WO2012008547A1 - Information recording head, information recording device, information recording method, and optical device - Google Patents

Information recording head, information recording device, information recording method, and optical device Download PDF

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Publication number
WO2012008547A1
WO2012008547A1 PCT/JP2011/066148 JP2011066148W WO2012008547A1 WO 2012008547 A1 WO2012008547 A1 WO 2012008547A1 JP 2011066148 W JP2011066148 W JP 2011066148W WO 2012008547 A1 WO2012008547 A1 WO 2012008547A1
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Prior art keywords
recording
recording medium
plasmon antenna
antenna
light
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PCT/JP2011/066148
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French (fr)
Japanese (ja)
Inventor
中川　活二
好人 芦澤
進一郎 大貫
伊藤　彰義
新 塚本
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学校法人日本大学
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Publication of WO2012008547A1 publication Critical patent/WO2012008547A1/en

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3109—Details
    • G11B5/313—Disposition of layers
    • G11B5/3133—Disposition of layers including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure
    • G11B5/314—Disposition of layers including layers not usually being a part of the electromagnetic transducer structure and providing additional features, e.g. for improving heat radiation, reduction of power dissipation, adaptations for measurement or indication of gap depth or other properties of the structure where the layers are extra layers normally not provided in the transducing structure, e.g. optical layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B2005/0002—Special dispositions or recording techniques
    • G11B2005/0005—Arrangements, methods or circuits
    • G11B2005/001—Controlling recording characteristics of record carriers or transducing characteristics of transducers by means not being part of their structure
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B2005/0002—Special dispositions or recording techniques
    • G11B2005/0005—Arrangements, methods or circuits
    • G11B2005/0021—Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal

Definitions

  • the present invention has an information recording head for recording information on a recording medium having a recording layer in which recording medium particles are dispersed, an information recording apparatus, an information recording method, and a function of changing a magnetic effect by laser light irradiation. It relates to the optical device method.
  • This is also called a granular type, in which a ferromagnetic polycrystalline thin film composed of a plurality of magnetic particles having high uniaxial magnetic anisotropy is provided on a medium, and magnetic particles are contained in one bit of recorded information. It is included in multiple numbers. As the recording density increases, the number of magnetic particles contained in one bit decreases, so that the magnetic flux decreases and noise increases. Until now, we have been increasing the density by reducing the size of the magnetic particles, but if the particle size is made smaller than this, the energy to hold magnetic information will be insufficient, and the thermal energy will be about room temperature. The information will be lost. Therefore, the use of a recording material having high magnetic stability has been studied as one method for increasing the density.
  • bit patterned media in which a magnetic recording layer is separated also in the track longitudinal direction and one magnetic particle is recorded as one bit. This is a structure in which a magnetic layer is physically separated for each magnetic particle, and a magnetic material is evenly arranged as a bit carrier in the track longitudinal direction (see, for example, Patent Document 1).
  • the inventors of the present application as a bit-patterned medium that records one magnetic particle as one bit, laminates an underlayer on which a minute concave portion is uniformly exposed on a substrate.
  • An amorphous magnetic film is laminated on the surface of the underlayer in which the concave portion is exposed.
  • the underlayer is made of tetraethoxysilane as a raw material, and is spherical in self-alignment evenly in a face-centered cubic structure.
  • Magnetic disk memory is an important file memory system that supports today's computer society, but the physical limit of the response speed of magnetic materials is approaching, and large-capacity data will be recorded at an appropriate speed in the near future. Becomes impossible.
  • Non-Patent Document 1 and Patent Document 2 As a new technique for overcoming this problem, the inventors of the present application have proposed a recording method using circularly polarized light in which the magnetization state is controlled by circularly polarized light (see, for example, Non-Patent Document 1 and Patent Document 2). ).
  • a magneto-optic comprising a magnetizable medium and an irradiation system adapted to impart angular momentum to the magnetic spin system of the magnetizable medium so as to selectively orient the magnetization of the medium
  • the switching element allows information “bits” to be recorded as regions of opposite magnetization or spin.
  • the spin state in the magnetic material can be manipulated with appropriate angular momentum irradiation, especially using circularly or elliptically polarized light.
  • An effective magnetic field is generated to orient the magnetization of the magnetic domains and can be used to locally heat the material at the same time.
  • a circularly polarized laser pulse acts on spins through spin orbit coupling as an effective magnetic field, and this effect is known as an inverse Faraday effect.
  • the magnitude of this magnetic field is proportional to the magneto-optic constant that does not vary with temperature in the first order approximation. Therefore, phenomenologically, the overall effect is the heating of the magnetic system plus the application of an effective magnetic field due to the inverse Faraday effect. Switching is very efficient due to the magnetic susceptibility diffusing near the Curie temperature.
  • the magnetization can be reversed only by irradiation of a single pulse having a pulse length of 40 fs (femtosecond: 10-15 seconds) to a GdFeCo thin film using circularly polarized light using a femtosecond pulse laser as a light source.
  • the light-spin action is equivalent to the application of a magnetic field in the direction of light travel, and can be controlled by selecting circularly polarized helicity (clockwise or counterclockwise). I can explain.
  • JP 2009-163816 A WO2005 / 081233 Special table 2009-538490 gazette
  • Non-Patent Document 2 it has been reported that plasmon resonance occurs in circularly polarized light (see, for example, Non-Patent Document 2), and it is conceivable to use near-field light to create local circularly polarized light.
  • the inventors of the present application conducted a circular polarization analysis in the vicinity of the nanometer-size cross-shaped aperture antenna and announced that a mode close to circular polarization near the nanometer-size cross-shaped aperture antenna can be formed with the recording medium disposed.
  • a mode close to circular polarization near the nanometer-size cross-shaped aperture antenna can be formed with the recording medium disposed.
  • an object of the present invention is to provide an information recording head, an information recording apparatus, and an information recording apparatus that simultaneously realize high speed and high density in recording information by direct magnetization reversal by circularly polarized light in view of the conventional situation as described above. It is to provide a method.
  • Another object of the present invention is to provide an optical device method having a function of changing a magnetic effect by irradiation with a laser beam.
  • the interaction between the recording medium particles and the nanometer-sized rotationally symmetric opening having a substantially rotational symmetry with the traveling direction of the irradiated recording light as an axis. Is used to generate circularly polarized light locally in the recording medium particles and record information by direct magnetization reversal.
  • the present invention is an information recording head for recording information with a laser beam on a recording medium having a recording layer in which recording medium particles are dispersed, and the upper recording medium dispersed in the recording layer of the recording medium
  • a plasmon antenna having a shape with substantially rotational symmetry about the traveling direction of the recording light irradiated with a size larger than the particle, and excited by the laser light applied as the recording light to the plasmon antenna, Directly magnetized by generating circularly polarized light or elliptically polarized light in the recording medium particles due to the interaction between the recording medium particles dispersed in the recording layer of the recording medium positioned facing the antenna and the plasmon antenna. Information is recorded by inversion.
  • the rotational symmetry of the plasmon antenna is preferably four-fold symmetry.
  • the present invention also relates to an information recording apparatus, comprising: a recording medium having a recording layer in which recording medium particles are dispersed; and a substantially rotation about an advancing direction of recording light irradiated with a larger size than the upper recording medium particles
  • a plasmon antenna having a symmetrical shape ; and a light source for irradiating the plasmon antenna with laser light as the recording light.
  • the plasmon antenna is excited by the laser light irradiated as the recording light, and is applied to the plasmon antenna. Due to the interaction between the recording medium particles dispersed in the recording layer of the recording medium facing each other and the plasmon antenna, circularly or elliptically polarized light is generated in the recording medium particles, and direct magnetization reversal. It is characterized by recording information.
  • the rotational symmetry is preferably four-fold symmetry.
  • the light source may irradiate a short pulse laser beam.
  • the recording medium may be a bit patterned medium in which a plurality of bit carriers for recording one magnetic particle as one bit are arranged.
  • the recording medium can be a recording medium having a granular structure in which nanoscale fine metal particles are dispersed in an insulating matrix.
  • the present invention also relates to an information recording method for recording information on a recording medium having a recording layer in which recording medium particles are dispersed with a laser beam, the traveling direction of the recording light irradiated with a size larger than the recording medium particles.
  • a laser beam as the recording light is irradiated to a plasmon antenna having a substantially rotational symmetry with the axis as the axis, excited by the laser light irradiated as the recording light to the plasmon antenna, and opposed to the plasmon antenna.
  • Information is recorded by direct magnetization reversal by generating circularly or elliptically polarized light in the recording medium particles by the interaction of the recording medium particles dispersed in the recording layer of the recording medium positioned and the plasmon antenna. It is characterized by doing.
  • the information recording method according to the present invention can irradiate the plasmon antenna having a 4-fold symmetry with a short pulse laser beam as the recording light.
  • the present invention is an optical device having a function of changing a magnetic effect by laser light irradiation, wherein the magnetic particle part whose magnetization direction is changed by the laser light irradiation is arranged in contact with the magnetic particle part.
  • At least one magnetic body portion and a plasmon antenna having a substantially rotational symmetry with the traveling direction of laser light irradiated in a larger size than the magnetic particle portion as an axis, and irradiating the plasmon antenna Generated by circularly or elliptically polarized light in the magnetic body portion by the interaction between the plasmon antenna and the magnetic body portion which is excited by the laser beam and is positioned opposite to the plasmon antenna.
  • the magnetic action of the magnetic body portion arranged in contact with the magnetic particle portion is changed.
  • An optical device includes two magnetic body portions arranged in contact with the magnetic particle portion, and circularly polarized light or elliptical light is formed in the magnetic body portion by interaction between the magnetic body portion and the plasmon antenna. It is possible to change the magnetoresistance between two magnetic body portions arranged in contact with the magnetic particle portion by generating polarized light and directly reversing the magnetization.
  • a plasmon antenna having a rotationally symmetric aperture having a substantially rotational symmetry with the traveling direction of recording light irradiated at a nanometer size larger than the recording medium particles as an axis is irradiated as the recording light.
  • Recording medium particles excited by the femtosecond pulsed laser light and dispersed in the recording layer of the recording medium located opposite the rotational characteristic aperture of the plasmon antenna, and a rotationally symmetric aperture of the plasmon antenna By generating circularly polarized light in the above recording medium particles and directly recording information by magnetization reversal, the high speed and high density can be realized at the same time. Although only size recording could be performed, recording at a size of several tens of nanometers can be made possible.
  • the present invention when recording information by direct magnetization reversal by circularly polarized light, the above-described interaction between the recording medium particles dispersed in the recording layer of the recording medium and the rotationally symmetric aperture of the plasmon antenna, it is possible to provide an information recording head, an information recording apparatus, and an information recording method that simultaneously realize high speed and high density.
  • the magnetic body portion excited by the laser light applied to the plasmon antenna and positioned opposite to the plasmon antenna and the plasmon antenna interacts with the circularly polarized light in the magnetic body portion.
  • the magnetic action of the magnetic body portion arranged in contact with the magnetic particle portion can be changed.
  • FIG. 1 is a perspective view showing a schematic configuration of an information recording apparatus to which the present invention is applied.
  • FIG. 2 is a block diagram schematically showing the main configuration of the information recording apparatus.
  • 3A and 3B are schematic views showing a simulation model of a plasmon head provided in an information recording head in the information recording apparatus.
  • 4A to 4D are diagrams schematically showing structural examples of a solid antenna having a three-dimensional shape having rotational symmetry.
  • 5A to 5D are diagrams schematically showing an example of the structure of a four-fold symmetry antenna.
  • 6A to 6D are diagrams schematically showing an example of the structure of a two-fold symmetry antenna.
  • 7A and 7B are diagrams illustrating time distributions of electromagnetic fields of a four-fold symmetrical aperture antenna.
  • FIG. 8A and 8B show the pointing vector SZ in the magnetic medium direction (+ Z direction) and the phase difference ⁇ between the electric field and the magnetic field in the XY plane at the observation center at the center of the aperture of the 4-fold symmetrical aperture antenna.
  • FIG. 9 is a diagram illustrating a spatial distribution of the Z-direction component SZ of the pointing vector in the cross aperture antenna and the circular aperture antenna.
  • 10A and 10B are schematic diagrams illustrating a simulation model of a cross aperture antenna in which a cross-shaped aperture is opposed to a Co continuous recording medium.
  • FIG. 11 is a diagram showing the dependence of the angle ⁇ formed by the electric field E and the magnetic field H in the simulation model XY plane of the cross aperture antenna shown in FIG.
  • FIGS. 14A to 14C are diagrams showing the results of evaluating each electric field intensity I on a Co continuous recording medium in a simulation model of a cross aperture antenna and a circular aperture antenna when there is no antenna.
  • FIG. 13 is a diagram showing each degree of circular polarization C on the A-A ′ line, the AB line, and the A-A ′ line in FIG. 12.
  • FIGS. 14A to 14C are diagrams showing the results of evaluating each electric field intensity I on a Co continuous recording medium in a simulation model of a cross aperture antenna and a circular aperture antenna when there is no antenna.
  • FIG. 12A to 12C are diagrams showing the results of evaluating each degree of circular polarization C on a Co continuous recording medium in a simulation model of a cross aperture antenna and a circular aperture antenna when there is no antenna.
  • FIG. 15 is a diagram showing each electric field intensity I on the lines A-A ′, AB, and A-A ′ in FIG. 14.
  • FIG. 16A to FIG. 16C are diagrams showing the results of evaluating each performance index F on a Co continuous recording medium in a simulation model of a cross aperture antenna and a circular aperture antenna when there is no antenna.
  • FIG. 17 is a diagram showing each figure of merit F on the A-A ′ line, AB line, and A-A ′ line in FIG. 16.
  • FIG. 18 is a diagram showing a simulation model for simulating the pointing vector S, the electric field E, the magnetic field H, and the phase difference ⁇ at the observation position on the bit carrier in the plasmon head shown in FIG.
  • 19A to 19C are diagrams showing the degree of circular polarization S, the electric field strength I, and the figure of merit F in the XZ plane of the simulation model of the cross aperture antenna.
  • 20A and 20B are diagrams showing the degree of circular polarization S in the XZ plane and the direction cosine SZ /
  • FIG. 21 is a diagram showing the phase difference distribution in the recording medium direction (+ Z direction) and the direction cosine SZ /
  • FIG. 22A to 22C show the phase difference distribution in the direction of the recording medium (+ Z direction) and the direction cosine SZ /
  • FIG. 23 is a diagram showing a phase difference distribution in the recording medium direction (+ Z direction) and a direction cosine SZ /
  • It is. 24A and 24B are schematic views showing other simulation models of the plasmon head provided in the information recording head in the information recording apparatus.
  • FIG. 25A to 25C show the degree of circular polarization S ′ in the XZ plane, the direction cosine SZ /
  • FIG. FIG. 26A to FIG. 26C show other simulation models of the above plasmon head in which the circular polarization degree S ′ in the XZ plane when the incident circularly polarized light is reversed and the direction cosine SZ / in the recording medium direction (+ Z direction). It is a figure which shows
  • 27A and 27B are diagrams schematically showing an example of the structure of a magneto-resistive effect device to which the present invention is applied.
  • the present invention is applied to an information recording apparatus 100 that records information on a bit patterned medium 10 in which a plurality of bit carriers 15 made of a magnetic material are arranged on a medium substrate, as shown in FIGS. 1 and 2, for example.
  • the information recording apparatus 100 includes a bit patterned medium 10, an information recording head 20, a detection unit 30, and a control unit 40, and directly detects the arrangement position of the bit carrier 15 of the bit patterned medium 10 by the detection unit 30. Then, the recording operation is controlled by the control unit 40 using the detection signal as a recording clock signal, and information is recorded on the bit carrier 15 of the bit patterned medium 10 by the information recording head 20 bit by bit. is there.
  • bit patterned medium 10 used as a recording medium a plurality of bit carriers (recording carriers) 15 made of a magnetic material are arranged on a substrate.
  • the bit carrier 15 is formed so that one bit corresponds to one bit carrier, for example, by a semiconductor manufacturing process or the like. For example, as shown in a partially enlarged view of FIG. Thus, it is separated into a magnetic region serving as a bit carrier and a nonmagnetic region serving as the other region.
  • the present invention is not limited to the bit patterned medium formed with physical unevenness, and any structure may be used as long as the medium is configured to be a 1-bit carrier.
