JP2006172715A - Recording and reproducing head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording and reproducing head in which minute magnetic particles successfully exist in a stable manner, and information subjected to fine recording can be reproduced at a high S/N ratio, even when a surface recording density is increased by using the minute magnetic particles to serve as a recording unit. <P>SOLUTION: The recording and reproducing head comprises a magnetic field-generating source for applying a recording magnetic field to a magnetic recording medium; a magnetic element for reading magnetization information on the magnetic recording medium, the magnetic element being selected from a group consisting of a magnetic resistance element, a magnetic element including a spin-valve film, and an induction type magnetic element; and an air slider which carries the magnetic field-generating source and the magnetic element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a magnetic recording medium using a magnetic film having perpendicular magnetization as a recording layer, a recording / reproducing head thereof, and a magnetic recording / reproducing method, and more particularly, to prevent or suppress data loss due to a thermomagnetic relaxation phenomenon. The present invention relates to a magnetic recording medium capable of recording / reproducing at a surface recording density of ²⁰ Gbits / in ² or more, a recording / reproducing head suitable for recording / reproducing, and a novel magnetic recording / reproducing method using them.

  Hard disks (magnetic recording media) are widely used as external storage media such as computers. A hard disk usually employs longitudinal magnetic recording in which information is recorded in parallel with the recording film surface using a ring-shaped magnetic head (hereinafter referred to as a ring head) mounted on a floating slider.

In recent years, the diversification of data such as graphic data, moving image data, and document data has progressed, and the amount of information handled has become enormous. In order to be able to handle such enormous data, increasing the surface recording density is one of the most important technical issues in the field of hard disks. At the present time, the hard disk achieves a surface recording density of ⁴ Gbits / in ² .

  By the way, as one means for increasing the density, for example, in IEEE Transactions on Magnetics, Vol.MAG-15, No.6, pp.1456-1458 (1979), a Co—Cr film having perpendicular magnetization is used as a recording film. There have been proposed a perpendicular magnetic recording system and a perpendicular magnetic recording medium for recording information in a direction perpendicular to the recording film surface.

In order to further increase the surface recording density of a hard disk, it is known that a magnet (magnetic particle) as a recording unit constituting the recording layer may be made smaller. However, if the magnetic particles are miniaturized to have a surface recording density of 10 to 20 Gbits / in ² or more, there is a problem that the magnetic particles become unstable due to the thermomagnetic relaxation phenomenon and recorded data is lost.

  The present invention has been made to solve the problems of the prior art, and its purpose is to make the fine particles stably exist even if the magnetic particles as a recording unit are miniaturized to increase the surface recording density. It is an object of the present invention to provide a magnetic recording medium capable of reproducing minutely recorded information with a high S / N ratio.

  Another object of the present invention is to provide a recording / reproducing head suitable for recording / reproducing information using such a magnetic recording medium.

  Still another object of the present invention is to provide a novel magnetic recording capable of recording information at an ultra-high density using such a magnetic recording medium and a recording / reproducing head and reproducing the recorded information at a high S / N ratio. It is to provide a reproduction method.

According to a first aspect of the present invention, there is provided a magnetic recording medium,
A substrate;
A record-holding layer composed of a magnetic material;
A recording layer made of a ferrimagnetic material having perpendicular magnetization;
Information is recorded by reversing the recording magnetic domain of the recording layer by applying a recording magnetic field while heating a predetermined area of the magnetic recording medium, and information is reproduced by detecting the magnetic field from the recording magnetic domain of the recording layer A magnetic recording medium is provided.

  The magnetic recording medium of the present invention includes a recording layer formed of a ferrimagnetic material having perpendicular magnetization and a recording holding layer formed of a magnetic material. The recording holding layer can be made of, for example, a ferrimagnetic material or an antiferromagnetic material, and is preferably provided between the substrate and the recording layer. In particular, the recording holding layer is preferably provided so as to be in contact with the recording layer. By providing in this way, the recording holding layer can exchange-couple with the recording magnetic domain of the recording layer and can hold the recording magnetic domain in a stable state in the vertical direction. As the ferrimagnetic material that can be used for the recording holding layer, for example, rare earth-transition metal alloys such as TbFeCo, GdTbFeCo, TbFeCoCr, TbFe, GdFeCo, GdTbFe, or DyTbFe are preferable. Antiferromagnetic materials that can be used for the recording holding layer include transition metal (Cr, Mn, Fe, Co, Ni) alloys, noble metals (Au, Pt, Rh, Pd) and transition metals (Cr, Mn, Fe, Co, Ni), transition metal oxides, and the like are preferable. For example, FeMn, NiO, NiMn, PtMn, FeNiMn, AuMn, ZnZr, and FeRh are preferable.

  In the magnetic recording medium of the present invention, in order to ensure the thermal stability of the recording magnetic domain of the recording layer, the temperature is within the temperature range from room temperature (about 10 ° C.), which is the storage temperature of the medium, to the internal temperature (about 100 ° C.) The recording layer needs to have a coercive force of 5 kOe or more. Therefore, the recording layer preferably has a coercive force of 5 kOe or more within a temperature range of 10 ° C to 150 ° C. However, this is not the case when a reproducing layer for increasing the magnetic field from the recording layer as described later is used. Further, when reproducing information recorded on the recording layer, a magnetic field generated from the recording magnetic domain of the recording layer is detected, so it is advantageous to use a recording layer having a high Curie temperature. Therefore, the recording layer preferably has a Curie temperature of 300 ° C. or higher in order to obtain a sufficient magnetic field strength from the recording magnetic domain in the vicinity of the reproduction temperature during reproduction.

  As described above, by using a recording layer having a large coercive force within a temperature range of 10 ° C. to 150 ° C., even if a minute recording mark is formed on the recording layer, the recording mark disappears due to a thermomagnetic relaxation phenomenon after recording. Is suppressed. In recording, the magnetic recording medium can be heated to 200 ° C. or more to reduce the coercive force of the recording layer, so that recording can be easily performed with a weak applied magnetic field. In order to reproduce the recorded information, the magnetic field from the recording magnetic domain of the recording layer is directly detected by, for example, a magnetoresistive element to reproduce the information. That is, the magnetic recording medium of the present invention is different from a magneto-optical recording medium that detects a magnetization state using a magneto-optical effect (for example, the Kerr effect).

