric current to the spin-torque oscillator.

Abstract: According to one embodiment, a magnetic recording medium includes a first magnetic layer and a second magnetic layer. An easy magnetization axis of the first magnetic layer is aligned with a first direction. The first direction is from the first magnetic layer toward the second magnetic layer. The second magnetic layer has magnetic anisotropy in a plane perpendicular to the first direction. A second magnetization of the second magnetic layer is reverse orientation of a first magnetization of the first magnetic layer.

Abstract: According to an embodiment, a machine learning apparatus includes an interlayer accelerator. The interlayer accelerator includes interlayer units that generate, based on (a) an input vector of a first layer included in a neural network that includes three or more layers and (b) a learning weight matrix of the first layer, an input vector of a second layer next to the first layer. Each of the interlayer units includes a coupled oscillator array. The coupled oscillator array includes oscillators that oscillate at frequencies corresponding to differences between elements of the input vector of the first layer and elements of a row vector that is one row of the learning weight matrix, and combines oscillated signals generated by the oscillators to obtain a calculated signal.

Abstract: According to an embodiment, a pattern matching device includes unit cells, a circuit, and a measuring unit. Each unit cell includes a first magnetization reversal element used to store input data and including a first magnetic layer in which a direction of magnetization is variable, a second magnetization reversal element used to store template data and including a second magnetic layer in which a direction of magnetization is variable, and a spin-torque oscillator provided therebetween. The circuit applies a current to a selected spin-torque oscillator to acquire a high frequency signal from the selected spin-torque oscillator. The measuring unit measures a degree of matching between the input data and the template data based on the high frequency signal.

Abstract: According to an embodiment, a magnetic recording head includes a main magnetic pole and a spin torque oscillator. The spin torque oscillator includes a first perpendicular free layer, a second perpendicular free layer, and a first spacer layer, each of the first perpendicular free layer and the second perpendicular free layer including a magnetic anisotropy axis in a direction perpendicular to a film plane of the spin torque oscillator. An effective perpendicular magnetic anisotropy magnetic field of the first perpendicular free layer is smaller than an effective perpendicular magnetic anisotropy magnetic field of the second perpendicular free layer, and a current is applied from the first perpendicular free layer side to the second perpendicular free layer side.

Abstract: According to an embodiment, a pattern matching device includes unit cells, a circuit, and a measuring unit. Each unit cell includes a first magnetization reversal element used to store input data and including a first magnetic layer in which a direction of magnetization is variable, a second magnetization reversal element used to store template data and including a second magnetic layer in which a direction of magnetization is variable, and a spin-torque oscillator provided therebetween. The circuit applies a current to a selected spin-torque oscillator to acquire a high frequency signal from the selected spin-torque oscillator. The measuring unit measures a degree of matching between the input data and the template data based on the high frequency signal.

Abstract: According to one embodiment, a magnetic recording apparatus includes a spin-torque oscillator, a recording unit, and a controller. The spin-torque oscillator includes an oscillation layer. The recording unit includes at least one recording layer. Magnetization reversal in each recording layer is performed by excitation of cooperative dynamics between magnetization of the oscillation layer and magnetization of the recording layer. The controller controls precession of the magnetization of the oscillation layer, which is induced by application of an electric current to the spin-torque oscillator.

Abstract: According to an embodiment, a magnetic recording head includes a main magnetic pole and a spin torque oscillator. The spin torque oscillator includes a first perpendicular free layer, a second perpendicular free layer, and a first spacer layer, each of the first perpendicular free layer and the second perpendicular free layer including a magnetic anisotropy axis in a direction perpendicular to a film plane of the spin torque oscillator. An effective perpendicular magnetic anisotropy magnetic field of the first perpendicular free layer is smaller than an effective perpendicular magnetic anisotropy magnetic field of the second perpendicular free layer, and a current is applied from the first perpendicular free layer side to the second perpendicular free layer side.