  • a medium that is magnetically separated by changing the composition or the film structure may be used.
  • a high-density magnetic fine particle film is fabricated by using a SiO2 film with nanoscale vacancies inside a face-centered cubic structure (Face-Centered Cubic ⁇ ⁇ ) array using a polymer self-organization phenomenon as an underlayer.
  • An ultra-high-density recording medium in which nanometer-size magnetic fine particles with a high packing density are formed on a template substrate on which nanometer-size irregularities are exposed by periodically arranging the surface of a porous SiO2 film by Ar ion etching is used. be able to.
  • the information recording head 20 is excited by a light source unit 21 using a semiconductor laser that emits a recording laser beam whose emission timing is controlled by the control unit 40, and a laser beam emitted as the recording light from the light source unit 21, It comprises a plasmon antenna 22 having a nanometer-size opening 22A for generating circularly polarized light inside the bit carrier 15 on the bit patterned medium 10.
  • the light source unit 21 emits a femtosecond pulsed laser beam having a wavelength ⁇ of 780 nm, for example, as a recording laser beam whose emission timing is controlled by the control unit 40.
  • the detecting unit 30 detects the arrangement position of the bit carrier 15 before recording on the bit carrier 15 by the information recording head 20. That is, the detection unit 30 detects the arrangement position of the bit carrier 15 to be recorded before recording.
  • the bit carrier 15 is manufactured by a high-precision process. However, as the arrangement pitch of the bit carrier 15 becomes finer, for example, 25 nm pitch in order to increase the recording density, the influence of the displacement of the arrangement position due to the production error can be ignored. It will disappear.
  • the detection unit 30 is provided to detect the arrangement position of the bit carrier 15 in order to compensate for this deviation, detects the arrangement position of the bit carrier 15, and based on this, the correlation signal corresponding to this arrangement position is detected. Is output.
  • Various methods for detecting the arrangement position of the bit carrier 15 can be used.
  • the physical phenomenon change include a light intensity change, a capacitance change, a magnetic change, an eddy current change, and a sound wave reflection time change with respect to the bit carrier 15.
  • the near-field light intensity changes depending on the arrangement position of the bit carrier 15, and this is detected.
  • the capacitance the fact that the capacitance between the metal plates changes depending on the arrangement position of the bit carrier 15 is utilized.
  • the change in hardness can be detected by detecting the change in magnetism with a magnetic sensor, detecting the change in eddy current generated in the metal plate, or measuring the time when the reflected wave returns by irradiating ultrasonic waves. By detecting it, the arrangement position of the bit carrier 15 can be detected.
  • the control unit 40 controls the recording timing of the information recording head 20 on the bit carrier 15 using the correlation signal obtained by the detection unit 30. That is, after the position of the bit carrier 15 is detected, the information recording head 20 performs recording in accordance with the arrangement position.
  • the control unit 40 only needs to be configured to output a clock signal that determines the recording timing by the information recording head 20, and by using a correlation signal corresponding to a change in the arrangement position of the bit carrier 15 as this clock signal.
  • the arrangement position of the bit carrier 15 can be detected and used as it is as a clock signal.
  • the arrangement position changes before recording by the information recording head 20. Can be detected by the detection unit 40, and recording can be accurately performed on the bit carrier 15 at the same timing. Note that recording may be performed by outputting a clock signal delayed by a predetermined timing depending on the relationship between the rotation speed of the recording medium and the distance between the information recording head and the detection unit.
  • the information recording apparatus 100 excites the plasmon antenna 22 by irradiating the plasmon antenna 22 having the nanometer size opening 22A with femtosecond pulsed laser light having a wavelength ⁇ of 780 nm emitted from the light source unit 21. Then, circularly polarized light is locally generated by the interaction between the plasmon antenna 22 and the bit carrier 15 on the bit patterned medium 10. As a result, the bit carrier 15 is directly magnetized by circularly polarized light without an external magnetic field, and 1-bit information is recorded.
  • the light source unit 21 is provided outside the information recording head 20, and a light guide path for irradiating the plasmon antenna 22 with femtosecond pulsed laser light having a wavelength ⁇ of 780 nm emitted from the light source unit is provided to the information recording head 20. You may make it provide.
  • the plasmon antenna 22 that generates circularly polarized light locally by interaction with the bit carrier 15 on the bit patterned medium 10 has a nanometer-sized shape having rotational symmetry about the traveling direction of light.
  • An aperture antenna having an aperture 22A is used.
  • a cross-opening antenna provided with a cross-shaped aperture 22 ⁇ / b> A is used as the plasmon antenna 22.
  • the information recording head 20 in the information recording apparatus 100 records information on a recording medium having a recording layer in which recording medium particles are dispersed by femtosecond pulsed laser light.
  • the recording is provided with a plasmon antenna 22 having an opening 22A, and is excited by femtosecond pulsed laser light applied to the plasmon antenna 22 as the recording light, and is positioned facing the rotationally symmetric opening 22A of the plasmon antenna 22.
  • Recording medium particles dispersed in the recording layer of the medium, and the plasmon antenna 2 By interaction with rotational symmetry opening 22A of recording information by direct magnetization reversal by generating a circularly polarized light on the recording medium in the particles.
  • the cell size was 1 ⁇ 1 ⁇ 1 nm 3.
  • the rotationally symmetric antenna includes an aperture antenna and a linear antenna having a rotational symmetry, and three-dimensional antennas 110A and 110B having a rotational symmetry as shown in FIGS. 4A to 4D, for example. 110C, 110D, etc.
  • the four-fold symmetry antenna has two sets of aperture antennas, linear antennas or three-dimensional antennas formed in a shape having rotational symmetry, and is arranged four-fold symmetrically. It has a structure.
  • FIG. 5A shows a four-fold symmetric antenna 221A, which is a four-fold symmetric aperture antenna in which an opening having four-fold symmetry is provided in a metal plate.
  • a 4-fold symmetrical antenna 221B shown in FIG. 5B is a 4-fold symmetrical linear antenna in which linear antennas are arranged so as to have 4-fold symmetry.
  • a 4-fold symmetrical antenna 221C shown in FIG. 5C is a 4-fold symmetrical solid antenna in which spherical solid antennas having a rotational symmetry are arranged so as to have a 4-fold symmetry.
  • a 4-fold symmetrical antenna 221D shown in FIG. 5D is a 4-fold symmetrical solid antenna in which spherical three-dimensional antennas having rotational symmetry are arranged so as to have 4-fold symmetry.
  • the two-fold symmetry antenna has a structure in which the size and shape of the two pairs of rotationally symmetric antennas facing each other are changed as shown in the structural examples in FIGS. 6A to 6D.
  • the 2-fold symmetric antenna 222A shown in FIG. 6A is a 2-fold symmetric aperture antenna having two sets of rotationally symmetric apertures of different sizes provided so as to have a 2-fold symmetry in a metal plate.
  • 6B is a two-fold symmetric linear antenna in which two sets of linear antennas having different sizes are arranged so as to have two-fold symmetry.
  • a two-fold symmetric antenna 222C shown in FIG. 6C is a two-fold symmetric three-dimensional antenna in which two sets of spherical three-dimensional antennas with different sizes are arranged so as to have two-fold symmetry.
  • a two-fold symmetric antenna 222D shown in FIG. 6D is a two-fold symmetric three-dimensional antenna in which two sets of spherical three-dimensional antennas having different sizes are arranged so as to have two-fold symmetry.
  • the plasmon antenna 22 may be an antenna having two-fold symmetry in principle.
  • the electric field component has the same magnitude of the X direction component EX and the Y direction component EY
  • the magnetic field component has the same magnitude of the X direction component HX and the Y direction component HY
  • the electric field component and the magnetic field component have the same magnitude.
  • the phase difference is shifted by ⁇ / 4.
  • the four-fold symmetric aperture antenna has a propagation direction and a phase difference ⁇ between the electric field and the magnetic field when SZ /
  • ⁇ tan-1 (EX / EY) -tan-1 (HX / HY) Is suitable for use as a plasmon antenna that generates circularly polarized light.
  • the spatial distribution of the Z-direction component SZ of the pointing vector in the cross aperture antenna and the circular aperture antenna propagates high energy locally.
  • a cross-shaped aperture 22A ′ in which rectangles having a long side length L and a short side length W are orthogonal to each other is formed into a silver (Ag) plate 22B.
  • L 100 to 400 nm
  • W 20 nm
  • incident light is incident in the + Z axis direction
  • the intensity distribution has a central peak electric field of 1 V / M Gaussian distribution
  • the pointing vector S is stably directed to the recording medium direction (+ Z axis direction). Focused on being.
  • the angle ⁇ formed by the electric field E and the magnetic field H in the XY plane is always 90 ° to 130 ° regardless of the length L of the long side of the opening within the analyzed range.
  • ) was always 0.995 or more.
  • a mode close to circularly polarized light can be formed in the vicinity of a nanometer-sized cross-open antenna with a recording medium arranged.
  • the parameter SI indicating the light intensity
  • the parameter SQ indicating the horizontal dominant component
  • the parameter SC indicating the + 45 ° dominant component
  • the Stokes parameter SI, SQ, SC in which the parameter SS indicating the circle dominant component is represented by the average value of the electric field.
  • SS SI ⁇ EX2> + ⁇ EY2>
  • SQ ⁇ EX2>- ⁇ EY2>
  • SC ⁇ 2EXEY cosr>
  • SS ⁇ 2EXEYsinr>
  • Table 1 it is possible to evaluate what the polarization is, that is, clockwise circularly polarized light, linearly polarized light, linearly polarized light shifted by 45 °, or elliptically polarized light.
  • EX is the X component of the electric field
  • EY is the Y component of the electric field
  • r is the phase difference between the X component EX and the Y component EY of the electric field
  • ⁇ > is the time average.
  • the circular polarization degree C, the electric field strength I, and the figure of merit for the simulation model of the cross aperture antenna and the circular aperture antenna are obtained by using the following equations obtained by extending the Stokes parameters SI, SQ, SC, and SS.
  • the evaluation results of F are shown in FIGS.
  • FIG. 12A to 12C show the respective circular polarization degrees C on the Co continuous recording medium 250 when there is no antenna, when a cross aperture antenna is provided, and when a circular aperture antenna is provided, and FIG. 12A to 12C show the respective circular polarization degrees C on the AA ′ line, AB line, and AA ′ line.
  • FIG. 14A to 14C show electric field strengths I on the Co continuous recording medium 250 when there is no antenna, when a cross aperture antenna is provided, and when a circular aperture antenna is provided, and FIG. 14A to 14C show the electric field intensities I on the AA ′ line, AB line, and AA ′ line.
  • FIGS. 16A to 16C show performance indexes F on the Co continuous recording medium 250 when there is no antenna, when a cross aperture antenna is provided, and when a circular aperture antenna is provided, and FIG.
  • the figure of merit F on the AA ′ line, AB line, and AA ′ line in FIGS. 16A to 16C is shown.
  • the plasmon antenna 22 having the nanometer-size opening 22A for generating circularly polarized light inside the bit carrier 15 on the bit patterned medium 10 is used four times as shown in FIGS. 3A and 3B.
  • Symmetric aperture antenna that is, a cross aperture in which a cross-shaped aperture 22A in which rectangles having a long side length L and a short side length W are orthogonal to each other is provided in a silver (Ag) plate 22B
  • L 150 nm
  • W 20 nm
  • incident light is incident in the + Z-axis direction
  • circularly polarized light with a wavelength ⁇ 780 nm
  • intensity distribution is a Gaussian distribution with a central peak electric field of 1 V / m
  • FH 5 nm
  • FIGS. 19A to 19C show the degree of circular polarization S, the electric field intensity I, and the figure of merit F in the XZ plane of the simulation model of the cross aperture antenna
  • FIGS. 20A and 20B show the above-mentioned FIG. 21 shows the circular polarization degree S in the XZ plane and the direction cosine SZ /
  • 2 shows the phase difference distribution in the recording medium direction (+ Z direction) and the direction cosine SZ /
  • FIG. 23 shows the phase difference distribution in the recording medium direction (+ Z direction) and the direction cosine SZ /
  • the rotationally symmetric opening 22A having a rotational symmetry about the traveling direction of the recording light irradiated with a nanometer size larger than the bit carrier 15 on the bit patterned medium 10 is used. Is irradiated with femtosecond pulsed laser light as the recording light, and excited by the femtosecond pulsed laser light irradiated as the recording light onto the plasmon antenna 22, and the rotationally symmetric aperture 22 ⁇ / b> A of the plasmon antenna 22. Due to the interaction between the bit carrier 15 on the bit patterned medium 10 and the rotationally symmetric aperture 22A of the plasmon antenna 22 which is located opposite to the circularly polarized light in the bit carrier 15 to generate direct magnetization. Record information by inversion.
  • circularly polarized light is locally generated by utilizing the interaction between the nanometer-size opening 22A formed in the plasmon antenna 22 and the recording medium particle 15, and information is obtained by direct magnetization reversal. By recording this, it is possible to simultaneously realize high speed and high density.
  • a cross-shaped aperture antenna is used as the plasmon antenna 22 having the nanometer-size aperture 22A facing the bit carrier 15 on the bit patterned medium 10 as described above. That is, although a 4-fold symmetrical aperture antenna is used, in principle, any antenna having a 2-fold symmetry with the traveling direction of the irradiated light as an axis may be used.
  • the plasmon antenna 22 only needs to have a shape having substantially rotational symmetry about the traveling direction of the irradiated light.
  • a short pulse laser beam can be used as the light irradiating the plasmon antenna 22.
  • information is recorded for each bit by the plasmon antenna 22 having the nanometer size opening 22A with respect to the bit carrier 15 on the bit patterned medium 10, but the information is recorded in the insulating matrix.
  • Information may be recorded by the plasmon antenna 22 on fine metal particles of a granular structure recording medium in which nanoscale fine metal particles are dispersed.
  • the wavelength ⁇ irradiated to the nanometer-size opening 22A of the plasmon antenna 22 is 780 nm.
  • the femtosecond pulsed laser beam circularly polarized light is generated in the resonated fine metal particles, and information is recorded.
  • the simulation model of the antenna the vicinity of the aperture antenna using “Poynting” manufactured by Fujitsu, which is a commercially available general-purpose three-dimensional electromagnetic analysis software, as simulation software for the FDTD method (Finite-difference time-domain method; FDTD method)
  • FDTD method Finite-difference time-domain method
  • a simulation model of a cross aperture antenna in which an aperture 122A is provided on a square silver (Ag) plate 122B of 2000 nm ⁇ 2000 nm is arranged in a matrix with Co recording medium particles 150 having a diameter of 15 nm separated by 10 nm. It was made to oppose the recording medium.
  • 25A to 25C show the degree of circular polarization S ′ in the XZ plane, the direction cosine SZ /
  • the electric field intensity I ′ of the recording medium particle 150 located in the periphery was 0.21 [(V / m) 2], whereas the recording medium located in the center.
  • the electric field intensity I ′ in the particle 150 is 0.6 [(V / m) 2], and the electric field intensity can be locally increased in the central portion of the simulation model of the cross aperture antenna.
  • the information recording apparatus including the information recording head to which the present invention is applied has been described.
  • the present invention is not limited to the above embodiment.
  • a device that utilizes a change in magnetic interaction between magnetic bodies by contacting another magnetic body with a magnetic body that changes the magnetization direction can be an optical device that can be controlled by laser light irradiation.
  • FIG. 27A and FIG. 27B show a configuration example of a magnetoresistive element that is an optical device that can be controlled by laser light irradiation.
  • the magnetoresistive element 200 includes a cylindrical magnetic particle part 210 whose magnetization direction is changed by being irradiated with laser light, and two magnetic body parts 221 and 222 in contact with the cylindrical magnetic particle part 210 (which are magnetized).
  • the end of the cylindrical magnetic particle 210 is positioned at the center of the cross opening 230A of the plasmon antenna 230.
  • the magnetoresistive element 200 is an optical device having a function of changing a magnetic effect by laser light irradiation, and includes a magnetic particle portion 210 whose magnetization direction is changed by the laser light irradiation, and the magnetic particle portion.