  In the magnetic recording medium of the present invention, a reproducing layer can be further provided on the recording layer. The reproducing layer preferably has a saturation magnetization larger than the saturation magnetization of the recording layer in a temperature range of room temperature or higher, preferably 20 ° C. to 150 ° C. That is, since the reproducing layer can generate a larger leakage magnetic field than the recording layer, an amplified reproduced signal can be obtained by detecting the magnetization state of the reproducing layer by transferring the magnetization of the recording layer to the reproducing layer. Can do. The reproducing layer may be an in-plane magnetization film or a perpendicular magnetization film.

  The magnetic recording medium of the present invention can further include a recording auxiliary layer exhibiting soft magnetism. As a material constituting the recording auxiliary layer, for example, permalloy (NiFe), Fe— (Al, Si) alloy, NiFe— (Mo, Cr, Cu, Mn, Rh), and Co-based amorphous alloy can be used. . The recording auxiliary layer is preferably formed so that a magnetic field is applied through the recording layer. That is, when a magnetic field is applied from the substrate side, a structure including a substrate, a recording layer, and a recording auxiliary layer can be provided in this order. When a magnetic field is applied from the side opposite to the substrate, the substrate, the recording layer A structure including an auxiliary layer and a recording layer in this order can be employed. Further, if the recording layer and the recording auxiliary layer are laminated in the above order, an arbitrary layer may be interposed between these layers.

  Furthermore, in the present invention, an arbitrary layer can be provided in addition to the recording auxiliary layer and the recording holding layer. For example, if the recording layer and the recording holding layer are exchange-coupled to each other at the time of recording, it becomes difficult to perform recording corresponding to the recording data. Therefore, the temperature when a predetermined area of the medium is heated at the time of recording (hereinafter referred to as the recording temperature) It is preferable to provide a recording control layer for cutting the exchange coupling between the two layers in the embodiment described later in the vicinity of the Curie temperature of the recording layer. In order to break the exchange coupling at the recording temperature, the Curie temperature of the recording control layer may be set below the Curie temperature of the recording layer. Moreover, it is also possible to form, for example, a homblin-based or silicon-based lubricating layer on the surface of the magnetic recording medium. By providing the lubricating layer, the recording / reproducing head can be smoothly slid on the surface of the medium even when the recording / reproducing head comes into contact with the magnetic recording medium at the time of recording / reproducing. Can be reduced.

  The magnetic recording medium of the present invention can be provided with a texture on the surface of the substrate. By providing a texture on the surface of the substrate, the flying height of the flying head when the flying head is floated on the medium can be controlled to be constant.

According to a second aspect of the present invention, in a recording method for recording information on a magnetic recording medium having a recording layer on a substrate,
Information is recorded by applying a magnetic field in which at least one of intensity and direction is modulated according to information to be recorded, while applying heat to a predetermined area of the magnetic recording medium,
The recording layer is configured using a ferrimagnetic material having perpendicular magnetization,
A magnetic recording medium recording method is provided, wherein a magnetic pole width in a direction perpendicular to the recording direction of the magnetic head is 1 μm or less.

  In the recording method of the present invention, for example, laser light can be used to heat a predetermined area of the magnetic recording medium, and heating is performed by condensing the laser light onto a predetermined area of the medium with an objective lens and irradiating it. can do. Thereby, it is possible to form a minute recording magnetic domain by reducing the coercive force of the recording layer only in the predetermined high temperature region where the laser beam is condensed and reversing the magnetization only in that range. In order to guide the laser beam to the objective lens, it is preferable to use an optical fiber. The optical fiber can efficiently guide laser light from a laser light source to the objective lens in terms of energy. As another method of heating a predetermined area of the magnetic recording medium, a heater such as a coil type heater can be used, and the area at a position of 1 μm or less from the surface of the magnetic recording medium is heated by radiant heat from the heater. Can do.

  In the recording method of the present invention, for example, a series of information can be divided and recorded simultaneously at a plurality of positions on a magnetic recording medium using a plurality of recording magnetic heads. As a result, the information transfer rate can be improved.

According to a third aspect of the present invention, in a reproducing method for reproducing information recorded on a magnetic recording medium having a recording layer,
The recording layer is made of a ferrimagnetic material having perpendicular magnetization,
Reproducing information recorded on a recording layer using a kind of magnetic element selected from the group consisting of a magnetoresistive element, a magnetic element having a spin valve film, and an inductive magnetic element A method is provided.

  In the reproducing method of the present invention, the recorded information is applied to, for example, a magnetoresistive element, a magnetic element having a spin valve film, or an induction type magnetic element (induction type magnetic head) while applying heat to a predetermined area of the magnetic recording medium. Use to play. The magnetic recording medium may be heated at the time of information reproduction. For example, the magnetic recording medium can be heated by irradiating laser light or applying radiant heat from a heater or the like. At the time of recording, recording can be performed by applying a magnetic field in which at least one of intensity and direction is modulated according to recording information while applying heat to a predetermined area of the magnetic recording medium. Further, a series of information respectively recorded at a plurality of positions on the magnetic recording medium can be simultaneously reproduced using, for example, a plurality of magnetic heads equipped with any of the magnetic elements described above.

According to a fourth aspect of the present invention, in a method for recording information on an information recording medium comprising a recording layer having perpendicular magnetization on a substrate,
What is claimed is: 1. A recording method for an information recording medium, wherein information is recorded by irradiating the information recording medium with a light spot and applying a magnetic field only to a region located inside the light spot and smaller than the light spot. Provided.

  In the recording method of the present invention, while irradiating the information recording medium with a light spot, for example, by applying a magnetic field using a single magnetic pole head capable of perpendicular magnetic recording, the area inside the light spot is more than the light spot. A small recording mark is formed. This enables ultra-high density recording. In order to form a recording mark that is smaller than the light spot, the tip portion where the magnetic field lines of the single pole head are generated may be processed by, for example, FIB (focused ion beam) so as to be smaller than the light spot diameter.

