Abstract: The magnetic disk unit includes: a magnetic recording medium; a thermally-assisted magnetic recording head including a magnetic pole applying a recording magnetic field to the magnetic recording medium and a heating element heating the magnetic recording medium; and a controller allowing the heating element to perform a continuous heating operation at a first temperature for a first time period, and halting the heating operation of the heating element or allowing the heating element to perform a heating operation at a second temperature lower than the first temperature for a second time period that follows the first time period, the first time period having a length substantially equal to or less than a length of a time required for the magnetic recording medium to rotate one turn, and the second time period having a length substantially equal to or more than the length of the first time period.

Abstract: An estimation method includes a heating step in which a recording bit, on which a reference signal is recorded, is heated under each of heating conditions having different heating temperatures, the recording bit being at least one recording bit in the magnetic recording medium, and a measurement step in which a signal intensity with respect to the reference signal recorded in the recording bit after heating is measured under each of the heating conditions of the heating step. Based on the signal intensities with respect to the reference signal respectively measured in the measurement step, the distribution width of the Curie temperatures of the plurality of magnetic grains that form the magnetic recording layer is estimated.

Abstract: An estimation method includes a heating step in which a recording bit, on which a reference signal is recorded, is heated under each of heating conditions having different heating temperatures, the recording bit being at least one recording bit in the magnetic recording medium, and a measurement step in which a signal intensity with respect to the reference signal recorded in the recording bit after heating is measured under each of the heating conditions of the heating step. Based on the signal intensities with respect to the reference signal respectively measured in the measurement step, the distribution width of the Curie temperatures of the plurality of magnetic grains that form the magnetic recording layer is estimated.

Abstract: A measurement method of a magnetic field gradient of a recording magnetic field generated by a magnetic head in a recording medium includes a step of locally heating the recording medium in a nonmagnetic field state where a magnetic field is not applied to the recording medium at all and measuring a temperature gradient of the recording medium in the nonmagnetic field state, a step of locally heating the recording medium in a recording magnetic field application state where the recording magnetic field is applied to the recording medium and measuring a temperature gradient of the recording medium in the recording magnetic field application state, and a step of calculating a magnetic field gradient of the recording magnetic field based on the temperature gradient of the recording medium in the nonmagnetic field state and the temperature gradient of the recording medium in the recording magnetic field application state.

Abstract: Using a thermally-assisted magnetic recording device, a reference signal is recorded to a magnetic recording medium. After heating each of first and second heating points, where the first and second heating point being positioned respectively at inner and outer sides along a track width direction with respect to a track width center point of a recording bit where the reference signal is recorded, the reproducing signal intensity of the reference signal is measured. Then, obtaining a maximum distance between the first heating point and the second heating point when a reproducing signal intensity measurement value of the reference signal after the magnetic recording medium is heated is approximately zero. Based on the maximum distance, a characterization of the thermally-assisted magnetic recording device is evaluated.

Abstract: A thermally-assisted magnetic recording (TAMR) medium of the present invention includes: a magnetization direction arrangement layer on a substrate; and a magnetic recording layer on the magnetization direction arrangement layer, wherein the magnetization direction arrangement layer is made of at least one selected from a group consisting of Co, Zr, CoZr, CoTaZr, CoFeTaZrCr, CoNbZr, CoNiZr, FeCoZrBCu, NiFe, FeCo, FeAlN, (FeCo)N, FeAlSi, and FeTaC so that a spreading of the heating spot applied from the magnetic head for thermally-assisted recording to the film surface of the magnetic recording medium is suppressed, and that an SN is improved by arranging the magnetization direction of the perpendicularly written recording magnetization to become identical to a perpendicular direction, and realizing the higher recording density.

Abstract: A thermally-assisted magnetic recording head, includes: a pole that generates a writing magnetic field from an end surface that forms a portion of an air bearing surface opposing a magnetic recording medium; a waveguide through which light for exciting a surface plasmon propagates; a plasmon generator that couples to the light in a surface plasmon mode and generates near-field light from a near-field light generating portion on a near-field light generating end surface that forms the portion of the air bearing surface; and magnetic field focusing parts that are able to focus the writing magnetic field generated from the pole and that are disposed on both sides of the pole in a track width direction from a perspective of the air bearing surface side.