  • the magnetoresistive element 200 is excited by the laser light applied to the plasmon antenna 230, and interacts with the magnetic particle part 210 positioned opposite the plasmon antenna 230 and the plasmon antenna 230. Then, circularly or elliptically polarized light is generated in the magnetic particle part 210 and the magnetic action of the magnetic body parts 221 and 222 disposed in contact with the magnetic particle part 210 is changed by direct magnetization reversal.
  • the magnetization direction of the cylindrical magnetic particle part 210 When the magnetization direction of the cylindrical magnetic particle part 210 is changed by the irradiation of the laser beam, the magnetization direction of the two magnetic body parts 221 and 222 in contact therewith (the magnetization direction is fixed upward) When the magnetization direction of the cylindrical particle part 210 is directed upward, the resistance between AB is small, and the resistance between AB is large in the reverse direction (there may be the opposite depending on the magnetic material).
  • the method of the present invention can be used for high-speed operation of any magnetic device that exhibits a function by reversing the magnetization.

Abstract

In the present disclosures, a plasmon antenna (22) having a rotationally symmetrical opening (22A) having a shape that is roughly rotationally symmetrical around an axis in the direction of progress of recording light radiated at a nanometer size that is larger than bit carriers (15) on bit patterned media (10) is irradiated with femtosecond pulse laser light as the abovementioned recording light, and is excited by the femtosecond pulse laser light radiated as the abovementioned recording light at the abovementioned plasmon antenna (22), and by means of the interaction of the bit carrier (15) on the abovementioned bit patterned media (10) positioned facing the rotationally symmetrical opening (22A) of the abovementioned plasmon antenna (22) and the rotationally symmetrical opening (22A) of the abovementioned plasmon antenna (22), circularly polarized light is generated within the abovementioned bit carrier (15) and information is recorded by means of direct magnetization reversal.

Description

情報記録ヘッド、情報記録装置、情報記録方法及び光デバイスInformation recording head, information recording apparatus, information recording method, and optical device
　本発明は、記録媒体粒子が分散された記録層を有する記録媒体に情報をレーザ光により記録する情報記録ヘッド、情報記録装置、情報記録方法及びレーザ光の照射により磁気効果を変化させる機能を有する光デバイス法に関する。
　本出願は、日本国において２０１０年７月１６日に出願された日本特許出願番号２０１０－１６１９９６を基礎として優先権を主張するものであり、これらの出願は参照することにより、本出願に援用される。 The present invention has an information recording head for recording information on a recording medium having a recording layer in which recording medium particles are dispersed, an information recording apparatus, an information recording method, and a function of changing a magnetic effect by laser light irradiation. It relates to the optical device method.
This application claims priority on the basis of Japanese Patent Application No. 2010-161996 filed on Jul. 16, 2010 in Japan. These applications are incorporated herein by reference. The
　近年の情報社会においてデジタル化が加速し、大容量の記録装置の要求は益々高まっている。磁気記録装置として現在実用化されているものは、その磁気記録媒体として強磁性多結晶薄膜を有するものが用いられている。 In recent years, digitalization has accelerated in the information society, and the demand for large-capacity recording devices is increasing. What is currently put into practical use as a magnetic recording apparatus is a magnetic recording medium having a ferromagnetic polycrystalline thin film.
　これは、グラニュラータイプとも呼ばれるものであり、高い一軸磁気異方性を持つ複数の磁性粒子からなる強磁性多結晶薄膜が媒体に設けられており、記録した情報の１ビットの中に磁性粒子が複数含まれているものである。記録密度が増加していくと、１ビットに含まれる磁性粒子の数が減るため磁束も減少し、ノイズが増加することになる。これまでは磁性粒子のサイズを小さくすることで高密度化を進めてきていたが、粒子サイズをこれ以上小さくすると、磁気情報を保持するエネルギーが不足してしまい、室温程度の熱エネルギーであっても情報が消えてしまうことになる。そこで、高密度化を進めるための一つの方法として、高い磁気安定性を有する記録材料を使うことも研究されている。しかしながら、磁性粒子の安定性が高いと、従来の磁気ヘッドでの記録が不可能になるという問題もある。このため、磁気ヘッドにより記録を行う前に、熱（光）により一時的に磁性粒子の保磁力を低下させて記録を行う光アシスト型の磁気記録装置も提案されている。さらに、より高密度化を目指すべく、トラック長手方向についても磁気記録層を分離して、１つの磁性粒子を１ビットとして記録するビットパターンドメディアが提案されている。これは、１つの磁性粒子ごとに物理的に磁性層が分離されており、ビット担体として磁性体を均等にトラック長手方向に配置した構造である（例えば、特許文献１参照）。 This is also called a granular type, in which a ferromagnetic polycrystalline thin film composed of a plurality of magnetic particles having high uniaxial magnetic anisotropy is provided on a medium, and magnetic particles are contained in one bit of recorded information. It is included in multiple numbers. As the recording density increases, the number of magnetic particles contained in one bit decreases, so that the magnetic flux decreases and noise increases. Until now, we have been increasing the density by reducing the size of the magnetic particles, but if the particle size is made smaller than this, the energy to hold magnetic information will be insufficient, and the thermal energy will be about room temperature. The information will be lost. Therefore, the use of a recording material having high magnetic stability has been studied as one method for increasing the density. However, when the stability of the magnetic particles is high, there is a problem that recording with a conventional magnetic head becomes impossible. For this reason, there has also been proposed an optically assisted magnetic recording apparatus that performs recording by temporarily reducing the coercive force of magnetic particles with heat (light) before recording with a magnetic head. Furthermore, in order to achieve higher density, bit patterned media has been proposed in which a magnetic recording layer is separated also in the track longitudinal direction and one magnetic particle is recorded as one bit. This is a structure in which a magnetic layer is physically separated for each magnetic particle, and a magnetic material is evenly arranged as a bit carrier in the track longitudinal direction (see, for example, Patent Document 1).
　そして、本件出願の発明者等は、１つの磁性粒子を１ビットとして記録するビットパターンドメディアとして、基板上に、均等に微小な凹部が表出されている下地層が積層され、上記微小な凹部が表出されている下地層の表面上に、非晶質磁性膜が積層されてなり、上記下地層は、テトラエトキシシランを原材料とし、面心立方構造状に均等に自己配列された球状ミセルが取り除かれることにより、同一サイズの球状の空孔が面心立方体構造状に均等に形成されてなる酸化珪素からなる層であり、上記非晶質磁性膜が積層される面に、均等に微小な凹部が表出されるように表面処理が施されている磁気記録媒体を先に提案している（例えば、特許文献２参照）。 The inventors of the present application, as a bit-patterned medium that records one magnetic particle as one bit, laminates an underlayer on which a minute concave portion is uniformly exposed on a substrate. An amorphous magnetic film is laminated on the surface of the underlayer in which the concave portion is exposed. The underlayer is made of tetraethoxysilane as a raw material, and is spherical in self-alignment evenly in a face-centered cubic structure. By removing the micelles, it is a layer made of silicon oxide in which spherical holes of the same size are uniformly formed in a face-centered cubic structure, and evenly on the surface on which the amorphous magnetic film is laminated A magnetic recording medium that has been surface-treated so that minute concave portions are exposed has been proposed (see, for example, Patent Document 2).
　また、磁気ディスクメモリは、今日のコンピュータ社会を支える重要なファイルメモリシステムであるが、磁性材料の応答速度の物理的限界が近づいており、近い将来、大容量データを適切な速度で記録することが不可能になる。 Magnetic disk memory is an important file memory system that supports today's computer society, but the physical limit of the response speed of magnetic materials is approaching, and large-capacity data will be recorded at an appropriate speed in the near future. Becomes impossible.
　これを打破する新たな手法として、本件出願の発明者等は、円偏光で磁化状態を制御するようにした円偏光による記録方法を提案している（例えば、非特許文献１、特許文献２参照）。 As a new technique for overcoming this problem, the inventors of the present application have proposed a recording method using circularly polarized light in which the magnetization state is controlled by circularly polarized light (see, for example, Non-Patent Document 1 and Patent Document 2). ).
　すなわち、磁化可能な媒体と、前記媒体の磁化を選択的に配向するように、前記磁化可能な媒体の磁気スピン系に対して角運動量を付与するように適合された照射系とを備える光磁気スイッチング素子により、反対の磁化またはスピンの領域として情報「ビット」を記録することができる。 That is, a magneto-optic comprising a magnetizable medium and an irradiation system adapted to impart angular momentum to the magnetic spin system of the magnetizable medium so as to selectively orient the magnetization of the medium The switching element allows information “bits” to be recorded as regions of opposite magnetization or spin.
　磁性材料中のスピン状態は、適切な角運動量の照射を、特に円偏光または楕円偏光を使用して操作することができる。有効磁界は、磁区の磁化を配向するために生成され、同時に材料を局所的に加熱するのに使用することができる。 The spin state in the magnetic material can be manipulated with appropriate angular momentum irradiation, especially using circularly or elliptically polarized light. An effective magnetic field is generated to orient the magnetization of the magnetic domains and can be used to locally heat the material at the same time.
　円偏光レーザーパルスは、有効磁界としてのスピン軌道結合を介してスピンに作用するが、この効果は逆ファラデー効果として知られている。この磁界の大きさは、第一次近似では温度に応じて変わらない磁気光学定数に比例する。したがって、現象論的には、効果全体は、磁気系の加熱に逆ファラデー効果による有効磁界の印加を加えたものである。キュリー温度近傍において拡散する磁化率のため、スイッチングは非常に効率的である。 A circularly polarized laser pulse acts on spins through spin orbit coupling as an effective magnetic field, and this effect is known as an inverse Faraday effect. The magnitude of this magnetic field is proportional to the magneto-optic constant that does not vary with temperature in the first order approximation. Therefore, phenomenologically, the overall effect is the heating of the magnetic system plus the application of an effective magnetic field due to the inverse Faraday effect. Switching is very efficient due to the magnetic susceptibility diffusing near the Curie temperature.
　具体的には、フェムト秒パルスレーザを光源とした円偏光を用い、ＧｄＦｅＣｏ薄膜に対しパルス長４０ｆｓ（フェムト秒：１０－１５秒）の単一パルス照射のみで磁化反転できる。また、その光－スピン間作用が光の進行方向へ磁界を加えたことと等価で、円偏光のヘリシティ（右回りあるいは左回り）の選択により制御可能であり、現象論的に逆ファラデー効果で説明できる。 Specifically, the magnetization can be reversed only by irradiation of a single pulse having a pulse length of 40 fs (femtosecond: 10-15 seconds) to a GdFeCo thin film using circularly polarized light using a femtosecond pulse laser as a light source. The light-spin action is equivalent to the application of a magnetic field in the direction of light travel, and can be controlled by selecting circularly polarized helicity (clockwise or counterclockwise). I can explain.
特開２００９－１６３８１６号公報JP 2009-163816 A ＷＯ２００５／０８１２３３号公報WO2005 / 081233 特表２００９－５３８４９０号公報Special table 2009-538490 gazette
　従来の光磁気記録は、光によって温度が上昇することを利用しており書き込み速度が本質的に遅く、また、書き込み領域が小さくなると磁化が不安定になり情報が消えてしまうという問題点がある。 Conventional magneto-optical recording uses the fact that the temperature rises due to light, so that the writing speed is inherently slow, and when the writing area becomes small, the magnetization becomes unstable and information is lost. .
　本件出願の発明者等が先に提案している円偏光で磁化状態を制御するようにした円偏光による記録方法では、外部磁界無しで円偏光により高速磁化反転させることができるのであるが、現行の技術では、高速記録はできても、記録密度を増加することが難しい。すなわち、高密度記録には、円偏光を局所的に発生する必要があるのにもかかわらず、光の回折限界の物理的制限により波長のオーダーまでしか光を絞ることができない。 In the recording method using circularly polarized light that has been proposed by the inventors of the present application to control the magnetization state with circularly polarized light, high-speed magnetization reversal can be achieved by circularly polarized light without an external magnetic field. With this technique, it is difficult to increase the recording density even though high-speed recording is possible. That is, in high-density recording, although it is necessary to locally generate circularly polarized light, light can be focused only to the order of the wavelength due to the physical limitation of the diffraction limit of light.
　ところで、円偏光でプラズモン共鳴が起こることが報告されており（例えば、非特許文献２参照）、局所的な円偏光を作るのに、近接場光の利用が考えられる。 Incidentally, it has been reported that plasmon resonance occurs in circularly polarized light (see, for example, Non-Patent Document 2), and it is conceivable to use near-field light to create local circularly polarized light.
　本件出願の発明者等は、ナノメートルサイズ十字型開口アンテナ近傍の円偏光解析を行い、記録媒体を配置した状態でナノメートルサイズ十字型開口アンテナ近傍の円偏光に近いモードを形成できることを公表している（例えば、非特許文献３参照）。 The inventors of the present application conducted a circular polarization analysis in the vicinity of the nanometer-size cross-shaped aperture antenna and announced that a mode close to circular polarization near the nanometer-size cross-shaped aperture antenna can be formed with the recording medium disposed. (For example, refer nonpatent literature 3).
　そこで、本発明の目的は、上述の如き従来の実情に鑑み、円偏光による直接磁化反転により情報を記録するに当たり、高速化と高密度化を同時に実現した情報記録ヘッド、情報記録装置及び情報記録方法を提供することにある。 Accordingly, an object of the present invention is to provide an information recording head, an information recording apparatus, and an information recording apparatus that simultaneously realize high speed and high density in recording information by direct magnetization reversal by circularly polarized light in view of the conventional situation as described above. It is to provide a method.
　また、本発明の他の目的は、レーザ光の照射により磁気効果を変化させる機能を有する光デバイス法を提供することにある。 Another object of the present invention is to provide an optical device method having a function of changing a magnetic effect by irradiation with a laser beam.
　本発明では、上述した課題を解決するために、照射される記録光の進行方向を軸とする略回転対称性を持った形状のナノメートルサイズの回転対称性開口と記録媒体粒子との相互作用を利用して上記記録媒体粒子内に局所的に円偏光を発生して直接磁化反転により情報を記録する。 In the present invention, in order to solve the above-mentioned problem, the interaction between the recording medium particles and the nanometer-sized rotationally symmetric opening having a substantially rotational symmetry with the traveling direction of the irradiated recording light as an axis. Is used to generate circularly polarized light locally in the recording medium particles and record information by direct magnetization reversal.
　すなわち、本発明は、記録媒体粒子が分散された記録層を有する記録媒体に情報をレーザ光により情報を記録する情報記録ヘッドであって、上記記録媒体の記録層に分散されている上記録媒体粒子より大きなサイズで照射される記録光の進行方向を軸とする略回転対称性を持った形状のプラズモンアンテナを備え、上記プラズモンアンテナに上記記録光として照射されるレーザ光により励起され、上記プラズモンアンテナに対向して位置される上記記録媒体の記録層に分散されている記録媒体粒子と、上記プラズモンアンテナとの相互作用により、上記記録媒体粒子内に円偏光又は楕円偏光を発生して直接磁化反転により情報を記録することを特徴とする。 That is, the present invention is an information recording head for recording information with a laser beam on a recording medium having a recording layer in which recording medium particles are dispersed, and the upper recording medium dispersed in the recording layer of the recording medium A plasmon antenna having a shape with substantially rotational symmetry about the traveling direction of the recording light irradiated with a size larger than the particle, and excited by the laser light applied as the recording light to the plasmon antenna, Directly magnetized by generating circularly polarized light or elliptically polarized light in the recording medium particles due to the interaction between the recording medium particles dispersed in the recording layer of the recording medium positioned facing the antenna and the plasmon antenna. Information is recorded by inversion.
　本発明に係る情報記録ヘッドにおいて、上記プラズモンアンテナの回転対称性は、４回対称であることが好ましい。 In the information recording head according to the present invention, the rotational symmetry of the plasmon antenna is preferably four-fold symmetry.