According to the fifth aspect of the present invention, in a recording and / or reproducing head of a magnetic recording medium,
A magnetic field source for applying a recording magnetic field to the magnetic recording medium;
A magnetic element for reading magnetization information of a magnetic recording medium, and a kind of magnetic element selected from the group consisting of a magnetoresistive element, a magnetic element having a spin valve film, and an inductive magnetic element;
And a recording and / or reproducing head comprising: an air slider on which the magnetic field generation source and the magnetic element are mounted.

  The head of the present invention can further include a heat source for heating the magnetic recording medium. As the heat source, for example, a laser light source can be used, and a predetermined area of the medium can be heated by condensing and irradiating the laser light emitted from the laser light source onto the medium with an objective lens or the like. In order to guide the laser light to the objective lens, for example, an optical fiber can be used. In addition, it is desirable that the heat source is provided so as to be disposed in front of the magnetic element in the direction of movement relative to the magnetic recording medium. In the present specification, when a recording area of a recording medium moves in a direction (medium moving direction) with respect to an object (for example, a heat source or a head), the object is first recorded on the basis of the object. The side that reaches the recording area is referred to as “front side in the medium movement direction”, and the side that reaches the recording area of the recording medium later is referred to as “rear side in the medium movement direction”.

  In the head of the present invention, the magnetic field generating source for applying the recording magnetic field to the magnetic recording medium can be configured using a single magnetic pole head 220 as shown in FIG. 20, for example. The single magnetic pole head 220 is mainly composed of a core (main magnetic pole) 225, a main body part 221, and a coil 224 wound around the connecting part 223. A protective film may be formed on the inner wall of the core 225. The core 225 is formed by, for example, FIB (focused ion beam) so that the width of the tip of the core in the track width direction of the magnetic recording medium is 1 μm or less when facing the magnetic recording medium having a plurality of tracks. It is preferable that it is processed. As a result, information can be recorded on the magnetic recording medium at an extremely high density. In addition, the magnetic field generating part or the whole of the single magnetic pole head is generated from the single magnetic pole head by using a material having a saturation magnetic flux density (Bs) of 2.0 T or more, such as CoNiFe or CoNiFe alloy system. The magnetic force can be increased, and recording on a recording medium having a high coercive force is possible.

  In the head of the present invention, the magnetoresistive element is an element (MR element: Magneto-Resistive Device) whose electric resistance changes in accordance with the change of the magnetic field, and is perpendicular to the magnetization state of the recording layer and other magnetic layers. The magnetization state in the direction or in-plane direction can be detected. For example, the material of the MR element may be FeMn / CoNi / Cu / Co. Further, a magnetic element having a spin valve film or a magnetic element such as an induction type magnetic head can be used. The spin valve film can be formed of, for example, CoFe / Cu / CoFe / Ru / CoFe / MnPt. In addition, a GMR (Giant Magneto-Resistive) element having a larger rate of change in electrical resistance with respect to a change in magnetic field than an MR element can be used in place of the magnetoresistive element.

  In the present invention, the air slider is preferably configured using a plurality of materials having different thermal conductivities. In particular, it is desirable to use a material having the lowest thermal conductivity among a plurality of materials having different thermal conductivities between the magnetic field generation source and the magnetoresistive element. This prevents the magnetoresistive element from being heated by the heat generated by the magnetic field generation source. Also, heat generated in the magnetic field source can be dissipated to the outside of the head by forming the material with the highest thermal conductivity among a plurality of materials having different thermal conductivities on the portion that comes into contact with the outside air, for example, the upper surface of the head. Can do.

  Hereinafter, a magnetic recording medium, a recording / reproducing head thereof, and a magnetic recording / reproducing method of the present invention will be specifically described with reference to the drawings.

Example 1
FIG. 1 is a schematic cross-sectional view of a specific example of a magnetic recording medium according to the present invention. The magnetic recording medium 100 is formed by sequentially laminating a recording auxiliary layer 2, a recording holding layer 3, a recording control layer 4, a recording layer 5, a protective layer 6 and a lubricant layer 7 on a substrate 1.

  In FIG. 1, a substrate 1 is made of glass and has a diameter of 90 mm and a thickness of 1.2 mm. The substrate 1 may be provided with a texture for stabilizing the flying height of the head. The recording auxiliary layer 2 on the substrate 1 is a soft magnetic film and is made of NiFe (permalloy) having a high magnetic permeability. The Curie temperature Tc6 of NiFe was 500 ° C., and the coercive force Hc6 was 0.1 Oe or less within the temperature range from room temperature to the Curie temperature Tc6.

  As the recording retention layer 3, an antiferromagnetic material FeMn exhibiting perpendicular magnetic anisotropy was used, and its composition was adjusted so that the Curie temperature Tc3 was 450 ° C. The recording control layer 4 was formed using an amorphous ferrimagnetic material DyFeCo exhibiting perpendicular magnetic anisotropy, and its composition was adjusted so that the Curie temperature Tc2 was 200 ° C. DyFeCo constituting the recording control layer 4 exhibits a rare earth dominant (RE-rich) polarity from room temperature to the Curie temperature Tc2.

  The recording layer 5 is made of an amorphous ferrimagnetic material TbFeCo exhibiting perpendicular magnetic anisotropy, and has a coercive force Hc of room temperature to 100 ° C. as shown in the magnetic characteristic graph of FIG. The composition was adjusted so that it was 5 kOe or more within the range, 2 kOe or less within the temperature range of 200 ° C. to 300 ° C., the Curie temperature Tc was 300 ° C., and the compensation temperature was around room temperature. The protective layer 6 is configured using a nonmagnetic material SiN.

  These layers 2 to 6 were sequentially formed by sputtering using a sputtering apparatus. The film thicknesses of the respective layers were: recording auxiliary layer 2: 500 nm, recording holding layer 3: 30 nm, recording control layer 4: 10 nm, recording layer 5: 100 nm, and protective layer 6: 10 nm.

  Next, the lubricant layer 7 was applied to the surface of the protective film 6 by spin coating with a film thickness of 2 nm. For the lubricant layer 7, a heptane solution mainly composed of dimethyl silicone added with modified silicone and fatty acid was used. Thus, the magnetic recording medium 100 having the structure shown in FIG. 1 was manufactured.