Abstract: According to an embodiment, a magnetic recording apparatus includes following elements. The spin torque oscillator generates a first oscillating magnetic field. The recording medium unit includes one or more recording medium layers which are stacked, each of the one or more recording medium layers including a recording medium and spin-wave lines each of which generates a second oscillating magnetic field. The write magnetic field source generates a write magnetic field. The controller is configured to control the spin torque oscillator, the spin-wave lines, and the write magnetic field source to simultaneously apply the write magnetic field, and the first and second oscillating magnetic fields to target medium magnetization in the recording medium.

Abstract: According to an embodiment, a magnetic recording and reproducing apparatus includes a recording medium and a reproducing head. The recording medium includes a concentric circular plurality of tracks. The reproducing head includes a spin torque oscillator and reproduces information from the recording medium using the spin torque oscillator, the spin torque oscillator including an oscillation layer with a first cross-track direction width, a polarizer layer with a second cross-track direction width, and a spacer layer provided between the oscillation layer and the polarizer layer. The first cross-track direction width is larger than double the second cross-track direction width, and the second cross-track direction width is smaller than an inter-track distance.

Abstract: According to one embodiment, a three-dimensional magnetic recording and reproducing apparatus includes a magnetic head and a magnetic storage medium. The magnetic head includes a spin-torque oscillator including a free layer, a non-magnetic layer and a fixed layer, magnetization of the free layer being rotatable, the non-magnetic layer being laminated on the free layer, the fixed layer being laminated on the non-magnetic layer, a magnetization direction of the fixed layer being fixed. The magnetic storage medium includes first magnetic layers formed of magnetic materials having different resonant frequencies, each of the first magnetic layers being formed of an in-plane magnetization film and having recording tracks.

Abstract: According to an embodiment, a magnetic recording apparatus includes following elements. The spin torque oscillator generates a first oscillating magnetic field. The recording medium unit includes one or more recording medium layers which are stacked, each of the one or more recording medium layers including a recording medium and spin-wave lines each of which generates a second oscillating magnetic field. The write magnetic field source generates a write magnetic field. The controller is configured to control the spin torque oscillator, the spin-wave lines, and the write magnetic field source to simultaneously apply the write magnetic field, and the first and second oscillating magnetic fields to target medium magnetization in the recording medium.

Abstract: According to one embodiment, a magnetic oscillator includes a layered film and a pair of electrodes. The layered film includes a first ferromagnetic layer, an insulating layer stacked on the first ferromagnetic layer, and a second ferromagnetic layer stacked on the insulating layer. The pair of electrodes is configured to apply a current to the layered film in a direction perpendicular to a film surface of the layered film. Regions having different resistance area products are provided between the first ferromagnetic layer and the second ferromagnetic layer.

Abstract: According to one embodiment, a spin-torque oscillator includes a non-magnetic unit, one or more first magnetic unit, and a second magnetic unit. The non-magnetic unit is formed of a non-magnetic body. The one or more first magnetic unit is connected to the non-magnetic unit and generates a pure spin current indicating the flow of the electron spin that does not accompany an electric charge current. The second magnetic unit is connected to the non-magnetic unit in a manner such that a distance between the second magnetic unit and the first magnetic unit is shorter than a spin diffusion length indicating a distance that an electronic spin polarization is maintained in the non-magnetic unit. The second magnetic unit oscillates by the pure spin current.

Abstract: According to an embodiment, a magnetic recording and reproducing apparatus includes a recording medium and a reproducing head. The recording medium includes a concentric circular plurality of tracks. The reproducing head includes a spin torque oscillator and reproduces information from the recording medium using the spin torque oscillator, the spin torque oscillator including an oscillation layer with a first cross-track direction width, a polarizer layer with a second cross-track direction width, and a spacer layer provided between the oscillation layer and the polarizer layer. The first cross-track direction width is larger than double the second cross-track direction width, and the second cross-track direction width is smaller than an inter-track distance.