　また、本発明は、情報記録装置であって、記録媒体粒子が分散された記録層を有する記録媒体と、上記録媒体粒子より大きなサイズで照射される記録光の進行方向を軸とする略回転対称性を持った形状のプラズモンアンテナと、上記プラズモンアンテナに上記記録光としてレーザ光を照射する光源とを備え、上記プラズモンアンテナに上記記録光として照射されるレーザ光により励起され、上記プラズモンアンテナに対向して位置される上記記録媒体の記録層に分散されている記録媒体粒子と、上記プラズモンアンテナとの相互作用により、上記記録媒体粒子内に円偏光又は楕円偏光を発生して直接磁化反転により情報を記録することを特徴とする。 The present invention also relates to an information recording apparatus, comprising: a recording medium having a recording layer in which recording medium particles are dispersed; and a substantially rotation about an advancing direction of recording light irradiated with a larger size than the upper recording medium particles A plasmon antenna having a symmetrical shape; and a light source for irradiating the plasmon antenna with laser light as the recording light. The plasmon antenna is excited by the laser light irradiated as the recording light, and is applied to the plasmon antenna. Due to the interaction between the recording medium particles dispersed in the recording layer of the recording medium facing each other and the plasmon antenna, circularly or elliptically polarized light is generated in the recording medium particles, and direct magnetization reversal. It is characterized by recording information.
　本発明に係る情報記録装置において、回転対称性は、４回対称であることが好ましい。 In the information recording apparatus according to the present invention, the rotational symmetry is preferably four-fold symmetry.
　また、本発明に係る情報記録装置において、上記光源は、短パルスレーザ光を照射するものとすることができる。 Moreover, in the information recording apparatus according to the present invention, the light source may irradiate a short pulse laser beam.
　また、本発明に係る情報記録装置において、上記記録媒体は、１つの磁性粒子を１ビットとして記録するビット担体が複数配置されたビットパターンドメディアとすることができる。 In the information recording apparatus according to the present invention, the recording medium may be a bit patterned medium in which a plurality of bit carriers for recording one magnetic particle as one bit are arranged.
　さらに、本発明に係る情報記録装置において、上記記録媒体は、絶縁マトリックス中にナノスケールの微小金属粒子を分散させたグラニュラー構造の記録媒体とすることができる。 Furthermore, in the information recording apparatus according to the present invention, the recording medium can be a recording medium having a granular structure in which nanoscale fine metal particles are dispersed in an insulating matrix.
　また、本発明は、記録媒体粒子が分散された記録層を有する記録媒体に情報をレーザ光により記録する情報記録方法であって、上記記録媒体粒子より大きなサイズで照射される記録光の進行方向を軸とする略回転対称性を持った形状のプラズモンアンテナに上記記録光としてレーザ光を照射し、上記プラズモンアンテナに上記記録光として照射されるレーザ光により励起され、上記プラズモンアンテナに対向して位置される上記記録媒体の記録層に分散されている記録媒体粒子と、上記プラズモンアンテナとの相互作用により、上記記録媒体粒子内に円偏光又は楕円偏光を発生して直接磁化反転により情報を記録することを特徴とする。 The present invention also relates to an information recording method for recording information on a recording medium having a recording layer in which recording medium particles are dispersed with a laser beam, the traveling direction of the recording light irradiated with a size larger than the recording medium particles. A laser beam as the recording light is irradiated to a plasmon antenna having a substantially rotational symmetry with the axis as the axis, excited by the laser light irradiated as the recording light to the plasmon antenna, and opposed to the plasmon antenna. Information is recorded by direct magnetization reversal by generating circularly or elliptically polarized light in the recording medium particles by the interaction of the recording medium particles dispersed in the recording layer of the recording medium positioned and the plasmon antenna. It is characterized by doing.
　本発明に係る情報記録方法は、４回対称の上記プラズモンアンテナに上記記録光として短パルスレーザ光を照射するものとすることができる。 The information recording method according to the present invention can irradiate the plasmon antenna having a 4-fold symmetry with a short pulse laser beam as the recording light.
　さらに、本発明は、レーザ光の照射により磁気効果を変化させる機能を有する光デバイスであって、上記レーザ光の照射により磁化方向が可変される磁性粒子部と、上記磁性粒子部に接して配された少なくとも１つの磁性体部と、上記磁性粒子部より大きなサイズで照射されるレーザ光の進行方向を軸とする略回転対称性を持った形状のプラズモンアンテナとを備え、上記プラズモンアンテナに照射されるレーザ光により励起され、上記プラズモンアンテナに対向して位置される上記磁性体部と、上記プラズモンアンテナとの相互作用により、上記磁性体部内に円偏光又は楕円偏光を発生して直接磁化反転により、上記磁性粒子部に接して配された磁性体部の磁気作用を変化させることを特徴とする。 Furthermore, the present invention is an optical device having a function of changing a magnetic effect by laser light irradiation, wherein the magnetic particle part whose magnetization direction is changed by the laser light irradiation is arranged in contact with the magnetic particle part. At least one magnetic body portion and a plasmon antenna having a substantially rotational symmetry with the traveling direction of laser light irradiated in a larger size than the magnetic particle portion as an axis, and irradiating the plasmon antenna Generated by circularly or elliptically polarized light in the magnetic body portion by the interaction between the plasmon antenna and the magnetic body portion which is excited by the laser beam and is positioned opposite to the plasmon antenna. Thus, the magnetic action of the magnetic body portion arranged in contact with the magnetic particle portion is changed.
　本発明に係る光デバイスは、上記磁性粒子部に接して配された２つ磁性体部を備え、上記磁性体部と、上記プラズモンアンテナとの相互作用により、上記磁性体部内に円偏光又は楕円偏光を発生して直接磁化反転により、上記磁性粒子部に接して配された２つの磁性体部間の磁気抵抗を変化させるものとすることができる。 An optical device according to the present invention includes two magnetic body portions arranged in contact with the magnetic particle portion, and circularly polarized light or elliptical light is formed in the magnetic body portion by interaction between the magnetic body portion and the plasmon antenna. It is possible to change the magnetoresistance between two magnetic body portions arranged in contact with the magnetic particle portion by generating polarized light and directly reversing the magnetization.
　本発明によれば、記録媒体粒子より大きなナノメートルサイズで照射される記録光の進行方向を軸とする略回転対称性を持った形状の回転対称性開口を有するプラズモンアンテナに上記記録光として照射されるフェムト秒パルスレーザ光により励起され、上記プラズモンアンテナの回転称性開口に対向して位置される記録媒体の記録層に分散されている記録媒体粒子と、上記プラズモンアンテナの回転対称性開口との相互作用により、上記記録媒体粒子内に円偏光を発生して直接磁化反転により情報を記録することによって、高速化と高密度化を同時に実現することができ、従来は、1ミクロン程度の磁区サイズの記録しか行えなかったが、数十ナノメートルサイズでの記録を可能にできる。 According to the present invention, a plasmon antenna having a rotationally symmetric aperture having a substantially rotational symmetry with the traveling direction of recording light irradiated at a nanometer size larger than the recording medium particles as an axis is irradiated as the recording light. Recording medium particles excited by the femtosecond pulsed laser light and dispersed in the recording layer of the recording medium located opposite the rotational characteristic aperture of the plasmon antenna, and a rotationally symmetric aperture of the plasmon antenna By generating circularly polarized light in the above recording medium particles and directly recording information by magnetization reversal, the high speed and high density can be realized at the same time. Although only size recording could be performed, recording at a size of several tens of nanometers can be made possible.
　すなわち、本発明によれば、円偏光による直接磁化反転により情報を記録するに当たり、記録媒体の記録層に分散されている記録媒体粒子と、プラズモンアンテナの回転対称性開口との相互作用により、上記記録媒体粒子内に円偏光を発生して直接磁化反転により情報を記録することによって、高速化と高密度化を同時に実現した情報記録ヘッド、情報記録装置及び情報記録方法を提供することができる。 That is, according to the present invention, when recording information by direct magnetization reversal by circularly polarized light, the above-described interaction between the recording medium particles dispersed in the recording layer of the recording medium and the rotationally symmetric aperture of the plasmon antenna By generating circularly polarized light in the recording medium particles and recording information by direct magnetization reversal, it is possible to provide an information recording head, an information recording apparatus, and an information recording method that simultaneously realize high speed and high density.
　また、本発明では、プラズモンアンテナに照射されるレーザ光により励起され、上記プラズモンアンテナに対向して位置される磁性体部と、上記プラズモンアンテナとの相互作用により、上記磁性体部内に円偏光又は楕円偏光を発生して直接磁化反転により、上記磁性粒子部に接して配された磁性体部の磁気作用を変化させることができる。本発明の他の目的、本発明によって得られる具体的な利点は、以下に説明される実施の形態の説明から一層明らかにされる In the present invention, the magnetic body portion excited by the laser light applied to the plasmon antenna and positioned opposite to the plasmon antenna and the plasmon antenna interacts with the circularly polarized light in the magnetic body portion. By generating elliptically polarized light and directly reversing the magnetization, the magnetic action of the magnetic body portion arranged in contact with the magnetic particle portion can be changed. Other objects of the present invention and specific advantages obtained by the present invention will become more apparent from the description of embodiments described below.
図１は、本発明を適用した情報記録装置の概略構成を示す斜視図である。FIG. 1 is a perspective view showing a schematic configuration of an information recording apparatus to which the present invention is applied. 図２は、上記情報記録装置の構成の要部構成を模式的に示すブロック図である。FIG. 2 is a block diagram schematically showing the main configuration of the information recording apparatus. 図３Ａ及び図３Ｂは、上記情報記録装置における情報記録ヘッドに備えられるプラズモンヘッドのシミュレーションモデルを示す模式図である。3A and 3B are schematic views showing a simulation model of a plasmon head provided in an information recording head in the information recording apparatus. 図４Ａ～図４Ｄは、回転対称性を有する立体形状の立体アンテナの構造例を模式的に示す図である。4A to 4D are diagrams schematically showing structural examples of a solid antenna having a three-dimensional shape having rotational symmetry. 図５Ａ～Ｄは、４回対称性アンテナの構造例を模式的に示す図である。5A to 5D are diagrams schematically showing an example of the structure of a four-fold symmetry antenna. 図６Ａ～図６Ｄは、２回対称性アンテナの構造例を模式的に示す図である。6A to 6D are diagrams schematically showing an example of the structure of a two-fold symmetry antenna. 図７Ａ及び図７Ｂは、４回対称性開口型アンテナの電磁界の時間分布を示す図である。7A and 7B are diagrams illustrating time distributions of electromagnetic fields of a four-fold symmetrical aperture antenna. 図８Ａ及び図８Ｂは、上記４回対称性開口型アンテナの開口中央の観測点における磁気媒体方向（＋Ｚ方向）のポインチングベクトルＳＺ及びＸ－Ｙ平面内の電界と磁界の位相差θを示す図である。FIGS. 8A and 8B show the pointing vector SZ in the magnetic medium direction (+ Z direction) and the phase difference θ between the electric field and the magnetic field in the XY plane at the observation center at the center of the aperture of the 4-fold symmetrical aperture antenna. FIG. 図９は、十字開口型アンテナ及び円形開口型アンテナにおけるポインチングベクトルのＺ方向成分ＳＺの空間分布を示す図である。FIG. 9 is a diagram illustrating a spatial distribution of the Z-direction component SZ of the pointing vector in the cross aperture antenna and the circular aperture antenna. 図１０Ａ及び図１０Ｂは、Ｃｏ連続記録媒体に十字形状の開口（Cross aperture）を対向させた十字開口型アンテナのシミュレーションモデルを示す模式図である。10A and 10B are schematic diagrams illustrating a simulation model of a cross aperture antenna in which a cross-shaped aperture is opposed to a Co continuous recording medium. 図１１は、上記図１０に示した十字開口型アンテナのシミュレーションモデルＸ－Ｙ面内の電界Ｅと磁界Ｈのなす角θの開口部の長辺の長さＬに対する依存性を示す図である。FIG. 11 is a diagram showing the dependence of the angle θ formed by the electric field E and the magnetic field H in the simulation model XY plane of the cross aperture antenna shown in FIG. 10 on the length L of the long side of the opening. . 図１２Ａ～図１２Ｃは、アンテナ無しの場合、十字開口型アンテナ、円形開口型アンテナのシミュレーションモデルにおけるＣｏ連続記録媒体上での各円偏光度Ｃを評価した結果を示す図である。12A to 12C are diagrams showing the results of evaluating each degree of circular polarization C on a Co continuous recording medium in a simulation model of a cross aperture antenna and a circular aperture antenna when there is no antenna. 図１３は、図１２におけるＡ－Ａ’線、Ａ－Ｂ線、Ａ－Ａ’線上での各円偏光度Ｃを示す図である。FIG. 13 is a diagram showing each degree of circular polarization C on the A-A ′ line, the AB line, and the A-A ′ line in FIG. 12. 図１４Ａ～図１４Ｃは、アンテナ無しの場合、十字開口型アンテナ、円形開口型アンテナのシミュレーションモデルにおけるＣｏ連続記録媒体上での各電界強度Ｉを評価した結果を示す図である。FIGS. 14A to 14C are diagrams showing the results of evaluating each electric field intensity I on a Co continuous recording medium in a simulation model of a cross aperture antenna and a circular aperture antenna when there is no antenna. 図１５は、図１４におけるＡ－Ａ’線、Ａ－Ｂ線、Ａ－Ａ’線上での各電界強度Ｉを示す図である。FIG. 15 is a diagram showing each electric field intensity I on the lines A-A ′, AB, and A-A ′ in FIG. 14. 図１６Ａ～図１６Ｃは、アンテナ無しの場合、十字開口型アンテナ、円形開口型アンテナのシミュレーションモデルにおけるＣｏ連続記録媒体上での各性能指数Ｆを評価した結果を示す図である。FIG. 16A to FIG. 16C are diagrams showing the results of evaluating each performance index F on a Co continuous recording medium in a simulation model of a cross aperture antenna and a circular aperture antenna when there is no antenna. 図１７は、図１６におけるＡ－Ａ’線、Ａ－Ｂ線、Ａ－Ａ’線上での各性能指数Ｆを示す図である。FIG. 17 is a diagram showing each figure of merit F on the A-A ′ line, AB line, and A-A ′ line in FIG. 16. 図１８は、図３に示したプラズモンヘッドにおいて、ビット担体上の観測位置でポインチングベクトルＳ、電界Ｅ、磁界Ｈ及びその位相差θをシミュレーションするシミュレーションモデルを示す図である。FIG. 18 is a diagram showing a simulation model for simulating the pointing vector S, the electric field E, the magnetic field H, and the phase difference θ at the observation position on the bit carrier in the plasmon head shown in FIG. 図１９Ａ～図１９Ｃは、十字開口型アンテナのシミュレーションモデルのＸ－Ｚ面内における円偏光度Ｓ、電界強度Ｉ、及び、性能指数Ｆを示す図である。19A to 19C are diagrams showing the degree of circular polarization S, the electric field strength I, and the figure of merit F in the XZ plane of the simulation model of the cross aperture antenna. 図２０Ａ及び図２０Ｂは、上記十字開口型アンテナのシミュレーションモデルのＸ－Ｚ面内における円偏光度Ｓ、及び、記録媒体方向（＋Ｚ方向）の方向余弦ＳＺ／｜Ｓ｜を示す図である。20A and 20B are diagrams showing the degree of circular polarization S in the XZ plane and the direction cosine SZ / | S | in the recording medium direction (+ Z direction) of the simulation model of the cross aperture antenna. 図２１は、上記十字開口型アンテナのシミュレーションモデルの中心部における記録媒体方向（＋Ｚ方向）の位相差分布及び方向余弦ＳＺ／｜Ｓ｜を示す図である。FIG. 21 is a diagram showing the phase difference distribution in the recording medium direction (+ Z direction) and the direction cosine SZ / | S | at the center of the simulation model of the cross aperture antenna. 図２２Ａ～図２２Ｃは、連続記録媒体に対向させた十字開口型アンテナのシミュレーションモデル及びアンテナ無しのシミュレーションモデルの中心部における記録媒体方向（＋Ｚ方向）の位相差分布及び方向余弦ＳＺ／｜Ｓ｜を示す図である。22A to 22C show the phase difference distribution in the direction of the recording medium (+ Z direction) and the direction cosine SZ / | S | at the center of the simulation model of the cross aperture antenna facing the continuous recording medium and the simulation model without the antenna. FIG. 図２３は、連続記録媒体に対向させた十字開口型アンテナのシミュレーションモデル及びアンテナ無しのシミュレーションモデルの中心部における記録媒体方向（＋Ｚ方向）の位相差分布及び方向余弦ＳＺ／｜Ｓ｜を示す図である。FIG. 23 is a diagram showing a phase difference distribution in the recording medium direction (+ Z direction) and a direction cosine SZ / | S | at the center of a simulation model of a cross aperture antenna facing a continuous recording medium and a simulation model without an antenna. It is. 図２４Ａ及び図２４Ｂは、上記情報記録装置における情報記録ヘッドに備えられるプラズモンヘッドの他のシミュレーションモデルを示す模式図である。24A and 24B are schematic views showing other simulation models of the plasmon head provided in the information recording head in the information recording apparatus. 図２５Ａ～図２５Ｃは、上記プラズモンヘッドの他のシミュレーションモデルのＸ－Ｚ面内における円偏光度Ｓ’、記録媒体方向（＋Ｚ方向）の方向余弦ＳＺ／｜Ｓ｜、及び、電界強度Ｉ’を示す図である。25A to 25C show the degree of circular polarization S ′ in the XZ plane, the direction cosine SZ / | S | in the recording medium direction (+ Z direction), and the electric field intensity I ′ in another simulation model of the plasmon head. FIG. 図２６Ａ～図２６Ｃは、上記プラズモンヘッドの他のシミュレーションモデルにおいて、入射円偏光を逆にした場合のＸ－Ｚ面内における円偏光度Ｓ’、記録媒体方向（＋Ｚ方向）の方向余弦ＳＺ／｜Ｓ｜、及び、電界強度Ｉ’を示す図である。FIG. 26A to FIG. 26C show other simulation models of the above plasmon head in which the circular polarization degree S ′ in the XZ plane when the incident circularly polarized light is reversed and the direction cosine SZ / in the recording medium direction (+ Z direction). It is a figure which shows | S | and electric field strength I '. 図２７Ａ及び図２７Ｂは、本発明を適用した光磁気抵抗効果デバイスの構造例を模式的に示す図である。27A and 27B are diagrams schematically showing an example of the structure of a magneto-resistive effect device to which the present invention is applied.