  FIG. 2 shows a specific example of a recording / reproducing head according to the present invention. The recording / reproducing head 200 includes a head body 20 and a heat source 31 for heating the magnetic recording medium. The head main body 20 includes an air slider 21, a recording magnetic head 22 and a reproducing MR head 23 mounted on the air slider 21. The air slider 21 is configured using a ceramic material. By using the air slider 21, the head main body 20 can be floated from the medium surface at a predetermined interval. In this embodiment, the head main body 20 is designed to float at a height of 50 nm from the surface of the magnetic recording medium 100 during recording and reproduction.

  The recording magnetic head 22 is a single-pole head that can apply a magnetic field in a direction perpendicular to the surface of the magnetic recording medium 100, and includes a magnetic coil 24 and an iron core 25. The iron core 25 is made of NiFe having a high high-frequency magnetic permeability, and has a cylindrical shape extending in the vertical direction (vertical direction in FIG. 2) of the head main body 20. The tip of the iron core 25 on the side facing the magnetic recording medium 100 is processed by FIB (focused ion beam) so that the width in the direction orthogonal to the track direction (track width direction) is 1 μm or less. The magnetic coil 24 is made of copper wire and is provided so as to go around the outer periphery of the iron core 25. By using the recording magnetic head 22 having such a structure to generate a magnetic field modulated in accordance with recording data, a minute recording mark can be formed on the magnetic recording medium 100. The recording magnetic head 22 can generate a magnetic field of up to 500 Oe. In addition, a magnetic field of 1000 Oe or more may be generated by configuring the tip of the single magnetic pole head using a material having a saturation magnetic flux density (Bs) of 2.0 T or more made of, for example, CoNiFe or an alloy system containing CoNiFe. It becomes possible.

  The reproducing MR head 23 is an MR head for perpendicular magnetization reproduction capable of detecting the perpendicular magnetization state, and the configuration of the MR element is FeMn / CoNi / Cu / Co. The reproducing MR head 23 is provided behind (in the left direction in FIG. 2) the recording magnetic head 22 in the traveling direction of the magnetic recording medium 100 indicated by an arrow in FIG. Data perpendicularly recorded on the layer can be read out. Further, by using a magnetic element having a spin valve film such as CoFe / Cu / CoFe / Ru / CoFe / MnPt instead of the MR element, the magnetic field sensitivity can be further improved.

  In the head main body 20, heat radiation materials 26a and 26b are provided between the reproducing MR head 23 and the recording magnetic head 22 and on the upper surface of the head main body, respectively. Both the heat dissipating materials 26a and 26b are made of Al having high thermal conductivity. These heat dissipating materials 26a and 26b can dissipate the heat generated in the magnetic coil 24 to the outside of the head main body, thereby preventing the reproducing MR head 23 from being heated.

  The heat source 31 mainly includes a laser light source 27, an objective lens 28, and an optical fiber 29, and is provided at a position facing the head main body 20 with the magnetic recording medium interposed therebetween. The laser light source 27 is a semiconductor laser having an oscillation wavelength of 640 nm. The NA (Numerical Aperture) of the objective lens 28 is 0.6. The laser light emitted from the laser light source 27 is guided to the objective lens 28 by the optical fiber 29, is incident on the magnetic recording medium from the substrate side, and is condensed on a predetermined region of the recording layer.

Recording / Reproducing Experiment Using the magnetic recording medium 100 and the recording / reproducing head 200, a recording / reproducing experiment was performed. FIG. 4A shows a conceptual diagram of the arrangement of a magnetic recording medium and a recording / reproducing head in a recording / reproducing experiment, and FIG. 4B shows a cross-sectional view thereof. In the recording / reproducing experiment, as shown in FIG. 4A, the magnetic recording medium 100 is installed with a spindle 102 inserted into a central opening (not shown). The recording / reproducing head 200 is disposed on the lubricant layer side (the side opposite to the substrate) of the magnetic recording medium 100. Although not shown in the drawing, an objective lens for condensing the laser beam on the magnetic recording medium 100 is disposed at a position facing the recording / reproducing head 200 with the magnetic recording medium 100 interposed therebetween, so that the laser beam is emitted from the objective lens. The light is collected and incident from the substrate side of the magnetic recording medium.

  Here, a recording principle when data is recorded on the magnetic recording medium 100 will be described. First, while rotating the magnetic recording medium 100 at a predetermined linear velocity, a laser beam is focused and irradiated on a predetermined area of the magnetic recording medium 100 from the substrate side. FIG. 5A shows a state in which the magnetic recording medium 100 is irradiated with a laser beam condensed from the substrate side (lower side in the drawing). In FIG. 5A, it is assumed that the magnetic recording medium 100 moves to the left. As shown in the temperature distribution graph of FIG. 5A, the power of the laser light is such that the maximum temperature Tmax (maximum value of the temperature showing the Gaussian distribution) of the region irradiated with the light spot 41 is the recording holding layer 3. Among the regions irradiated with the light spot 41 and below the Curie temperature Tc3 (450 ° C.), the temperature of the region including the region 42 to which the external magnetic field is applied (hereinafter referred to as the magnetic field application region) is The temperature is adjusted to be equal to or higher than the Curie temperature Tc (300 ° C.). Simultaneously with the laser light irradiation, an external magnetic field Hex is applied vertically upward with respect to the surface of the magnetic recording medium using the recording magnetic head 22 (single pole head). At this time, the magnetic field application region 42 of the recording layer is smaller than the light spot 41.

  In FIG. 5A, when the magnetic recording medium 100 moves to the left with respect to the light spot, the magnetic field application region 42 is separated from the light spot and cooled. FIG. 5B shows how the magnetization of each magnetic layer changes during the cooling process of the magnetic field application region 42. In the cooling process, when the temperature T of the magnetic field application region 42 is (1) Tc2 (Curie temperature of the recording control layer: 200 ° C.) <T <Tc (300 ° C.), the magnetization of the magnetic field application region of the recording layer is an external magnetic field. Appears in the Hex direction (upward in the figure) as TM-rich (transition metal dominant). (2) When room temperature <T <Tc2 (200 ° C.), the magnetization of the recording control layer appears in the same direction as the magnetization of the recording layer by exchange coupling, and at the same time, the recording layer by exchange coupling with the magnetization of the recording holding layer Is firmly fixed in the vertical direction. Also, the recording auxiliary layer exhibiting soft magnetism allows the magnetic flux (external magnetic field) generated from the tip of the core of the recording magnetic head 22 (single pole head) to pass through the recording layer while being converged. In this way, information is recorded on the recording layer at an extremely high density.