Abstract: A magnetic head slider includes a near-field light generator, an incorporated heater is activated to thermally-expand the magnetic head slider so that a first protrusion is generated on the air bearing surface, and a second protrusion protruding from the first protrusion is generated by a thermal expansion of the near-field light generator. A standard signal is written to a recording medium with a predetermined magnetization. A relation between a residual magnetization of the standard signal and a power of the heater is obtained by lowering the magnetization of the standard signal by heating the recording medium with the near-field light while light output of laser light is maintained to be constant and the power of the heater is varied. Further, a relation between the first spacing and the residual magnetization is obtained.

Abstract: A thermally-assisted magnetic recording head that includes an air bearing surface facing a recording medium and that performs a magnetic recording while heating the recording medium includes a waveguide configured with a core through which light propagates and a cladding that surrounds a periphery of the core and that includes at least a portion extending to the air bearing surface; and a heat radiation layer that is embedded in the cladding that surrounds the periphery of the core on the air bearing surface, and that is made of a material having a higher thermal conductivity coefficient than the cladding.

Abstract: A magnetic head slider includes a near-field light generator, an incorporated heater is activated to thermally-expand the magnetic head slider so that a first protrusion is generated on the air bearing surface, and a second protrusion protruding from the first protrusion is generated by a thermal expansion of the near-field light generator. A standard signal is written to a recording medium with a predetermined magnetization. A relation between a residual magnetization of the standard signal and a power of the heater is obtained by lowering the magnetization of the standard signal by heating the recording medium with the near-field light while light output of laser light is maintained to be constant and the power of the heater is varied. Further, a relation between the first spacing and the residual magnetization is obtained.

Abstract: A thermally-assisted magnetic recording head, includes: a pole that generates a writing magnetic field from an end surface that forms a portion of an air bearing surface opposing a magnetic recording medium; a waveguide through which light for exciting a surface plasmon propagates; a plasmon generator that couples to the light in a surface plasmon mode and generates near-field light from a near-field light generating portion on a near-field light generating end surface that forms the portion of the air bearing surface; and magnetic field focusing parts that are able to focus the writing magnetic field generated from the pole and that are disposed on both sides of the pole in a track width direction from a perspective of the air bearing surface side.

Abstract: A thermally-assisted magnetic recording (TAMR) medium of the present invention includes: a magnetization direction arrangement layer on a substrate; and a magnetic recording layer on the magnetization direction arrangement layer, wherein the magnetization direction arrangement layer is made of at least one selected from a group consisting of Co, Zr, CoZr, CoTaZr, CoFeTaZrCr, CoNbZr, CoNiZr, FeCoZrBCu, NiFe, FeCo, FeAlN, (FeCo)N, FeAlSi, and FeTaC so that a spreading of the heating spot applied from the magnetic head for thermally-assisted recording to the film surface of the magnetic recording medium is suppressed, and that an SN is improved by arranging the magnetization direction of the perpendicularly written recording magnetization to become identical to a perpendicular direction, and realizing the higher recording density.

Abstract: Provided is a method for forming a near-field light generating element, which is capable of sufficiently suppressing the unevenness of a waveguide surface and the distortion within the waveguide. The forming method comprises the steps of: forming a first etching stopper layer on a lower waveguide layer; forming a second etching stopper layer; forming, on the second etching stopper layer, a plasmon antenna material layer; performing etching with the second etching stopper layer used as a stopper, to form a first side surface of plasmon antenna; forming a side-surface protecting mask so as to cover the first side surface; and performing etching with the first and second etching stopper layers used as stoppers, to form the second side surface. By providing the first and second etching stopper layer, over-etching can be prevented even when each etching process takes enough etch time, which allows easy management of etching endpoints.