　以下、本発明の実施の形態について、図面を参照して詳細に説明する。なお、本発明は以下の例に限定されるものではなく、本発明の要旨を逸脱しない範囲で、任意に変更可能であることは言うまでもない。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Needless to say, the present invention is not limited to the following examples, and can be arbitrarily changed without departing from the gist of the present invention.
　本発明は、例えば図１、図２に示すように、磁性体からなるビット担体１５が媒体基板上に複数配置されるビットパターンドメディア１０に情報を記録する情報記録装置１００に適用される。 The present invention is applied to an information recording apparatus 100 that records information on a bit patterned medium 10 in which a plurality of bit carriers 15 made of a magnetic material are arranged on a medium substrate, as shown in FIGS. 1 and 2, for example.
　この情報記録装置１００は、ビットパターンドメディア１０と情報記録ヘッド２０と検出部３０と制御部４０とを備え、上記ビットパターンドメディア１０のビット担体１５の配置位置を検出部３０により直接検出して、その検出信号を記録のクロック信号として用いて制御部４０により記録動作を制御して、情報記録ヘッド２０により上記ビットパターンドメディア１０のビット担体１５に情報を１ビットごとに記録するものである。 The information recording apparatus 100 includes a bit patterned medium 10, an information recording head 20, a detection unit 30, and a control unit 40, and directly detects the arrangement position of the bit carrier 15 of the bit patterned medium 10 by the detection unit 30. Then, the recording operation is controlled by the control unit 40 using the detection signal as a recording clock signal, and information is recorded on the bit carrier 15 of the bit patterned medium 10 by the information recording head 20 bit by bit. is there.
　記録媒体として用いられるビットパターンドメディア１０は、磁性体からなるビット担体（記録担体）１５が基板上に複数配置されている。ビット担体１５は、例えば半導体製造プロセス等により１ビットが１ビット担体に対応するように形成されるものであり、例えば図１の一部拡大図に示されるように、磁性層に凹凸を形成することでビット担体となる磁性領域とそれ以外の領域である非磁性領域に分離されたものである。なお、物理的に凹凸を設けて形成されたビットパターンドメディアに限定されず、１ビット担体となるように構成された媒体であれば、如何なる構造であっても良い。例えば組成や膜構造を変化させて磁気的に分離された媒体等でも構わない。例えば、高分子の自己組織化現象を利用した面心立方構造(Face-Centered Cubic ）配列のナノスケール空孔を内部に有するＳｉＯ２膜を下地層に用い高密度磁性微粒子膜の作製し、この多孔質ＳｉＯ２膜の表面をＡｒイオンエッチングにより周期的に配列したナノメートルサイズの凹凸を表出させたテンプレート基板上に、高充填密度のナノメートルサイズの磁性微粒子を形成した超高密度記録媒体を用いることができる。 In the bit patterned medium 10 used as a recording medium, a plurality of bit carriers (recording carriers) 15 made of a magnetic material are arranged on a substrate. The bit carrier 15 is formed so that one bit corresponds to one bit carrier, for example, by a semiconductor manufacturing process or the like. For example, as shown in a partially enlarged view of FIG. Thus, it is separated into a magnetic region serving as a bit carrier and a nonmagnetic region serving as the other region. It should be noted that the present invention is not limited to the bit patterned medium formed with physical unevenness, and any structure may be used as long as the medium is configured to be a 1-bit carrier. For example, a medium that is magnetically separated by changing the composition or the film structure may be used. For example, a high-density magnetic fine particle film is fabricated by using a SiO2 film with nanoscale vacancies inside a face-centered cubic structure (Face-Centered Cubic 配 列) array using a polymer self-organization phenomenon as an underlayer. An ultra-high-density recording medium in which nanometer-size magnetic fine particles with a high packing density are formed on a template substrate on which nanometer-size irregularities are exposed by periodically arranging the surface of a porous SiO2 film by Ar ion etching is used. be able to.
　情報記録ヘッド２０は、制御部４０により発光タイミングが制御され記録用のレーザ光を出射する半導体レーザを用いた光源部２１と、上記光源部２１から記録光として出射されるレーザ光により励起され、ビットパターンドメディア１０上のビット担体１５内部に円偏光を発生させるナノメートルサイズの開口２２Ａを有するプラズモンアンテナ２２とからなる。 The information recording head 20 is excited by a light source unit 21 using a semiconductor laser that emits a recording laser beam whose emission timing is controlled by the control unit 40, and a laser beam emitted as the recording light from the light source unit 21, It comprises a plasmon antenna 22 having a nanometer-size opening 22A for generating circularly polarized light inside the bit carrier 15 on the bit patterned medium 10.
　上記光源部２１には、記録用のレーザ光として例えば波長λが７８０ｎｍのレーザ光を出射する半導体レーザが用いられる。 上記光源部２１は、制御部４０により発光タイミングが制御され記録用のレーザ光として例えば波長λが７８０ｎｍのフェムト秒パルスレーザ光を出射する。 For the light source unit 21, a semiconductor laser that emits a laser beam having a wavelength λ of 780 nm, for example, is used as a recording laser beam. The light source unit 21 emits a femtosecond pulsed laser beam having a wavelength λ of 780 nm, for example, as a recording laser beam whose emission timing is controlled by the control unit 40.
　検出部３０は、情報記録ヘッド２０によりビット担体１５に記録を行なう前に、そのビット担体１５の配置位置を検出する。即ち、検出部３０は、記録を行おうとするビット担体１５の配置位置を、記録を行う前に予め検出しておく。ビット担体１５は高精度なプロセスにより製造されるが、記録密度を高めるためにビット担体１５の配置ピッチが例えば２５ｎｍピッチというように微細になるにつれ、製造誤差による配置位置のずれの影響が無視できなくなってくる。検出部３０は、このずれを補償するためにビット担体１５の配置位置を検出すべく設けられたものであり、ビット担体１５の配置位置を検出し、これに基づきこの配置位置に応じた相関信号を出力する。 The detecting unit 30 detects the arrangement position of the bit carrier 15 before recording on the bit carrier 15 by the information recording head 20. That is, the detection unit 30 detects the arrangement position of the bit carrier 15 to be recorded before recording. The bit carrier 15 is manufactured by a high-precision process. However, as the arrangement pitch of the bit carrier 15 becomes finer, for example, 25 nm pitch in order to increase the recording density, the influence of the displacement of the arrangement position due to the production error can be ignored. It will disappear. The detection unit 30 is provided to detect the arrangement position of the bit carrier 15 in order to compensate for this deviation, detects the arrangement position of the bit carrier 15, and based on this, the correlation signal corresponding to this arrangement position is detected. Is output.
　なお、ビット担体１５の配置位置を検出する手法は種々のものが利用できる。一例としては、ビット担体１５の配置位置に起因する物理的現象変化を検出するものが挙げられる。物理的現象変化としては、例えばビット担体１５に対する光強度変化、静電容量変化、磁気変化、渦電流変化、音波反射時間変化等が挙げられる。例えば、ビット担体１５に対して光を照射すると、ビット担体１５の配置位置によってその近接場光強度が変化するので、これを検出する。また、静電容量を検出する場合には、ビット担体１５の配置位置によって金属板間の静電容量が変化することを利用する。同様に、磁気の変化を磁気センサで検出したり、金属板に生じる渦電流の変化を検出したり、超音波等を照射して反射波の返ってくる時間を計測することで硬度の変化を検出したりすることで、ビット担体１５の配置位置を検出することができる。 Various methods for detecting the arrangement position of the bit carrier 15 can be used. As an example, there is one that detects a physical phenomenon change caused by the position of the bit carrier 15. Examples of the physical phenomenon change include a light intensity change, a capacitance change, a magnetic change, an eddy current change, and a sound wave reflection time change with respect to the bit carrier 15. For example, when the bit carrier 15 is irradiated with light, the near-field light intensity changes depending on the arrangement position of the bit carrier 15, and this is detected. Further, when detecting the capacitance, the fact that the capacitance between the metal plates changes depending on the arrangement position of the bit carrier 15 is utilized. Similarly, the change in hardness can be detected by detecting the change in magnetism with a magnetic sensor, detecting the change in eddy current generated in the metal plate, or measuring the time when the reflected wave returns by irradiating ultrasonic waves. By detecting it, the arrangement position of the bit carrier 15 can be detected.
　制御部４０は、検出部３０により得られた相関信号を用いて、情報記録ヘッド２０のビット担体１５に対する記録のタイミングを制御する。すなわち、ビット担体１５の位置を検出した上でその配置位置にタイミングを合わせて情報記録ヘッド２０の記録を行う。制御部４０は、情報記録ヘッド２０による記録タイミングを決定するクロック信号を出力するように構成されれば良く、このクロック信号として、ビット担体１５の配置位置の変化に対応する相関信号を用いることで、ビット担体１５の配置位置を検出し、これをクロック信号としてそのまま用いることが可能となる。したがって、例えば４５ｎｍピッチで配置されているべきビット担体１５が、製造誤差により個々のビット担体間の距離が４４ｎｍや４６ｎｍに変化したとしても、上記情報記録ヘッド２０による記録前にこの配置位置の変化を上記検出部４０で検出し、正確にビット担体１５に対してタイミングを合わせて記録を行うことが可能となる。なお、記録媒体の回転速度と情報記録ヘッド・検出部間の距離との関係により、所定のタイミングだけ遅延させたクロック信号を出力して記録を行えば良い。 The control unit 40 controls the recording timing of the information recording head 20 on the bit carrier 15 using the correlation signal obtained by the detection unit 30. That is, after the position of the bit carrier 15 is detected, the information recording head 20 performs recording in accordance with the arrangement position. The control unit 40 only needs to be configured to output a clock signal that determines the recording timing by the information recording head 20, and by using a correlation signal corresponding to a change in the arrangement position of the bit carrier 15 as this clock signal. The arrangement position of the bit carrier 15 can be detected and used as it is as a clock signal. Therefore, for example, even if the bit carrier 15 to be arranged at a pitch of 45 nm changes the distance between the individual bit carriers to 44 nm or 46 nm due to a manufacturing error, the arrangement position changes before recording by the information recording head 20. Can be detected by the detection unit 40, and recording can be accurately performed on the bit carrier 15 at the same timing. Note that recording may be performed by outputting a clock signal delayed by a predetermined timing depending on the relationship between the rotation speed of the recording medium and the distance between the information recording head and the detection unit.
　この情報記録装置１００は、上記光源部２１から出射される波長λが７８０ｎｍのフェムト秒パルスレーザ光を上記ナノメートルサイズの開口２２Ａを有するプラズモンアンテナ２２に照射することにより、上記プラズモンアンテナ２２を励振して、上記プラズモンアンテナ２２とビットパターンドメディア１０上のビット担体１５との相互作用により局所的に円偏光を発生する。これにより、外部磁界無しで上記ビット担体１５を円偏光により直接磁化反転させ、１ビットの情報を記録する。 The information recording apparatus 100 excites the plasmon antenna 22 by irradiating the plasmon antenna 22 having the nanometer size opening 22A with femtosecond pulsed laser light having a wavelength λ of 780 nm emitted from the light source unit 21. Then, circularly polarized light is locally generated by the interaction between the plasmon antenna 22 and the bit carrier 15 on the bit patterned medium 10. As a result, the bit carrier 15 is directly magnetized by circularly polarized light without an external magnetic field, and 1-bit information is recorded.
　なお、上記光源部２１は、情報記録ヘッド２０の外部に設け、上記光源部から出射された波長λが７８０ｎｍのフェムト秒パルスレーザ光を上記プラズモンアンテナ２２に照射する導光路を情報記録ヘッド２０に設けるようにしてもよい。 The light source unit 21 is provided outside the information recording head 20, and a light guide path for irradiating the plasmon antenna 22 with femtosecond pulsed laser light having a wavelength λ of 780 nm emitted from the light source unit is provided to the information recording head 20. You may make it provide.
　上記ビットパターンドメディア１０上のビット担体１５との相互作用により局所的に円偏光を発生するプラズモンアンテナ２２には、光の進行方向を軸とする回転対称性を持った形状のナノメートルサイズの開口２２Ａを有する開口アンテナが用いられる。 The plasmon antenna 22 that generates circularly polarized light locally by interaction with the bit carrier 15 on the bit patterned medium 10 has a nanometer-sized shape having rotational symmetry about the traveling direction of light. An aperture antenna having an aperture 22A is used.
　例えば図３Ａ及び図３Ｂにシミュレーションモデルを示すように、縦・横それぞれ２０００ｎｍの正方形で厚さ３５ｎｍの銀（Ａｇ）製の板２２Ｂに長辺Ｌ＝１５０ｎｍ、短辺Ｗ＝２０ｎｍの長方形を直交させた十字形状の開口（Cross aperture）２２Ａを設けた十字開口型アンテナが上記プラズモンアンテナ２２として用いられる。 For example, as shown in the simulation model in FIGS. 3A and 3B, a rectangular plate having a long side L = 150 nm and a short side W = 20 nm is orthogonally crossed on a silver (Ag) plate 22B having a square of 2000 nm in both vertical and horizontal directions and a thickness of 35 nm. A cross-opening antenna provided with a cross-shaped aperture 22 </ b> A is used as the plasmon antenna 22.
　すなわち、この情報記録装置１００における情報記録ヘッド２０は、記録媒体粒子が分散された記録層を有する記録媒体に情報をフェムト秒パルスレーザ光により情報を記録するものであって、上記記録媒体の記録層に分散されている上記録媒体粒子すなわちビットパターンドメディア１０上のビット担体１５より大きなナノメートルサイズで照射される記録光の進行方向を軸とする回転対称性を持った形状の回転対称性開口２２Ａを有するプラズモンアンテナ２２を備え、上記プラズモンアンテナ２２に上記記録光として照射されるフェムト秒パルスレーザ光により励起され、上記プラズモンアンテナ２２の回転対称性開口２２Ａに対向して位置される上記記録媒体の記録層に分散されている記録媒体粒子と、上記プラズモンアンテナ２２の回転対称性開口２２Ａとの相互作用により、上記記録媒体粒子内に円偏光を発生して直接磁化反転により情報を記録する。 That is, the information recording head 20 in the information recording apparatus 100 records information on a recording medium having a recording layer in which recording medium particles are dispersed by femtosecond pulsed laser light. The rotational symmetry of the shape having rotational symmetry about the traveling direction of the recording light irradiated with the nanometer size larger than the recording medium particles, that is, the bit carrier 15 on the bit patterned medium 10 dispersed in the layer The recording is provided with a plasmon antenna 22 having an opening 22A, and is excited by femtosecond pulsed laser light applied to the plasmon antenna 22 as the recording light, and is positioned facing the rotationally symmetric opening 22A of the plasmon antenna 22. Recording medium particles dispersed in the recording layer of the medium, and the plasmon antenna 2 By interaction with rotational symmetry opening 22A of recording information by direct magnetization reversal by generating a circularly polarized light on the recording medium in the particles.