The above is the recording principle of the magnetic recording medium 100 having the laminated structure shown in FIG. Data was recorded on the magnetic recording medium 100 under the following conditions. While rotating the magnetic recording medium 100 at a linear velocity of 1.0 m / s, an external magnetic field is applied to the magnetic recording medium 100 with a magnetic field intensity of 300 Oe modulated at 6.25 MHz using the recording / reproducing head 200, and at the same time, laser power An 8 mW laser beam was irradiated from the substrate side. Thus, recording was performed with a track pitch (TP) of 0.4 μm and a bit pitch (BP) of 0.08 μm. This corresponds to a surface recording density of 20.1 Gbits / in ² and a data transfer rate of 12.5 Mbits / s.

  For the magnetic recording medium 100 on which recording was performed as described above, the magnetization state (recording data) of the recording layer was detected using the recording / reproducing head 200, and the S / N ratio was measured. Next, in order to examine the environmental durability of the magnetic recording medium, the magnetic recording medium was left for a predetermined time in the environment of the following three conditions while maintaining the recording data, and then the S / N ratio was measured again. Here, environment (1) 60 ° C./90% RH, environment (2) 70 ° C./90% RH, environment (3) 80 ° C./90% RH. The graph of FIG. 6 shows how the S / N ratio of the magnetic recording medium changes in each environment. In the graph of FIG. 6, the vertical axis indicates the S / N ratio (relative S / N) as a relative value obtained by normalizing the S / N ratio measured after being left in the above-described environment by the S / N ratio measured before leaving. Ratio). From the graph of FIG. 6, it can be seen that even the harshest environment (3) retains a relative S / N ratio of 95% or more even after 10,000 hours.

Next, the durability of the S / N ratio in an environment of 80 ° C. and 90% RH was investigated for a conventional magnetic recording medium using a CoCr-based magnetic material exhibiting perpendicular magnetization as the recording layer and the magnetic recording medium of the present invention. It was. First, magnetic recording was performed on a conventional magnetic recording medium using a conventional ring head at TP = 1.6 μm and BP = 0.2 μm ( ² Gbits / in ² ) (longitudinal recording), and recording was performed using the MR head. The information was reproduced and the S / N ratio was measured. Next, after leaving for a predetermined time in the above environment (80 ° C., 90% RH), the S / N ratio was measured again using the MR head. Next, recording is performed on the magnetic recording medium 100 of the present invention using the recording / reproducing head 200 of the present invention at TP = 1.6 μm and BP = 0.2 μm ( ² Gbits / in ² ). The recording / reproducing head 200 was used for reproduction and the S / N ratio was measured. Subsequently, after being left for a predetermined time in the above environment (80 ° C. and 90% RH), the S / N ratio was measured again using the recording / reproducing head 200 of the present invention. The graph of FIG. 7 shows changes in the S / N ratio of the conventional magnetic recording medium and the magnetic recording medium of the present invention. In the graph of FIG. 7, the vertical axis indicates the S / N ratio (relative S) as a relative value obtained by normalizing the S / N ratio measured after leaving in the above environment by the S / N ratio measured before leaving. / N ratio). As can be seen from the graph of FIG. 7, in the conventional magnetic recording medium, the relative S / N ratio is remarkably reduced in an environment of 80 ° C. and 90% RH after 1 hour. It had fallen to. On the other hand, the magnetic recording medium of the present invention maintains a high relative S / N ratio even after 5 hours. From this, it can be seen that the magnetic recording medium of the present invention has higher environmental durability than the conventional magnetic recording medium.

  Next, the dependency of the reproduction output on the recording mark length was examined for the magnetic recording medium 100 according to the present invention and the conventional magnetic recording medium. Regarding the recording mark dependency, the magnetic recording medium 100 of the present invention is recorded with various recording mark lengths using the head according to the present invention, and is reproduced using a giant magnetoresistive (GMR) head. Was done. On the other hand, with respect to a conventional magnetic recording medium, recording was performed using a conventional ring head (longitudinal recording), and reproduction was performed using a GMR head. In both the magnetic recording medium of the present invention and the conventional magnetic recording medium, the track pitch was 1.6 μm, and the GMR head having a shield interval of 0.2 μm was used. The graph of FIG. 8 shows how the reproduction output changes with respect to the recording mark length of the magnetic recording medium of the present invention and the conventional magnetic recording medium. In the graph of FIG. 8, the vertical axis indicates the reproduction output normalized by the reproduction signal amplitude when a recording mark having a recording mark length of 1.0 μm is reproduced on a conventional magnetic recording medium. As can be seen from the graph of FIG. 8, the magnetic recording medium of the present invention obtains a higher reproduction output than the conventional magnetic recording medium when the recording mark length is narrowed to 0.2 μm or less.

Example 2
FIG. 9 shows a schematic cross-sectional view of a specific example of a magnetic recording medium according to the present invention, which is different from the first embodiment. The magnetic recording medium 300 is a magnetic recording medium in which a reproducing layer 8 is provided between the recording layer 5 and the protective layer 6 of the magnetic recording medium 100 shown in FIG. The layer 3, the recording control layer 4, the recording layer 5, the reproducing layer 8, the protective layer 6, and the lubricant layer 7 are sequentially laminated. In the magnetic recording medium 300 having such a structure, the material constituting the recording control layer 4 is changed to amorphous ferrimagnetic TbFeCo, the thickness of the recording layer 5 is changed to 50 nm, and the reproducing layer 8 is 20 nm on the recording layer 5. The film was manufactured in the same manner as in Example 1 except that the film was formed with a thickness of.

