Abstract: According to one embodiment, a magnetic head includes first and second magnetic poles, a conductive part, an element part, and first to fourth terminals. The conductive part is electrically insulated from the first and second magnetic poles. The first and second terminals are electrically connected to the conductive part. The element part is provided between the first and second magnetic poles and electrically connected to the first and second magnetic poles. The element part is conductive. The third terminal is electrically connected to the first magnetic pole. The fourth terminal is electrically connected to the second magnetic pole. A first magnetic pole temperature in a first state is higher than a second magnetic pole temperature of the second magnetic pole in the first state. A first current is supplied between the first and second terminals in the first state.

Abstract: According to one embodiment, a magnetic head includes first and second magnetic poles, and a stacked body provided between the first and second magnetic poles. The stacked body includes a first magnetic layer, a second magnetic layer provided between the second magnetic pole and the first magnetic layer, a third magnetic layer provided between the second magnetic pole and the second magnetic layer, a fourth magnetic layer provided between the second magnetic pole and the third magnetic layer, a first non-magnetic layer provided between the first magnetic layer and the first magnetic pole, a second non-magnetic layer provided between the second and first magnetic layers, a third non-magnetic layer provided between the third and second magnetic layers, a fourth non-magnetic layer provided between the fourth magnetic layer and the third magnetic layer, and a fifth non-magnetic layer provided between the second magnetic pole and the fourth magnetic layer.

Abstract: According to one embodiment, a magnetic recording device includes a magnetic head and a controller. The magnetic head includes first and second magnetic poles, a magnetic element provided between the first and second magnetic poles, and first and second terminals. The controller is configured to perform a recording operation. In the recording operation, the controller is configured to supply a recording current to the coil while applying an element voltage not less than a first voltage and not more than a second voltage between the first terminal and the second terminal. A differential resistance of the magnetic element when a positive applied voltage applied between the first terminal and the second terminal is changed while the recording current is supplied to the coil becomes a first peak when the applied voltage is the first voltage.

Abstract: According to one embodiment, a magnetic recording medium includes a first magnetic region, a second magnetic region, and a third magnetic region. The second magnetic region is provided between the third magnetic region and the first magnetic region in a first direction from the third magnetic region to the first magnetic region. A first composition ratio of a first Pt atomic concentration in the first magnetic region to a first Co atomic concentration in the first magnetic region is higher than a second composition ratio of a second Pt atomic concentration in the second magnetic region to a second Co atomic concentration in the second magnetic region. A third composition ratio of a third Pt atom concentration in the third magnetic region to a third Co atom concentration in the third magnetic region is higher than the second composition ratio.

Abstract: According to one embodiment, a magnetic head includes first and second magnetic poles, a conductive part, an element part, and first to fourth terminals. The conductive part is electrically insulated from the first and second magnetic poles. The first and second terminals are electrically connected to the conductive part. The element part is provided between the first and second magnetic poles and electrically connected to the first and second magnetic poles. The element part is conductive. The third terminal is electrically connected to the first magnetic pole. The fourth terminal is electrically connected to the second magnetic pole. A first magnetic pole temperature in a first state is higher than a second magnetic pole temperature of the second magnetic pole in the first state. A first current is supplied between the first and second terminals in the first state.

Abstract: According to one embodiment, a magnetic recording device includes a magnetic head and a controller. The magnetic head includes first and second magnetic poles, a magnetic element provided between the first magnetic pole and the second magnetic pole, first and second terminals electrically connected to one end and another end of the magnetic element, respectively, and a coil. The controller is electrically connected to the magnetic element and the coil, and performs a recording operation. In the recording operation, the controller supplies a recording current to the coil while applying an element voltage between the first and second terminals. When the applied voltage is changed while the recording current is supplied, a differential resistance of the magnetic element becomes a first differential resistance peak when the applied voltage is a first voltage, and becomes a second differential resistance peak when the applied voltage is a second voltage.

Abstract: According to one embodiment, a data processing device includes an acquisitor, and a processor. The acquisitor is configured to acquire a first acquired data and a first other data. The processor is configured to perform a first evaluation index derivation operation deriving a first evaluation index from a plurality of first regression labels and a plurality of first synthetic regression labels. The first regression labels are derived from a plurality of first machine learning models. The first machine learning models are derived from a plurality of first sample data. The first synthetic regression labels are derived from a plurality of first synthetic machine learning models. The first synthetic machine learning models are derived from the first sample data and the first acquire data by a first transfer leaning. The first sample data are derived from the first other data or a first conversion other data.