　ここで、ＦＤＴＤ法（Finite-difference time-domain method; FDTD method）のシミュレーションソフトウエアとして市販の汎用３次元電磁解析ソフトウエアである富士通株式会社製の「Ｐｏｙｎｔｉｎｇ」を用いて開口アンテナ近傍の電磁界シミュレーションを行ったところ、次のような結果が得られた。 Here, the electromagnetic field in the vicinity of the aperture antenna using “Poynting” manufactured by Fujitsu, which is a commercially available general-purpose three-dimensional electromagnetic analysis software as simulation software for the FDTD method (Finite-difference time-domain method; FDTD method). As a result of simulation, the following results were obtained.
　シミュレーションモデルでは、入射光を＋Ｚ軸方向に入射し、波長λ＝７８０ｎｍの円偏光とし、強度分布が中心ピーク電界１Ｖ／ｍのガウシアン分布とし、ガウス半径７８０ｎｍ（Intensity＝１／ｅ２）で、最小セルサイズを１×１×１ｎｍ３とした。 In the simulation model, incident light is incident in the + Z-axis direction, circularly polarized light having a wavelength of λ = 780 nm, a Gaussian distribution with a central peak electric field of 1 V / m, a Gaussian radius of 780 nm (Intensity = 1 / e2), and a minimum. The cell size was 1 × 1 × 1 nm 3.
　ここで、回転対称アンテナには、回転対称性を有する形状の開口アンテナや線状アンテナ、また、例えば、図４Ａ～図４Ｄに示すような回転対称性を有する立体形状の立体アンテナ１１０Ａ，１１０Ｂ、１１０Ｃ，１１０Ｄなどがある。 Here, the rotationally symmetric antenna includes an aperture antenna and a linear antenna having a rotational symmetry, and three- dimensional antennas 110A and 110B having a rotational symmetry as shown in FIGS. 4A to 4D, for example. 110C, 110D, etc.
　４回対称性アンテナは、その構造例を図５Ａ～図５Ｄに示すように、回転対称性を有する形状に形成された開口アンテナや線状アンテナあるいは立体アンテナを２組、４回対称に配置した構造を有する。
　図５Ａに示す４回対称性アンテナ２２１Ａ、金属板に４回対称性を持つ開口を設けた４回対称性開口アンテナである。 As shown in FIGS. 5A to 5D, the four-fold symmetry antenna has two sets of aperture antennas, linear antennas or three-dimensional antennas formed in a shape having rotational symmetry, and is arranged four-fold symmetrically. It has a structure.
FIG. 5A shows a four-fold symmetric antenna 221A, which is a four-fold symmetric aperture antenna in which an opening having four-fold symmetry is provided in a metal plate.
　図５Ｂに示す４回対称性アンテナ２２１Ｂは、線状アンテナを４回対称性を持つように配置した４回対称性線状アンテナである。 A 4-fold symmetrical antenna 221B shown in FIG. 5B is a 4-fold symmetrical linear antenna in which linear antennas are arranged so as to have 4-fold symmetry.
　図５Ｃに示す４回対称性アンテナ２２１Ｃは、回対称性を持つ球状の立体アンテナを４回対称性を持つように配置した４回対称性立体アンテナである。 A 4-fold symmetrical antenna 221C shown in FIG. 5C is a 4-fold symmetrical solid antenna in which spherical solid antennas having a rotational symmetry are arranged so as to have a 4-fold symmetry.
　図５Ｄに示す４回対称性アンテナ２２１Ｄは、回対称性を持つ球状の立体アンテナを４回対称性を持つように配置した４回対称性立体アンテナである。 A 4-fold symmetrical antenna 221D shown in FIG. 5D is a 4-fold symmetrical solid antenna in which spherical three-dimensional antennas having rotational symmetry are arranged so as to have 4-fold symmetry.
　また、２回対称性アンテナは、その構造例を図６Ａ～図６Ｄに示すように、対向する２組の回転対称アンテナのサイズや形状を変化させた構造を有する。 Also, the two-fold symmetry antenna has a structure in which the size and shape of the two pairs of rotationally symmetric antennas facing each other are changed as shown in the structural examples in FIGS. 6A to 6D.
　すなわち、図６Ａに示す２回対称性アンテナ２２２Ａは、金属板に２回対称性を持つように設けたサイズの異なる２組の回転対称開口を有する２回対称性開口アンテナである。 That is, the 2-fold symmetric antenna 222A shown in FIG. 6A is a 2-fold symmetric aperture antenna having two sets of rotationally symmetric apertures of different sizes provided so as to have a 2-fold symmetry in a metal plate.
　図６Ｂに示す２回対称性アンテナ２２２Ｂは、サイズの異なる２組の線状アンテナを２回対称性を持つように配置した２回対称性線状アンテナである。 6B is a two-fold symmetric linear antenna in which two sets of linear antennas having different sizes are arranged so as to have two-fold symmetry.
　図６Ｃに示す２回対称性アンテナ２２２Ｃは、サイズの異なる２組の回対称性を持つ球状の立体アンテナを２回対称性を持つように配置した２回対称性立体アンテナである。 A two-fold symmetric antenna 222C shown in FIG. 6C is a two-fold symmetric three-dimensional antenna in which two sets of spherical three-dimensional antennas with different sizes are arranged so as to have two-fold symmetry.
　図６Ｄに示す２回対称性アンテナ２２２Ｄは、サイズの異なる２組の回対称性を持つ球状の立体アンテナを２回対称性を持つように配置した２回対称性立体アンテナである。 A two-fold symmetric antenna 222D shown in FIG. 6D is a two-fold symmetric three-dimensional antenna in which two sets of spherical three-dimensional antennas having different sizes are arranged so as to have two-fold symmetry.
　これらは、例えば対称軸に４５°程度傾いた方向に電界ベクトルを有する直線偏光を入射する等して、長軸短軸の共鳴条件の違いによる位相差で円偏向を生成することができる。すなわち、上記プラズモンアンテナ２２は、原理的には２回対称性を持つアンテナであれば良い。 These can generate circular deflection with a phase difference due to a difference in resonance conditions of the major axis and the minor axis by, for example, entering linearly polarized light having an electric field vector in a direction inclined by about 45 ° with respect to the symmetry axis. That is, the plasmon antenna 22 may be an antenna having two-fold symmetry in principle.
　４回対称性開口型アンテナでは、長辺Ｌ＝１５０ｎｍ、短辺Ｗ＝２０ｎｍの長方形を直交させた十字形状の開口（Cross aperture）を設けた十字開口型アンテナの電磁界の時間分布を図７Ａ及び図７Ｂに示すように、電界成分はＸ方向成分ＥＸとＹ方向成分ＥＹの大きさが等しく、磁界成分はＸ方向成分ＨＸとＹ方向成分ＨＹの大きさが等しく、電界成分と磁界成分の位相差がλ／４ずれている。 FIG. 7A shows the time distribution of the electromagnetic field of a cross aperture antenna provided with a cross-shaped aperture (Cross aperture) in which a rectangle having a long side L = 150 nm and a short side W = 20 nm is orthogonal. 7B, the electric field component has the same magnitude of the X direction component EX and the Y direction component EY, the magnetic field component has the same magnitude of the X direction component HX and the Y direction component HY, and the electric field component and the magnetic field component have the same magnitude. The phase difference is shifted by λ / 4.
　そして、上記４回対称性開口型アンテナの中央の観測点における磁気媒体方向（＋Ｚ方向）のポインチングベクトルＳＺ及びＸ－Ｙ平面内の電界と磁界の位相差θを図８Ａ及び図８Ｂに示すように、４回対称性開口型アンテナは、ＳＺ／｜Ｓ｜＞０．９５のとき、伝搬方向及び電界と磁界の位相差θ
　θ＝ｔａｎ－１（ＥＸ／ＥＹ）－ｔａｎ－１（ＨＸ／ＨＹ）
　が一定であり、円偏光を発生するプラズモンアンテナとして用いるのに適している。 8A and 8B show the pointing vector SZ in the magnetic medium direction (+ Z direction) and the phase difference θ between the electric field and the magnetic field in the XY plane at the central observation point of the 4-fold symmetrical aperture antenna. Thus, the four-fold symmetric aperture antenna has a propagation direction and a phase difference θ between the electric field and the magnetic field when SZ / | S |> 0.95.
θ = tan-1 (EX / EY) -tan-1 (HX / HY)
Is suitable for use as a plasmon antenna that generates circularly polarized light.
　また、十字開口型アンテナ及び円形開口型アンテナにおけるポインチングベクトルのＺ方向成分ＳＺの空間分布を図９に示すように、十字開口型アンテナでは、局所的に高いエネルギーを伝搬する。 In addition, as shown in FIG. 9, the spatial distribution of the Z-direction component SZ of the pointing vector in the cross aperture antenna and the circular aperture antenna propagates high energy locally.
　そこで、図１０Ａ及び図１０Ｂに示すように、長辺の長さＬ、短辺の長さＷの長方形を直交させた十字形状の開口（Cross aperture）２２Ａ’を銀（Ａｇ）製の板２２Ｂ’に設けた十字開口型アンテナのシミュレーションモデルについて、Ｌ＝１００～４００ｎｍ，Ｗ＝２０ｎｍとし、入射光を＋Ｚ軸方向に入射し、波長λ＝７８０ｎｍの円偏光とし、強度分布が中心ピーク電界１Ｖ／ｍのガウシアン分布とし、Ｃｏ連続記録媒体１５０を媒体とアンテナ間距離ＦＨ＝５ｎｍとして配置したシミュレーションモデルにおいて、記録媒体上１ｎｍの位置でポインチングベクトルＳ、電界Ｅ、磁界Ｈ及びその位相差θを評価し、記録媒体無しの場合と比較した。 Therefore, as shown in FIGS. 10A and 10B, a cross-shaped aperture 22A ′ in which rectangles having a long side length L and a short side length W are orthogonal to each other is formed into a silver (Ag) plate 22B. For the simulation model of the cross aperture antenna provided in ', L = 100 to 400 nm, W = 20 nm, incident light is incident in the + Z axis direction, circularly polarized light having a wavelength λ = 780 nm, and the intensity distribution has a central peak electric field of 1 V / M Gaussian distribution, and in a simulation model in which the Co continuous recording medium 150 is arranged with the distance between the medium and the antenna FH = 5 nm, the pointing vector S, the electric field E, the magnetic field H, and the phase difference θ at a position of 1 nm on the recording medium Was compared with the case without a recording medium.
　円偏光モード解析には、電界Ｅと磁界Ｈが入射円偏光に同期して回転モードになっていることに加えて、ポインチングベクトルＳが安定して記録媒体方向（＋Ｚ軸方向）を向いていることに着目した。 In the circular polarization mode analysis, in addition to the electric field E and the magnetic field H being in the rotation mode in synchronization with the incident circular polarization, the pointing vector S is stably directed to the recording medium direction (+ Z axis direction). Focused on being.
　記録媒体無しの場合、開口部の長辺Ｌが２５０ｎｍ以上においてポインチングベクトルＳの向きが＋Ｚ軸方向と－Ｚ軸方向にランダムに変化する現象が現れた。また、開口部の長辺Ｌが１００ｎｍ～２００ｎｍの範囲では、ポインチングベクトルＳが常に＋Ｚ軸方向を示し、その方向余弦（ＳＺ／｜Ｓ｜）は常に０．９９５以上であった。この時のＸ－Ｙ面内の電界Ｅと磁界Ｈのなす角θの開口部の長辺の長さＬに対する依存性を図１１に示すように記録媒体無しでは、上記角θの長辺Ｌに依存し大きく変化している。 In the case of no recording medium, a phenomenon in which the orientation of the pointing vector S randomly changes in the + Z axis direction and the −Z axis direction when the long side L of the opening is 250 nm or more. In addition, when the long side L of the opening is in the range of 100 nm to 200 nm, the pointing vector S always indicates the + Z-axis direction, and the direction cosine (SZ / | S |) is always 0.995 or more. At this time, the dependence of the angle θ formed by the electric field E and the magnetic field H in the XY plane on the length L of the long side of the opening is shown in FIG. Depends greatly on the change.
　一方、記録媒体を配置した場合には、解析した範囲内で開口部の長辺の長さＬに依らずＸ－Ｙ面内の電界Ｅと磁界Ｈのなす角θは常に９０°から１３０°の範囲を示し、また、その方向余弦（ＳＺ／｜Ｓ｜）は常に０．９９５以上であった。 On the other hand, when the recording medium is arranged, the angle θ formed by the electric field E and the magnetic field H in the XY plane is always 90 ° to 130 ° regardless of the length L of the long side of the opening within the analyzed range. The direction cosine (SZ / | S |) was always 0.995 or more.
　以上のように、記録媒体を配置した状態でナノメートルサイズの十字開口型アンテナ近傍において円偏光に近いモードを形成するができる。 As described above, a mode close to circularly polarized light can be formed in the vicinity of a nanometer-sized cross-open antenna with a recording medium arranged.
　ここで、光の強度を示すパラメータＳＩ、水平優越分を示すパラメータＳＱ、＋４５°優越分を示すパラメータＳＣ、円優越分を示すパラメータＳＳを電場の平均値によって表したストークスパラメータＳＩ、ＳＱ、ＳＣ、ＳＳ
　ＳＩ＝＜ＥＸ２＞＋＜ＥＹ２＞
　ＳＱ＝＜ＥＸ２＞－＜ＥＹ２＞
　ＳＣ＝＜２ＥＸＥＹcosｒ＞
　ＳＳ＝＜２ＥＸＥＹsinｒ＞
　を用いて、表１に示すように、どのような偏光であるか、すなわち、右回り円偏光、直線偏光、４５°ずれた直線偏光、あるいは、楕円偏光であるかを評価することができる。 Here, the parameter SI indicating the light intensity, the parameter SQ indicating the horizontal dominant component, the parameter SC indicating the + 45 ° dominant component, and the Stokes parameter SI, SQ, SC in which the parameter SS indicating the circle dominant component is represented by the average value of the electric field. , SS
SI = <EX2> + <EY2>
SQ = <EX2>-<EY2>
SC = <2EXEY cosr>
SS = <2EXEYsinr>
As shown in Table 1, it is possible to evaluate what the polarization is, that is, clockwise circularly polarized light, linearly polarized light, linearly polarized light shifted by 45 °, or elliptically polarized light.
　ここで、ＥＸは電界のＸ成分、ＥＹは電界のＹ成分、ｒは電界のＸ成分ＥＸとＹ成分ＥＹの位相差、＜＞は時間平均を表す。 Where EX is the X component of the electric field, EY is the Y component of the electric field, r is the phase difference between the X component EX and the Y component EY of the electric field, and <> is the time average.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　アンテナ無しの場合、十字開口型アンテナ、円形開口型アンテナのシミュレーションモデルについて、上記ストークスパラメータＳＩ、ＳＱ、ＳＣ、ＳＳを拡張した次の各式を用いて円偏光度Ｃ、電界強度Ｉ、性能指数Ｆを評価した結果を図１２～図１７に示す。 When there is no antenna, the circular polarization degree C, the electric field strength I, and the figure of merit for the simulation model of the cross aperture antenna and the circular aperture antenna are obtained by using the following equations obtained by extending the Stokes parameters SI, SQ, SC, and SS. The evaluation results of F are shown in FIGS.
　Ｃ＝＜２ＥＸＥＹsinｒ＞／（＜ＥＸ２＞＋＜ＥＹ２＞＋＜ＥＺ２＞）
　Ｉ＝＜ＥＸ２＞＋＜ＥＹ２＞＋＜ＥＺ２＞
　Ｆ＝Ｃ×Ｉ＝＜２ＥＸＥＹsinｒ＞
　　ここで、ＥＸは電界のＸ成分、ＥＹは電界のＹ成分、ＥＺは電界のＺ成分、ｒは電界のＸ成分ＥＸとＹ成分ＥＹの位相差、＜＞は時間平均を表す。 C = <2EXEYsinr> / (<EX2> + <EY2> + <EZ2>)
I = <EX2> + <EY2> + <EZ2>
F = C × I = <2EXEYsinr>
Here, EX is the X component of the electric field, EY is the Y component of the electric field, EZ is the Z component of the electric field, r is the phase difference between the X component EX and the Y component EY of the electric field, and <> is the time average.