  In FIG. 9, the recording control layer 4 is composed of an amorphous ferrimagnetic film TbFeCo exhibiting perpendicular magnetic anisotropy, and the composition is adjusted so that its Curie temperature Tc2 becomes 200.degree. The recording control layer 4 exhibits a rare earth dominant (RE-rich) polarity from room temperature to the Curie temperature Tc2.

The reproducing layer 8 is composed of an amorphous ferrimagnetic film GdFeCo, and its Curie temperature Tc4 is 350 ° C. and the compensation temperature Tcomp4 is below room temperature. From room temperature to the Curie temperature, transition metal dominant (TM-rich) perpendicular magnetic anisotropy is exhibited, and the coercive force Hc4 is 500.
Oe or less. Further, the saturation magnetization Ms of the reproducing layer 8 is larger than the saturation magnetization Ms of the recording layer 5 at room temperature or higher as shown in FIG.

Recording / Reproducing Experiment A recording / reproducing experiment was performed in the same manner as in Example 1 except that the magnetic recording medium 100 was changed to the magnetic recording medium 300 manufactured in the present example in the recording / reproducing experiment described in Example 1.

  Here, the recording principle of the magnetic recording medium 300 will be described. First, while rotating the magnetic recording medium 300 at a predetermined linear velocity, a laser beam is focused and irradiated on a predetermined area of the magnetic recording medium 300 from the substrate side. FIG. 11A shows a state in which laser light is condensed and irradiated on the magnetic recording medium 300 from the substrate side (lower side in the figure). In FIG. 11A, it is assumed that the magnetic recording medium 300 moves to the left. As shown in the temperature distribution graph of FIG. 11A, the laser power is such that the maximum temperature Tmax (maximum value of the temperature showing the Gaussian distribution) of the region irradiated with the light spot 41 is the Curie of the recording holding layer 3. Of the region irradiated with the light spot 41 at a temperature Tc3 (450 ° C.) or lower, the temperature of the region including the magnetic field application region 42 was adjusted to be equal to or higher than the Curie temperature Tc4 (350 ° C.) of the reproducing layer 8. Simultaneously with the laser light irradiation, an external magnetic field Hex is applied vertically upward with respect to the surface of the magnetic recording medium 300 using the recording magnetic head 22 (single pole head). At this time, the magnetic field application region 42 is smaller than the light spot 41.

  In FIG. 11A, since the magnetic recording medium 300 moves to the left with respect to the light spot, the magnetic field application region 42 is separated from the light spot and cooled. FIG. 11B shows how the magnetization of each magnetic layer changes during the cooling process of the magnetic field application region 42. In the cooling process of the magnetic field application region 42, when the temperature T of the magnetic field application region 42 becomes (1) Tc (300 ° C.) <T <Tc 4 (350 ° C.), the magnetization of the magnetic field application region of the reproduction layer becomes the external magnetic field Hex. Appears TM-rich in the direction (upward in FIG. 11). (2) When Tc2 (200 ° C.) <T <Tc (300 ° C.), the magnetization of the recording layer located immediately below the magnetic field application region of the reproducing layer is the direction of the external magnetic field Hex (upward in FIG. 11B). Appears in TM-rich. (3) When room temperature <T <Tc2 (200 ° C.), the magnetization of the recording control layer located immediately below the recording layer appears in the same direction as the magnetization of the recording layer by exchange coupling with the recording layer, and at the same time recording The magnetization state of the recording layer is firmly fixed by exchange coupling with the magnetization of the holding layer. According to such a recording principle, information is recorded on the recording layer at an extremely high density. In the above recording process, the magnetic flux (external magnetic field) generated from the tip of the core of the recording magnetic head 22 (single pole head) passes through the recording layer while being converged by the recording auxiliary layer showing soft magnetism. To do.

  In order to reproduce information recorded at an extremely high density, the magnetization state of the reproducing layer is detected using the reproducing MR head 23 mounted on the recording / reproducing head 200. As described above, since the saturation magnetization of the reproducing layer is larger than the saturation magnetization of the recording layer at room temperature, the leakage magnetic field to the reproducing MR head 23 becomes large. Therefore, the sensitivity is improved and the amplitude of the reproduction waveform is increased as compared with the case where the magnetization state of the recording layer is reproduced directly using the reproducing MR head 23 as in the first embodiment. Furthermore, as shown in the graph of FIG. 10, since the saturation magnetization of the reproducing layer increases as the temperature rises from room temperature, the reproducing waveform amplitude can be further increased by heating the magnetic recording medium with low laser power during reproduction. Can do. The above is the reproduction principle of the magnetic recording medium 300 having the laminated structure shown in FIG.

Next, data was recorded on the magnetic recording medium 300 under the following conditions. The magnetic recording medium 300 is rotated at a linear velocity of 1.0 m / s, the recording magnetic head is modulated at an intensity of 300 Oe at 6.25 MHz, and at the same time, an 8 mW laser beam is irradiated to a track pitch (TP) of 0.4 μm. Recording was performed at a bit pitch (BP) of 0.08 μm. This corresponds to a surface recording density of 20.1 Gbits / in ² and a data transfer rate of 12.5 Mbits / s.

  Using the reproducing MR head 22 for the magnetic recording medium 300 recorded with TP = 0.4 μm and BP = 0.08 μm as described above, the following two reproduction conditions (a) When laser light is not irradiated (B) When the laser beam with a laser power of 1.4 mW was irradiated, information was reproduced and the S / N ratio was measured. As a result, the S / N ratio was larger in the reproduction condition (b) than in the reproduction condition (a).

Example 3
FIG. 12 shows a schematic cross-sectional view of another specific example of the magnetic recording medium according to the present invention. The magnetic recording medium 400 is formed by sequentially laminating a recording holding layer 3, a recording control layer 4, a recording layer 5, a reproducing layer 50, a protective layer 6 and a lubricant layer 7 on a substrate 1. The magnetic recording medium 400 having such a structure does not form the recording auxiliary layer 2 on the substrate 1 in Example 1, but forms a reproducing layer 50 having the characteristics described later on the recording layer 5 with a film thickness of 20 nm. The recording control layer 4 was manufactured using amorphous ferrimagnetic TbFeCo having magnetic characteristics described later, and was manufactured in the same manner as in Example 1 except that the film thickness of the recording holding layer 3 was changed to 50 nm.