Abstract: According to one embodiment, a magnetic head includes a first magnetic pole, a second magnetic pole, and a stacked body. The first magnetic pole includes a first face and a second face crossing the first face. The second face includes a first face region continuous with the first face. The second magnetic pole includes a third face and a fourth face crossing the third face, and the fourth face includes a second face region that is continuous with the third face. The first face and the third face are along the third direction. The stacked body is provided between the first face region and the second face region. The stacked body includes a first magnetic layer, and a second magnetic layer provided between the first magnetic layer and the second face region. The second magnetic layer includes a second magnetic layer face facing the second face region.

Abstract: According to one embodiment, a magnetic head includes a first magnetic pole, a second magnetic pole, and a stacked body provided between the first and second magnetic poles. The stacked body includes first to fourth magnetic layers, and first to fifth non-magnetic layers. The second non-magnetic layer is in contact with the second and first magnetic layers. The third non-magnetic layer is in contact with the third and second magnetic layers. The fourth non-magnetic layer is in contact with the fourth and third magnetic layers. A fourth thickness of the fourth magnetic layer along a first direction from the first magnetic pole to the second magnetic pole is not less than 0.5 times and not more than 1.6 times a first thickness of the first magnetic layer along the first direction. A second thickness of the second magnetic layer along the first direction is less than the first thickness.

Abstract: According to one embodiment, a magnetic head includes first and second magnetic poles, a stacked body, and first to third terminals. The stacked body is provided between the first and second magnetic poles. The stacked body includes a first magnetic layer, a second magnetic layer between the first magnetic layer and the second magnetic pole, a third magnetic layer between the second magnetic layer and the second magnetic pole, a fourth magnetic layer between the third magnetic layer and the second magnetic pole, a first nonmagnetic layer between the first magnetic pole and the first magnetic layer, a second nonmagnetic layer between the first and second magnetic layers, a third nonmagnetic layer between the second and third magnetic layers, a fourth nonmagnetic layer between the third and fourth magnetic layers and a fifth nonmagnetic layer between the fourth magnetic layer and the second magnetic pole.

Abstract: According to one embodiment, a magnetic recording device includes a magnetic head and a controller. The magnetic head includes first and second magnetic poles, a magnetic element provided between the first magnetic pole and the second magnetic pole, first and second terminals electrically connected to one end and another end of the magnetic element, respectively, and a coil. The controller is electrically connected to the magnetic element and the coil, and performs a recording operation. In the recording operation, the controller supplies a recording current to the coil while applying an element voltage between the first and second terminals. When the applied voltage is changed while the recording current is supplied, a differential resistance of the magnetic element becomes a first differential resistance peak when the applied voltage is a first voltage, and becomes a second differential resistance peak when the applied voltage is a second voltage.

Abstract: According to one embodiment, a magnetic head includes a first magnetic pole, a second magnetic pole, and a stacked body provided between the first and second magnetic poles. The stacked body includes a first magnetic layer, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a third magnetic layer provided between the second magnetic layer and the second magnetic pole, a first non-magnetic layer provided between the first and second magnetic layers, a second non-magnetic layer provided between the second and third magnetic layers, a third non-magnetic layer provided between the first magnetic pole and the first magnetic layer, and a fourth non-magnetic layer provided between the third magnetic layer and the second magnetic pole. A first magnetic pole length is shorter than a second magnetic pole length. A first magnetic layer length is longer than a second magnetic layer length.

Abstract: According to one embodiment, a magnetic head includes first and second magnetic poles, and a stacked body provided between the first and second magnetic poles. The stacked body includes a first magnetic layer, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a first nonmagnetic layer provided between the first and second magnetic layers, a second nonmagnetic layer provided between the second magnetic layer and the second magnetic pole, and a third nonmagnetic layer provided between the first magnetic pole and the first magnetic layer. The first magnetic layer includes a first element including at least one of Fe, Co, or Ni. The second magnetic layer includes (Fe100-xCox)100-yEy. A second element E includes at least one selected from the group consisting of Cr, V, Mn, Yi, and Sc. The first magnetic layer does not include the second element.