　図１２Ａ～図１２Ｃは、アンテナ無しの場合、十字開口型アンテナを設けた場合、円形開口型アンテナを設けた場合におけるＣｏ連続記録媒体２５０上での各円偏光度Ｃを示し、図１３は、図１２Ａ～図１２ＣにおけるＡ－Ａ’線、Ａ－Ｂ線、Ａ－Ａ’線上での各円偏光度Ｃを示している。 12A to 12C show the respective circular polarization degrees C on the Co continuous recording medium 250 when there is no antenna, when a cross aperture antenna is provided, and when a circular aperture antenna is provided, and FIG. 12A to 12C show the respective circular polarization degrees C on the AA ′ line, AB line, and AA ′ line.
　図１４Ａ～図１４Ｃは、アンテナ無しの場合、十字開口型アンテナを設けた場合、円形開口型アンテナを設けた場合におけるＣｏ連続記録媒体２５０上での各電界強度Ｉを示し、図１５は、図１４Ａ～図１４ＣにおけるＡ－Ａ’線、Ａ－Ｂ線、Ａ－Ａ’線上での各電界強度Ｉを示している。 14A to 14C show electric field strengths I on the Co continuous recording medium 250 when there is no antenna, when a cross aperture antenna is provided, and when a circular aperture antenna is provided, and FIG. 14A to 14C show the electric field intensities I on the AA ′ line, AB line, and AA ′ line.
　図１６Ａ～図１６Ｃは、アンテナ無しの場合、十字開口型アンテナを設けた場合、円形開口型アンテナを設けた場合におけるＣｏ連続記録媒体２５０上での各性能指数Ｆを示し、図１７は、図１６Ａ～図１６ＣにおけるＡ－Ａ’線、Ａ－Ｂ線、Ａ－Ａ’線上での各性能指数Ｆを示している。 16A to 16C show performance indexes F on the Co continuous recording medium 250 when there is no antenna, when a cross aperture antenna is provided, and when a circular aperture antenna is provided, and FIG. The figure of merit F on the AA ′ line, AB line, and AA ′ line in FIGS. 16A to 16C is shown.
　しかしながら、十字開口型アンテナや円形開口型アンテナでは、開口の範囲内の領域に高いエネルギーを伝搬することができ、特に、十字開口型アンテナでは、局所的に高いエネルギーを伝搬することができるのであるが、開口のエッジ部分に電界強度Ｉが高くなった領域が形成されてしまい、この開口のエッジ部分の電界強度Ｉが高くなった領域まで記録となってしまう虞がある。 However, with a cross aperture antenna or a circular aperture antenna, high energy can be propagated to a region within the aperture range, and in particular, with a cross aperture antenna, high energy can be propagated locally. However, there is a possibility that a region where the electric field intensity I is high is formed at the edge portion of the opening, and recording is performed up to the region where the electric field intensity I is high at the edge portion of the opening.
　これに対して、上述の如くビットパターンドメディア１０上のビット担体１５内部に円偏光を発生させるナノメートルサイズの開口２２Ａを有するプラズモンアンテナ２２として、上述の図３Ａ及び図３Ｂに示した４回対称性開口型アンテナ、すなわち、長辺の長さＬ、短辺の長さＷの長方形を直交させた十字形状の開口（Cross aperture）２２Ａを銀（Ａｇ）製の板２２Ｂに設けた十字開口型アンテナのシミュレーションモデルについて、Ｌ＝１５０ｎｍ，Ｗ＝２０ｎｍとし、入射光を＋Ｚ軸方向に入射し、波長λ＝７８０ｎｍの円偏光とし、強度分布が中心ピーク電界１Ｖ／ｍのガウシアン分布とし、媒体とアンテナ間距離ＦＨ＝５ｎｍとして配置したシミュレーションモデルにおいて、図１８に示すよう、ビット担体１５上１ｎｍの位置でポインチングベクトルＳ、電界Ｅ、磁界Ｈ及びその位相差θをシミュレーションし、円偏光度Ｃ、電界強度Ｉ、性能指数Ｆを評価した結果を図１９～図２１に示すように、ビット担体１５内部に円偏光を確実に発生することができ、高速、高密度磁気記録を行うことができる。 On the other hand, as described above, the plasmon antenna 22 having the nanometer-size opening 22A for generating circularly polarized light inside the bit carrier 15 on the bit patterned medium 10 is used four times as shown in FIGS. 3A and 3B. Symmetric aperture antenna, that is, a cross aperture in which a cross-shaped aperture 22A in which rectangles having a long side length L and a short side length W are orthogonal to each other is provided in a silver (Ag) plate 22B As for a simulation model of a type antenna, L = 150 nm, W = 20 nm, incident light is incident in the + Z-axis direction, circularly polarized light with a wavelength λ = 780 nm, intensity distribution is a Gaussian distribution with a central peak electric field of 1 V / m, In the simulation model arranged with the antenna distance FH = 5 nm, the position of 1 nm on the bit carrier 15 as shown in FIG. The simulation results of the pointing vector S, the electric field E, the magnetic field H, and the phase difference θ thereof, and the results of evaluating the circular polarization degree C, the electric field strength I, and the figure of merit F are shown in FIGS. Thus, circularly polarized light can be reliably generated, and high-speed and high-density magnetic recording can be performed.
　ここで、図１９Ａ～図１９Ｃは、十字開口型アンテナのシミュレーションモデルのＸ－Ｚ面内における円偏光度Ｓ、電界強度Ｉ及び、性能指数Ｆを示し、また、図２０Ａ及び図２０Ｂは、上記十字開口型アンテナのシミュレーションモデルのＸ－Ｚ面内における円偏光度Ｓ、及び、記録媒体方向（＋Ｚ方向）の方向余弦ＳＺ／｜Ｓ｜を示し、さらに、図２１は、上記十字開口型アンテナのシミュレーションモデルの中心部における記録媒体方向（＋Ｚ方向）の位相差分布及び方向余弦ＳＺ／｜Ｓ｜を示している。 Here, FIGS. 19A to 19C show the degree of circular polarization S, the electric field intensity I, and the figure of merit F in the XZ plane of the simulation model of the cross aperture antenna, and FIGS. 20A and 20B show the above-mentioned FIG. 21 shows the circular polarization degree S in the XZ plane and the direction cosine SZ / | S | in the recording medium direction (+ Z direction) of the simulation model of the cross aperture antenna. 2 shows the phase difference distribution in the recording medium direction (+ Z direction) and the direction cosine SZ / | S | at the center of the simulation model.
　なお、連続記録媒体２５０に対向させた十字開口型アンテナのシミュレーションモデルのＸ－Ｚ面内における円偏光度Ｓ、電界強度Ｉ及び、性能指数Ｆを図２２に示すとともに、連続記録媒体２５０に対向させた十字開口型アンテナのシミュレーションモデル及びアンテナ無しのシミュレーションモデルの中心部における記録媒体方向（＋Ｚ方向）の位相差分布及び方向余弦ＳＺ／｜Ｓ｜を図２３に示す。 Note that the degree of circular polarization S, the electric field intensity I, and the figure of merit F in the XZ plane of the simulation model of the cross aperture antenna facing the continuous recording medium 250 are shown in FIG. FIG. 23 shows the phase difference distribution in the recording medium direction (+ Z direction) and the direction cosine SZ / | S | at the center of the simulation model of the crossed aperture antenna and the simulation model without the antenna.
　図２２、図２３に示すように、連続記録媒体２５０に対向させた十字開口型アンテナのシミュレーションモデル及びアンテナ無しのシミュレーションモデルでは、中心部における記録媒体方向（＋Ｚ方向）の方向余弦ＳＺ／｜Ｓ｜はほぼ一定で、位相差分布が少し変化しているに過ぎないのに対し、ビット担体１５に対向させた十字開口型アンテナのシミュレーションモデルでは、図２１に示すように、ビット担体１５の領域のみ記録媒体方向（＋Ｚ方向）の位相差分布及び方向余弦ＳＺ／｜Ｓ｜が明確に変化している。 As shown in FIGS. 22 and 23, in the simulation model of the cross aperture type antenna facing the continuous recording medium 250 and the simulation model without the antenna, the direction cosine SZ / | S in the direction of the recording medium (+ Z direction) in the center portion. | Is almost constant and the phase difference distribution is only slightly changed. On the other hand, in the simulation model of the cross aperture antenna facing the bit carrier 15, the area of the bit carrier 15 is shown in FIG. Only the phase difference distribution in the recording medium direction (+ Z direction) and the direction cosine SZ / | S | clearly change.
　したがって、上述の如くビットパターンドメディア１０上のビット担体１５に対向するナノメートルサイズの開口２２Ａを有するプラズモンアンテナ２２では、上記ビット担体１５内部に円偏光を確実に発生することができ、高速、高密度磁気記録を行うことができる。 Therefore, in the plasmon antenna 22 having the nanometer-sized opening 22A facing the bit carrier 15 on the bit patterned medium 10 as described above, circularly polarized light can be reliably generated inside the bit carrier 15, and the high speed, High density magnetic recording can be performed.
　すなわち、この情報記録装置１００では、ビットパターンドメディア１０上のビット担体１５より大きなナノメートルサイズで照射される記録光の進行方向を軸とする回転対称性を持った形状の回転対称性開口２２Ａを有するプラズモンアンテナ２２に上記記録光としてフェムト秒パルスレーザ光を照射し、上記プラズモンアンテナ２２に上記記録光として照射されるフェムト秒パルスレーザ光により励起され、上記プラズモンアンテナ２２の回転対称性開口２２Ａに対向して位置される上記ビットパターンドメディア１０上のビット担体１５と、上記プラズモンアンテナ２２の回転対称性開口２２Ａとの相互作用により、上記ビット担体１５内に円偏光を発生して直接磁化反転により情報を記録する。 That is, in the information recording apparatus 100, the rotationally symmetric opening 22A having a rotational symmetry about the traveling direction of the recording light irradiated with a nanometer size larger than the bit carrier 15 on the bit patterned medium 10 is used. Is irradiated with femtosecond pulsed laser light as the recording light, and excited by the femtosecond pulsed laser light irradiated as the recording light onto the plasmon antenna 22, and the rotationally symmetric aperture 22 </ b> A of the plasmon antenna 22. Due to the interaction between the bit carrier 15 on the bit patterned medium 10 and the rotationally symmetric aperture 22A of the plasmon antenna 22 which is located opposite to the circularly polarized light in the bit carrier 15 to generate direct magnetization. Record information by inversion.
　従来は、1ミクロン程度の磁区サイズの記録しか行えなかったが、上記プラズモンアンテナ２２により数十ナノメートルサイズでの記録を行うことができる。 Conventionally, only recording of a magnetic domain size of about 1 micron can be performed, but recording with a size of several tens of nanometers can be performed by the plasmon antenna 22.
　このように、本発明によれば、プラズモンアンテナ２２に形成されたナノメートルサイズの開口２２Ａと記録媒体粒子１５との相互作用を利用して局所的に円偏光を発生して直接磁化反転により情報を記録することによって、高速化と高密度化を同時に実現することができる。 As described above, according to the present invention, circularly polarized light is locally generated by utilizing the interaction between the nanometer-size opening 22A formed in the plasmon antenna 22 and the recording medium particle 15, and information is obtained by direct magnetization reversal. By recording this, it is possible to simultaneously realize high speed and high density.
　なお、以上説明した本発明の実施の形態における情報記録装置１００では、上述の如くビットパターンドメディア１０上のビット担体１５に対向するナノメートルサイズの開口２２Ａを有するプラズモンアンテナ２２として十字型開口アンテナすなわち４回対称性開口アンテナを用いたが、原理的には照射される光の進行方向を軸とする２回対称性を持つアンテナであれば良い。 In the information recording apparatus 100 according to the embodiment of the present invention described above, a cross-shaped aperture antenna is used as the plasmon antenna 22 having the nanometer-size aperture 22A facing the bit carrier 15 on the bit patterned medium 10 as described above. That is, although a 4-fold symmetrical aperture antenna is used, in principle, any antenna having a 2-fold symmetry with the traveling direction of the irradiated light as an axis may be used.
　また、上記プラズモンアンテナ２２に形成されたナノメートルサイズの開口２２Ａと記録媒体粒子１５との相互作用を利用して局所的に楕円偏光を発生して直接磁化反転により情報を記録媒体粒子１５に記録することもでき、上記プラズモンアンテナ２２は、照射される光の進行方向を軸とする略回転対称性を持つ形状を有するものであればよい。 Further, by utilizing the interaction between the nanometer-size opening 22A formed in the plasmon antenna 22 and the recording medium particle 15, elliptically polarized light is locally generated and information is recorded on the recording medium particle 15 by direct magnetization reversal. The plasmon antenna 22 only needs to have a shape having substantially rotational symmetry about the traveling direction of the irradiated light.
　また、上記プラズモンアンテナ２２に照射する光には、短パルスレーザ光を用いることができる。 Further, a short pulse laser beam can be used as the light irradiating the plasmon antenna 22.
　また、情報記録装置１００では、ビットパターンドメディア１０上のビット担体１５に対してナノメートルサイズの開口２２Ａを有するプラズモンアンテナ２２により情報を１ビットごとに記録するようにしたが、絶縁マトリックス中にナノスケールの微小金属粒子を分散させたグラニュラー構造の記録媒体の微小金属粒子に対して上記プラズモンアンテナ２２により情報を記録するようにしてもよい。 In the information recording apparatus 100, information is recorded for each bit by the plasmon antenna 22 having the nanometer size opening 22A with respect to the bit carrier 15 on the bit patterned medium 10, but the information is recorded in the insulating matrix. Information may be recorded by the plasmon antenna 22 on fine metal particles of a granular structure recording medium in which nanoscale fine metal particles are dispersed.
　この場合、上記プラズモンアンテナ２２の開口２２Ａの領域内に存在する上記グラニュラー構造の記録媒体の複数の微小金属粒子のうち、上記プラズモンアンテナ２２のナノメートルサイズの開口２２Ａに照射される波長λが７８０ｎｍのフェムト秒パルスレーザ光により励起され、共鳴した微小金属粒子内に円偏光が発生して情報が記録される。 In this case, among the plurality of fine metal particles of the granular structure recording medium existing in the region of the opening 22A of the plasmon antenna 22, the wavelength λ irradiated to the nanometer-size opening 22A of the plasmon antenna 22 is 780 nm. Excited by the femtosecond pulsed laser beam, circularly polarized light is generated in the resonated fine metal particles, and information is recorded.
　また、上記十字開口型アンテナのシミュレーションモデルの中心部において局所的に電界強度を高めるために、中心に近づくに従って幅を狭めた図２４Ａ及び図２４Ｂに示すような形状の十字開口を有する十字開口型アンテナのシミュレーションモデルについて、ＦＤＴＤ法（Finite-difference time-domain method; FDTD method）のシミュレーションソフトウエアとして市販の汎用３次元電磁解析ソフトウエアである富士通株式会社製の「Ｐｏｙｎｔｉｎｇ」を用いて開口アンテナ近傍の電磁界シミュレーションを行ったところ、次のような結果が得られた。 Further, in order to increase the electric field strength locally at the center of the simulation model of the above-mentioned cross aperture antenna, the cross aperture type having a cross aperture having a shape as shown in FIGS. 24A and 24B narrowed toward the center. As for the simulation model of the antenna, the vicinity of the aperture antenna using “Poynting” manufactured by Fujitsu, which is a commercially available general-purpose three-dimensional electromagnetic analysis software, as simulation software for the FDTD method (Finite-difference time-domain method; FDTD method) When the electromagnetic field simulation was performed, the following results were obtained.