  In FIG. 12, the recording control layer 4 is composed of an amorphous ferrimagnetic film TbFeCo exhibiting perpendicular magnetic anisotropy, and its composition is adjusted so that the Curie temperature Tc2 is 200 ° C. The recording control layer 4 exhibits a rare earth dominant (RE-rich) polarity from room temperature to the Curie temperature. The reproducing layer 50 is configured using an amorphous ferrimagnetic film GdFeCo having a Curie temperature Tc4 of 280 ° C., and has a composition such that in-plane magnetization is exhibited from room temperature to 150 ° C., and perpendicular magnetization is exhibited at 150 ° C. or more. It was adjusted. The critical temperature at which the stable magnetization direction changes from in-plane to perpendicular is called the perpendicularization temperature and is represented by Tcr4.

  FIG. 13 shows a schematic diagram of a specific example of a recording / reproducing head according to the present invention, which is different from the first embodiment. The recording / reproducing head 210 includes a head main body 120 and a laser light source 127 for heating the medium. The laser light source 127 is a semiconductor laser having an oscillation wavelength of 640 nm. The head main body 120 includes an air slider 121, a recording magnetic head (magnetic coil) 122 mounted on the air slider 121, and a reproducing MR head 123. The air slider 121 is configured using a ceramic material (or transparent glass). By using the air slider 121, the head main body 120 can be floated from the medium surface at a predetermined interval. In this embodiment, the head main body 120 is designed to float at a height of 50 nm from the surface of the medium during recording and reproduction.

  In FIG. 13, a recording magnetic head 122 is a single-pole head that can apply a magnetic field in a direction perpendicular to the medium surface, and includes a magnetic coil 108 and an annular core portion 105. The core portion 105 is configured using a ferromagnetic material NiFe having a high frequency magnetic permeability. As shown in FIG. 13, the outer periphery of the core portion 105 is fitted so as to be joined to the inner periphery of the through hole 130 formed from the upper surface to the lower surface of the slider. The magnetic coil 108 is made of a copper wire, and is provided below the core portion 105 so as to go around the outer periphery of the core portion 105. Using such a recording magnetic head 122, data can be recorded on the medium by generating an external magnetic field modulated in accordance with the recording data. The recording magnetic head 122 can generate a magnetic field of 500 Oe at the maximum.

  In FIG. 13, an objective lens 109 for condensing laser light on the medium is inserted inside the annular core portion 105. The NA (Numerical Aperture) of the objective lens 109 is 0.85. The objective lens 109 collects the laser light incident from the upper opening 105a of the core 105 and irradiates the medium from the lower opening 105b of the core 105 toward the medium.

  The reproducing MR head 123 is an MR head for perpendicular magnetization reproduction capable of detecting the perpendicular magnetization state, and the configuration of the MR element is FeMn / CoNi / Cu / Co. The reproducing MR head is provided behind (in the left direction in FIG. 13) the recording magnetic head in the direction of movement relative to the magnetic recording medium, and is perpendicular to the recording layer of the magnetic recording medium. The recorded data can be read out.

  In the head main body 120, a heat blocking layer 126 a is formed between the reproducing MR head 123 and the recording magnetic head 122. The heat blocking layer 126 a is configured using a ceramic having low thermal conductivity, and reduces the influence of heat generated by the magnetic coil 108 on the reproducing MR head 123. Further, a heat dissipating material 126b made of Al having high thermal conductivity is formed on the upper surface of the head main body, and heat generated from the magnetic coil 108 can be dissipated outside the head.

Recording and Reproduction of Information Recording and reproduction can be performed using the magnetic recording medium 400 and the recording / reproducing head 210. Recording and reproduction are performed by loading the magnetic recording medium 400 in an evaluation device (drive) and placing the recording / reproducing head 210 on the lubricant layer side (opposite side of the substrate) of the magnetic recording medium 400.

  Here, the recording and reproducing principles of the magnetic recording medium 400 will be described with reference to FIGS. FIG. 14A shows a state in which a predetermined region of the magnetic recording medium 400 is irradiated with a laser beam condensed from the lubricant layer side (the upper side in the drawing). The magnetic recording medium 400 is rotated at a predetermined linear velocity, and the magnetic recording medium is moved in the left direction in FIG. As shown in the temperature distribution graph of FIG. 14A, the laser beam power is such that the maximum temperature Tmax (maximum value of the temperature showing the Gaussian distribution) of the region irradiated with the light spot 41 is The Curie temperature Tc3 (450 ° C.) or less is adjusted so that the temperature of a part of the region irradiated with the light spot 41 is equal to or higher than the Curie temperature Tc4 (280 ° C.) of the reproducing layer 8. At the same time as irradiating the magnetic recording medium 400 with laser light, an external magnetic field Hex is applied vertically upward with respect to the surface of the magnetic recording medium 400 using the recording magnetic head 122 (single pole head).

  In FIG. 14A, when the magnetic recording medium 400 moves to the left with respect to the light spot, a region heated by the light spot irradiation (hereinafter referred to as a high temperature region) is removed from the light spot and cooled. FIG. 14B shows how the magnetization of each magnetic layer changes during the cooling process in the high temperature region. When the temperature in the high temperature region is represented by T, as shown in FIG. 14B, (1) Tc4 (Curie temperature of the reproduction layer: 280 ° C.) <T <Tc (Curie temperature of the recording layer: 300 ° C.) Then, the magnetization in the high temperature region of the recording layer appears TM-rich in the direction of the external magnetic field Hex (upward). (2) When Tc2 (200 ° C.) <T <Tc4 (280 ° C.), the magnetization of the reproducing layer located immediately above the recording layer is downward in RE-rich due to exchange coupling with the magnetization of the recording layer. Lattice magnetization appears upward). (3) When Tcr4 (150 ° C.) <T <Tc 2 (200 ° C.), the magnetization of the recording control layer appears in the same direction as the magnetization of the recording region of the recording layer by exchange coupling with the magnetization of the high temperature region of the recording layer. At the same time, the magnetization state of the recording layer is firmly fixed by exchange coupling with the magnetization of the recording holding layer. (4) At room temperature <T <Tcr4 (150 ° C.), the magnetization of the reproducing layer is directed from the perpendicular direction to the in-plane direction. Information is thus recorded on the recording layer. The above is the principle of recording.