Abstract: A waveguide is provided, in which the optical coupling efficiency to a light source is sufficiently high, and the light-emitting spot center is stably provided at the intended position. The waveguide comprises a multilayered structure in which refractive indexes of layers having a surface contact with each other are different from each other. The multilayered structure is divided into a plurality of groups, and the length from the light-receiving end surface to the light-emitting end surface of one group is different from that of the neighboring group, and the protruded light-emitting end surface of the first group defined as a group that has the largest length includes a center of the light-emitting spot. In this waveguide, the state in which the light-emitting spot center is positioned within the light-emitting end surface does not easily be changed, even when the light-receiving spot center within the light-receiving end surface is rather displaced.

Abstract: A thermally-assisted magnetic recording head that includes an air bearing surface facing a recording medium and that performs a magnetic recording while heating the recording medium includes a waveguide configured with a core through which light propagates and a cladding that surrounds a periphery of the core and that includes at least a portion extending to the air bearing surface; and a heat radiation layer that is embedded in the cladding that surrounds the periphery of the core on the air bearing surface, and that is made of a material having a higher thermal conductivity coefficient than the cladding.

Abstract: A near-field light generating device includes: a base having a top surface; a waveguide that allows laser light to propagate therethrough and is disposed above the top surface of the base; and a surface plasmon generating element that is disposed above the top surface of the base so as to adjoin the waveguide in a direction parallel to the top surface of the base. The waveguide has a side surface that faces the surface plasmon generating element. The surface plasmon generating element includes: a coupling part that is opposed to a part of the side surface of the waveguide with spacing therebetween and causes excitation of a surface plasmon by coupling with evanescent light occurring from the part of the side surface; and a near-field light generating part that generates near-field light based on the surface plasmon excited at the coupling part.

Abstract: Provided is a surface plasmon antenna that can be set so that the emitting position on the end surface of the plasmon antenna where near-field light is emitted is located sufficiently close to the end of a magnetic pole. The surface plasmon antenna comprises an edge having a portion for coupling with a light in a surface plasmon mode. The edge is provided for propagating surface plasmon excited by the light and extends from the portion to a near-field light generating end surface that emits near-field light. The edge for propagating surface plasmon is a very narrow propagation region. Therefore, the near-field light generating end surface, which appears as a polished surface processed through polishing in the manufacturing of the plasmon antenna, can be made a shape with a very small size, and further can be set so that surface plasmon propagates to reach the end surface reliably.

Abstract: The thermally assisted magnetic head according to the present invention comprises a medium-facing surface, a main magnetic pole provided on the medium-facing surface, and a plasmon antenna provided on the medium-facing surface, in the vicinity of the main magnetic pole. The shape of the plasmon antenna, as viewed from a direction perpendicular to the medium-facing surface, is a triangle having first, second and third corners, the plasmon antenna being shaped as a flat plate the thickness direction of which is perpendicular to the medium-facing surface. The distance from the first corner to the main magnetic pole is shorter than the distance from the second corner to the main magnetic pole and the distance from the third corner to the main magnetic pole. The second corner and the third corner are rounded.

Abstract: In the magnetic recording apparatus, a recording layer is formed in a concavo-convex pattern, and recording elements are formed of convex portions of the concavo-convex pattern. Furthermore, the following equation (I) BL?ERL?BL+2×GL??(Equation (I)) is satisfied in each of tracks, where BL represents a length of the recording element in a circumferential direction, GL represents a length of a gap between the recording elements in the circumferential direction, and ERL represents an effective recording length which is a length of an effective recording area ER in the circumferential direction, the effective recording area ER being created on a magnetic recording medium by a heating head and a recording head.

Abstract: Provided is a near-field light generating element capable of avoiding excessive temperature rise, which comprises a waveguide and a near-field light generating layer. The layer comprises: a propagation surface on which surface plasmon excited by the light propagates; and a near-field light generating end at which near-field light is generated. The end is one end of the propagation surface. And a portion of the side surface of the waveguide is opposed to a portion of the propagation surface of the near-field light generating layer with a predetermined spacing so that the light propagating through the waveguide is coupled with the near-field light generating layer in a surface plasmon mode. The near-field light generating layer is preferably tapered toward the near-field light generating end.