　このシミュレーションモデルでは、入射光を＋Ｚ軸方向に入射し、波長λ＝７８０ｎｍの円偏光とし、強度分布が中心ピーク電界１Ｖ／ｍのガウシアン分布とし、ガウス半径７８０ｎｍ（Intensity＝１／ｅ２）で、最小セルサイズを０．５×０．５×０．５ｎｍ３とし、長辺の長さＬ＝１６０ｎｍ、短辺の最小幅Ｗ１＝２０ｎｍ、最大幅Ｗ２＝６０ｎｍとした開口を直交させた十字形状の開口（Cross aperture）１２２Ａを２０００ｎｍ×２０００ｎｍの正方形の銀（Ａｇ）製の板１２２Ｂに設けた十字開口型アンテナのシミュレーションモデルを、直径１５ｎｍのＣｏ記録媒体粒子１５０を１０ｎｍ離してマトリクス状に配置した記録媒体に対向させた。 In this simulation model, incident light is incident in the + Z-axis direction, circularly polarized light having a wavelength λ = 780 nm, a Gaussian distribution with an intensity distribution of a central peak electric field of 1 V / m, a Gaussian radius of 780 nm (Intensity = 1 / e2), A cross-shaped configuration in which the minimum cell size is 0.5 × 0.5 × 0.5 nm3, the long side length L = 160 nm, the short side minimum width W1 = 20 nm, and the maximum width W2 = 60 nm. A simulation model of a cross aperture antenna in which an aperture 122A is provided on a square silver (Ag) plate 122B of 2000 nm × 2000 nm is arranged in a matrix with Co recording medium particles 150 having a diameter of 15 nm separated by 10 nm. It was made to oppose the recording medium.
　図２５Ａ～図２５Ｃは、上記十字開口型アンテナのシミュレーションモデルのＸ－Ｚ面内における円偏光度Ｓ’、記録媒体方向（＋Ｚ方向）の方向余弦ＳＺ／｜Ｓ｜、及び、電界強度Ｉ’を示す。 25A to 25C show the degree of circular polarization S ′ in the XZ plane, the direction cosine SZ / | S | in the recording medium direction (+ Z direction), and the electric field intensity I ′ in the simulation model of the cross aperture antenna. Indicates.
　また、上記十字開口型アンテナのシミュレーションモデルにおいて、入射円偏光を逆にした場合のＸ－Ｚ面内における円偏光度Ｓ’、記録媒体方向（＋Ｚ方向）の方向余弦ＳＺ／｜Ｓ｜、及び、電界強度Ｉ’を図２６Ａ～図２６Ｃに示す。 In the simulation model of the cross aperture antenna, the circular polarization degree S ′ in the XZ plane when the incident circularly polarized light is reversed, the direction cosine SZ / | S | in the recording medium direction (+ Z direction), and The electric field strength I ′ is shown in FIGS. 26A to 26C.
　この十字開口型アンテナのシミュレーションモデルでは、周辺に位置している記録媒体粒子１５０における電界強度Ｉ’は０．２１［（Ｖ／ｍ）２］であったのに対し、中心に位置する記録媒体粒子１５０における電界強度Ｉ’は０．６［（Ｖ／ｍ）２］であり、上記十字開口型アンテナのシミュレーションモデルの中心部において局所的に電界強度を高めることができる。 In the simulation model of the cross aperture antenna, the electric field intensity I ′ of the recording medium particle 150 located in the periphery was 0.21 [(V / m) 2], whereas the recording medium located in the center. The electric field intensity I ′ in the particle 150 is 0.6 [(V / m) 2], and the electric field intensity can be locally increased in the central portion of the simulation model of the cross aperture antenna.
　なお、以上説明した本発明の実施の形態では、本発明を適用した情報記録ヘッドを備える情報記録装置について説明したが、本発明は上記実施の形態のみに限定されるものではない。 In the embodiment of the present invention described above, the information recording apparatus including the information recording head to which the present invention is applied has been described. However, the present invention is not limited to the above embodiment.
　すなわち、本発明によれば、レーザ光で粒子の磁化方向を可変できるので、磁化方向を可変する磁性体に、他の磁性体を接し、磁性体間の磁気的相互作用の変化を利用したデバイス、例えば、磁気抵抗素子、磁気トランジスタ、磁気スイッチ等をレーザ光の照射により制御可能な光デバイスとすることができる。 That is, according to the present invention, since the magnetization direction of particles can be changed by laser light, a device that utilizes a change in magnetic interaction between magnetic bodies by contacting another magnetic body with a magnetic body that changes the magnetization direction. For example, a magnetoresistive element, a magnetic transistor, a magnetic switch, or the like can be an optical device that can be controlled by laser light irradiation.
　ここで、レーザ光の照射により制御可能な光デバイスとした磁気抵抗素子の構成例を図２７Ａ及び図２７Ｂに示す。 Here, FIG. 27A and FIG. 27B show a configuration example of a magnetoresistive element that is an optical device that can be controlled by laser light irradiation.
　この磁気抵抗素子２００は、レーザ光が照射されることにより磁化方向が可変される円柱磁性粒子部２１０と、この円柱磁性粒子部２１０に接した二つの磁性体部２２１，２２２（これは、磁化方向は上方に固定する）を備え、上記円柱磁性粒子２１０の端部がプラズモンアンテナ２３０の十字開口部２３０Ａの中心に位置している。 The magnetoresistive element 200 includes a cylindrical magnetic particle part 210 whose magnetization direction is changed by being irradiated with laser light, and two magnetic body parts 221 and 222 in contact with the cylindrical magnetic particle part 210 (which are magnetized). The end of the cylindrical magnetic particle 210 is positioned at the center of the cross opening 230A of the plasmon antenna 230.
　すなわち、この磁気抵抗素子２００は、レーザ光の照射により磁気効果を変化させる機能を有する光デバイスであって、上記レーザ光の照射により磁化方向が可変される磁性粒子部２１０と、上記磁性粒子部２１０に接して配された２つの磁性体部２２１，２２２と、上記磁性粒子部２１０より大きなサイズで照射されるレーザ光の進行方向を軸とする略回転対称性を持った形状のプラズモンアンテナ２３０とを備える。 That is, the magnetoresistive element 200 is an optical device having a function of changing a magnetic effect by laser light irradiation, and includes a magnetic particle portion 210 whose magnetization direction is changed by the laser light irradiation, and the magnetic particle portion. Two magnetic body portions 221 and 222 disposed in contact with 210, and a plasmon antenna 230 having a substantially rotational symmetry about the traveling direction of laser light irradiated with a size larger than that of the magnetic particle portion 210. With.
　そして、この磁気抵抗素子２００では、上記プラズモンアンテナ２３０に照射されるレーザ光により励起され、上記プラズモンアンテナ２３０に対向して位置される上記磁性粒子部２１０と、上記プラズモンアンテナ２３０との相互作用により、上記磁性粒子部２１０内に円偏光又は楕円偏光を発生して直接磁化反転により、上記磁性粒子部２１０に接して配された磁性体部２２１，２２２の磁気作用を変化させる。上記レーザ光の照射により、上記円柱磁性粒子部２１０の磁化方向を可変すると、それに接した二つの磁性体部２２１，２２２（これは、磁化方向は上方に固定する）の磁化方向に対して、円柱粒子部２１０の磁化方向が上方に向いているときはＡＢ間の抵抗が小さく、逆方向ではＡＢ間の抵抗が大きい（磁性体によっては、逆の場合もある）。このように、磁化方向が変わることで、外部との磁気的相互作用を可変出来るので、磁化を反転することで機能を発現するあらゆる磁気デバイスの高速動作に本発明の手法を利用できる。 The magnetoresistive element 200 is excited by the laser light applied to the plasmon antenna 230, and interacts with the magnetic particle part 210 positioned opposite the plasmon antenna 230 and the plasmon antenna 230. Then, circularly or elliptically polarized light is generated in the magnetic particle part 210 and the magnetic action of the magnetic body parts 221 and 222 disposed in contact with the magnetic particle part 210 is changed by direct magnetization reversal. When the magnetization direction of the cylindrical magnetic particle part 210 is changed by the irradiation of the laser beam, the magnetization direction of the two magnetic body parts 221 and 222 in contact therewith (the magnetization direction is fixed upward) When the magnetization direction of the cylindrical particle part 210 is directed upward, the resistance between AB is small, and the resistance between AB is large in the reverse direction (there may be the opposite depending on the magnetic material). As described above, since the magnetic interaction with the outside can be varied by changing the magnetization direction, the method of the present invention can be used for high-speed operation of any magnetic device that exhibits a function by reversing the magnetization.

Claims (11)

  1. 記録媒体粒子が分散された記録層を有する記録媒体に情報をレーザ光により記録する情報記録ヘッドであって、
    上記記録媒体の記録層に分散されている上記録媒体粒子より大きなサイズで照射される記録光の進行方向を軸とする略回転対称性を持った形状のプラズモンアンテナを備え、
    　上記プラズモンアンテナに上記記録光として照射されるレーザ光により励起され、上記プラズモンアンテナに対向して位置される上記記録媒体の記録層に分散されている記録媒体粒子と、上記プラズモンアンテナとの相互作用により、上記記録媒体粒子内に円偏光又は楕円偏光を発生して直接磁化反転により情報を記録することを特徴とする情報記録ヘッド。     An information recording head for recording information with a laser beam on a recording medium having a recording layer in which recording medium particles are dispersed,
    A plasmon antenna having a shape with substantially rotational symmetry about the traveling direction of recording light irradiated with a larger size than the upper recording medium particles dispersed in the recording layer of the recording medium;
    The interaction between the plasmon antenna and recording medium particles that are excited by the laser light applied to the plasmon antenna as the recording light and are dispersed in the recording layer of the recording medium that is positioned facing the plasmon antenna Thus, the information recording head is characterized in that circularly or elliptically polarized light is generated in the recording medium particles and information is directly recorded by magnetization reversal.
  2. 上記プラズモンアンテナの回転対称性は、４回対称であることを特徴とする請求項１記載の情報記録ヘッド。 2. The information recording head according to claim 1, wherein the rotational symmetry of the plasmon antenna is four-fold symmetric.
  3. 記録媒体粒子が分散された記録層を有する記録媒体と、
    　上記録媒体粒子より大きなサイズで照射される記録光の進行方向を軸とする略回転対称性を持った形状のプラズモンアンテナと、
    　上記プラズモンアンテナに上記記録光としてレーザ光を照射する光源とを備え、
    　上記プラズモンアンテナに上記記録光として照射されるレーザ光により励起され、
    　上記プラズモンアンテナに対向して位置される上記記録媒体の記録層に分散されている記録媒体粒子と、上記プラズモンアンテナとの相互作用により、上記記録媒体粒子内に円偏光又は楕円偏光を発生して直接磁化反転により情報を記録することを特徴とする情報記録装置。     A recording medium having a recording layer in which recording medium particles are dispersed;
    A plasmon antenna having a substantially rotational symmetry about the traveling direction of the recording light irradiated with a size larger than the upper recording medium particles;
    A light source that emits laser light as the recording light to the plasmon antenna;
    Excited by the laser light applied as the recording light to the plasmon antenna,
    Due to the interaction between the recording medium particles dispersed in the recording layer of the recording medium positioned facing the plasmon antenna and the plasmon antenna, circularly or elliptically polarized light is generated in the recording medium particles. An information recording apparatus for recording information by direct magnetization reversal.
  4. 上記プラズモンアンテナの回転対称性は、４回対称であることを特徴とする請求項３記載の情報記録装置。 4. The information recording apparatus according to claim 3, wherein the rotational symmetry of the plasmon antenna is four-fold symmetric.
  5. 上記光源は、短パルスレーザ光を照射することを特徴とする請求項３記載の情報記録装置。 4. The information recording apparatus according to claim 3, wherein the light source irradiates a short pulse laser beam.
  6. 上記記録媒体は、１つの磁性粒子を１ビットとして記録するビット担体が複数配置されたビットパターンドメディアであることを特徴とする請求項３記載の情報記録装置。 4. The information recording apparatus according to claim 3, wherein the recording medium is a bit patterned medium in which a plurality of bit carriers for recording one magnetic particle as one bit are arranged.
  7. 上記記録媒体は、絶縁マトリックス中にナノスケールの微小金属粒子を分散させたグラニュラー構造の記録媒体であることを特徴とする請求項３記載の情報記録装置。 4. The information recording apparatus according to claim 3, wherein the recording medium is a granular structure recording medium in which nanoscale fine metal particles are dispersed in an insulating matrix.
  8. 記録媒体粒子が分散された記録層を有する記録媒体に情報をレーザ光により記録する情報記録方法であって、
    　上記記録媒体粒子より大きなサイズで照射される記録光の進行方向を軸とする回転対称性を持った形状のプラズモンアンテナに上記記録光としてレーザ光を照射し、
    　上記プラズモンアンテナに上記記録光として照射されるレーザ光により励起され、上記プラズモンアンテナに対向して位置される上記記録媒体の記録層に分散されている記録媒体粒子と、上記プラズモンアンテナとの相互作用により、上記記録媒体粒子内に円偏光又は楕円偏光を発生して直接磁化反転により情報を記録することを特徴とする情報記録方法。     An information recording method for recording information with a laser beam on a recording medium having a recording layer in which recording medium particles are dispersed,
    Irradiating a laser beam as the recording light onto a plasmon antenna having a rotational symmetry about the traveling direction of the recording light irradiated with a size larger than the recording medium particles,
    The interaction between the plasmon antenna and recording medium particles that are excited by the laser light applied to the plasmon antenna as the recording light and are dispersed in the recording layer of the recording medium that is positioned facing the plasmon antenna Thus, information is recorded by generating circularly-polarized light or elliptically-polarized light in the recording medium particles, and recording information by direct magnetization reversal.
  9. ４回対称の上記プラズモンアンテナに上記記録光として短パルスレーザ光を照射することを特徴とする請求項８記載の情報記録方法。 9. The information recording method according to claim 8, wherein a short pulse laser beam is irradiated as the recording light onto the plasmon antenna having a four-fold symmetry.
  10. レーザ光の照射により磁気効果を変化させる機能を有する光デバイスであって、
    　上記レーザ光の照射により磁化方向が可変される磁性粒子部と、
    　上記磁性粒子部に接して配された少なくとも１つの磁性体部と、
    　上記磁性粒子部より大きなサイズで照射されるレーザ光の進行方向を軸とする略回転対称性を持った形状のプラズモンアンテナと
    　を備え、
    　　上記プラズモンアンテナに照射されるレーザ光により励起され、上記プラズモンアンテナに対向して位置される上記磁性粒子部と、上記プラズモンアンテナとの相互作用により、上記磁性粒子部内に円偏光又は楕円偏光を発生して直接磁化反転により、上記磁性粒子部に接して配された磁性体部の磁気作用を変化させることを特徴とする光デバイス。     An optical device having a function of changing a magnetic effect by laser light irradiation,
    A magnetic particle portion whose magnetization direction is changed by irradiation with the laser beam;
    At least one magnetic body portion disposed in contact with the magnetic particle portion;
    A plasmon antenna having a substantially rotational symmetry with the traveling direction of laser light irradiated with a size larger than the magnetic particle portion as an axis, and
    Generates circularly or elliptically polarized light in the magnetic particle part by the interaction between the plasmon antenna and the magnetic particle part that is excited by the laser light irradiated to the plasmon antenna and is opposed to the plasmon antenna. An optical device characterized in that the magnetic action of the magnetic part arranged in contact with the magnetic particle part is changed by direct magnetization reversal.
  11. 上記磁性粒子部に接して配された２つ磁性体部を備え、
    　上記磁性粒子部と、上記プラズモンアンテナとの相互作用により、上記磁性粒子部内に円偏光又は楕円偏光を発生して直接磁化反転により、上記磁性粒子部に接して配された２つの磁性体部間の磁気抵抗を変化させることを特徴とする請求項１０記載の光デバイス。     Comprising two magnetic parts arranged in contact with the magnetic particle part,
    Due to the interaction between the magnetic particle part and the plasmon antenna, circularly polarized light or elliptically polarized light is generated in the magnetic particle part, and direct magnetization reversal between two magnetic material parts arranged in contact with the magnetic particle part The optical device according to claim 10, wherein the magnetoresistance of the optical device is changed.
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JP2009060057A (en) * 2007-09-03 2009-03-19 Osaka Univ Optical assist type magnetic recorder

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2522322A (en) * 2013-12-13 2015-07-22 HGST Netherlands BV All-optical magnetic recording system using FeMnPt media
GB2522322B (en) * 2013-12-13 2016-10-19 HGST Netherlands BV All-optical magnetic recording system using FeMnPt media

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