Abstract: According to one embodiment, a data processing device includes a processor. The processor is configured to generate a first machine learning model based on a first generated data based on the first acquired data and a first other acquired data in the first operation. The first other data includes a first other feature value matrix with Np rows and D1 columns and a first other label with Np rows. The Np is an integer of 2 or more. The D1 is an integer of 1 or more. The first acquired data includes a first feature value matrix with N1 rows and D1 columns and a first acquired label with N1 rows. The first generated data includes a first generated matrix with (Np+N1) rows and (3×D1) columns and a first generated label with (Np+N1) rows. (Np+N1)/D1 is 250 or more.

Abstract: According to one embodiment, a magnetic head includes a first magnetic pole, a second magnetic pole, a magnetic element, and a magnetic member. The magnetic element is provided between the first and second magnetic poles, and includes a first magnetic layer. The magnetic member includes a first magnetic part. A second direction from the first magnetic part to the magnetic element crosses a first direction from the first to second magnetic pole. The first magnetic part includes a magnetic material including at least one of first to third materials. The first material includes at least one selected from the group consisting of Mn3Sn, Mn3Ge and Mn3Ga. The second material includes at least one selected from the group consisting of a cubic or tetragonal compound including Mn and Ni, a cubic alloy including ?-phase Mn, and a cubic alloy including Fe. The third material includes an antiferromagnet.

Abstract: According to one embodiment, a magnetic head includes first and second magnetic poles, a stacked body, and first to third terminals. The stacked body is provided between the first and second magnetic poles. The stacked body includes a first magnetic layer, a second magnetic layer between the first magnetic layer and the second magnetic pole, a third magnetic layer between the second magnetic layer and the second magnetic pole, a fourth magnetic layer between the third magnetic layer and the second magnetic pole, a first nonmagnetic layer between the first magnetic pole and the first magnetic layer, a second nonmagnetic layer between the first and second magnetic layers, a third nonmagnetic layer between the second and third magnetic layers, a fourth nonmagnetic layer between the third and fourth magnetic layers and a fifth nonmagnetic layer between the fourth magnetic layer and the second magnetic pole.

Abstract: According to one embodiment, a magnetic head includes first and second magnetic poles, and a stacked body provided between the first and second magnetic poles. The stacked body includes a first magnetic layer, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a first nonmagnetic layer provided between the first and second magnetic layers, a second nonmagnetic layer provided between the second magnetic layer and the second magnetic pole, and a third nonmagnetic layer provided between the first magnetic pole and the first magnetic layer. The first magnetic layer includes a first element including at least one of Fe, Co, or Ni. The second magnetic layer includes (Fe100-xCox)100-yEy. A second element E includes at least one selected from the group consisting of Cr, V, Mn, Yi, and Sc. The first magnetic layer does not include the second element.

Abstract: A magnetic head includes a first magnetic pole, a second magnetic pole, a magnetic element, and a magnetic member. The magnetic element is provided between the first and second magnetic poles, and includes a first magnetic layer. The magnetic member includes a first magnetic part. A second direction from the first magnetic part to the magnetic element crosses a first direction from the first to second magnetic pole. The first magnetic part includes a magnetic material including at least one of first to third materials. The first material includes at least one selected from the group consisting of Mn3Sn, Mn3Ge and Mn3Ga. The second material includes at least one selected from the group consisting of a cubic or tetragonal compound including Mn and Ni, a cubic alloy including ?-phase Mn, and a cubic alloy including Fe. The third material includes an antiferromagnet.

Abstract: A magnetic head includes a first magnetic pole, a second magnetic pole, and a stacked body provided between the first and second magnetic poles. The stacked body includes a first magnetic member, a second magnetic member provided between the first magnetic member and the second magnetic pole, a first layer provided between the first and second magnetic members, and a second layer provided between the second magnetic member and the second magnetic pole. The first magnetic member includes first magnetic regions and a first nonmagnetic region. The first nonmagnetic region is between the one of the first magnetic regions and the other one of the first magnetic regions.

Abstract: According to one embodiment, a magnetic head includes a first magnetic pole, a second magnetic pole, and a stacked body provided between the first and second magnetic poles. The stacked body includes first to fourth magnetic layers, and first to fifth non-magnetic layers. The second non-magnetic layer is in contact with the second and first magnetic layers. The third non-magnetic layer is in contact with the third and second magnetic layers. The fourth non-magnetic layer is in contact with the fourth and third magnetic layers. A fourth thickness of the fourth magnetic layer along a first direction from the first magnetic pole to the second magnetic pole is not less than 0.5 times and not more than 1.6 times a first thickness of the first magnetic layer along the first direction. A second thickness of the second magnetic layer along the first direction is less than the first thickness.