  Next, the principle of reproduction will be described. In order to reproduce the information recorded according to the recording principle described above, the magnetic recording medium 400 is heated by irradiating a reproducing laser beam having a low laser power while rotating the magnetic recording medium 400 at a predetermined linear velocity. FIG. 15 shows a state in which the reproduction laser beam 150 is irradiated to a predetermined area of the magnetic recording medium 400. By irradiating the reproducing laser beam 150 to the magnetic recording medium 400, the surface of the magnetic recording medium 400 is heated with a temperature distribution as shown in the lower graph of FIG. In the region above the perpendicularization temperature Tcr4 of the reproducing layer, the magnetization changes from the in-plane direction to the vertical direction. At this time, the magnetization state of the recording layer located immediately below the reproducing layer is transferred to the reproducing layer by the exchange coupling force. As shown in FIG. 15, the reproducing MR head 123 is located immediately above the boundary where the magnetization of the reproducing layer changes from in-plane magnetization to perpendicular magnetization. Further, since the size of the reproducing MR head 123 is larger than the size of the magnetic domain of the reproducing layer, a plurality of reproducing layer magnetizations 151 and 152 exist in the region immediately below the reproducing MR head 123. However, since the magnetization 152 of the reproducing layer located on the left side of the reproducing MR head 123 is directed in the in-plane direction, it is not detected by the reproducing MR head 123, and one vertical magnetization 151, ie, reproducing Only the magnetization information of the recording layer existing immediately below the magnetization of the layer is extracted independently. Further, the in-plane magnetization 152 of the reproducing layer is not affected by the magnetization state of the recording layer located immediately below it. Further, since the saturation magnetization of the reproducing layer is larger than the saturation magnetization of the recording layer as shown in FIG. 10 and increases as the temperature rises, the reproducing laser beam is irradiated as described above to generate a magnetic field. By heating the recording medium, the reproducing MR head 123 can detect a large leakage magnetic field from the reproducing layer. The above is the principle of reproduction of the magnetic recording medium 400.

Example 4
FIG. 16 shows a schematic cross-sectional view of a specific example of the magnetic recording medium of the present invention, which is different from the first to third embodiments. The magnetic recording medium 500 is formed by sequentially laminating a recording holding layer 3, a recording control layer 4, a recording layer 5, a mask layer 52, a magnetic transfer layer 54, a protective layer 6 and a lubricating layer 7 on a substrate 1.

  The recording holding layer 3 is composed of an antiferromagnetic film NiO exhibiting perpendicular magnetic anisotropy, and its composition is adjusted so that the Curie temperature Tc3 is 450 ° C. The recording control layer 4 was formed using a magnetic film DyFeCo exhibiting perpendicular magnetic anisotropy, and its composition was adjusted so that the Curie temperature Tc2 was 200 ° C. DyFeCo whose composition has been adjusted exhibits a rare earth dominant (RE-rich) polarity from room temperature to Curie temperature.

  The mask layer 52 is formed using an amorphous ferrimagnetic film GdFeCo, and its Curie temperature Tc4 is 300 ° C., shows in-plane magnetization from room temperature to 150 ° C., and shows perpendicular magnetization at 150 ° C. or more. The composition was adjusted. The critical temperature at which the stable magnetization direction changes from in-plane to perpendicular is called the perpendicularization temperature and is represented by Tcr4. The magnetic transfer layer 54 is composed of an amorphous ferrimagnetic film GdFeCo, and has a Curie temperature Tc5 of 300 ° C., showing perpendicular magnetization from room temperature to 110 ° C., and in-plane magnetization from 110 ° C. to 150 ° C. The composition was adjusted to show perpendicular magnetization from 150 ° C. to 300 ° C. Here, the critical temperature (110 ° C.) at which the stable magnetization direction changes from perpendicular to in-plane is called the in-plane temperature and is represented by Tcr′5. Further, the magnetic material of the magnetic transfer layer 54 has a property that the exchange coupling force in the in-plane direction becomes stronger at a high temperature.

  As the materials constituting the recording layer 5, the protective layer 6, and the lubricating layer 7, the same materials as those of the magnetic recording medium manufactured in Example 1 were used. The recording holding layer 3, the recording control layer 4, the recording layer 5, the mask layer 52, the magnetic transfer layer 54, and the protective layer 6 are sequentially formed by sputtering, and the thickness of each layer is 50 nm, 10 nm, 100 nm, They were 5 nm, 15 nm, and 10 nm. Next, the lubricating layer 7 was formed on the protective layer 6 with a film thickness of 2 nm by spin coating. Thus, the magnetic recording medium 500 having the structure shown in FIG. 16 was manufactured.

Recording and Reproduction of Information The above magnetic recording medium 500 is the same recording as that of Example 3 except that a reproducing MR head 123 ′ that detects in-plane magnetization is used instead of the reproducing MR head 123 that detects perpendicular magnetization. Recording and reproduction can be performed using a reproduction head. Recording and reproduction are performed by loading the magnetic recording medium 500 in an evaluation device (drive) and disposing the recording / reproducing head 210 on the lubricant layer side (opposite side of the substrate) of the magnetic recording medium 500.

  Here, the recording and reproducing principles of the magnetic recording medium 500 will be described with reference to FIGS. FIG. 17A shows a state in which a predetermined region of the magnetic recording medium 500 is irradiated with a laser beam condensed from the side opposite to the substrate 1 (upper side in the drawing). The magnetic recording medium 500 rotates at a predetermined linear velocity, and the magnetic recording medium is moved in the left direction in FIG. As shown in the temperature distribution graph of FIG. 17A, the laser beam power is such that the maximum temperature Tmax (maximum value indicating the Gaussian distribution) of the region irradiated with the light spot 41 is the recording holding layer 3. The Curie temperature Tc3 (450 ° C.) of the recording layer 5 is adjusted to be equal to or lower than the Curie temperature Tc (300 ° C.) of the recording layer 5. At the same time as irradiating the magnetic recording medium 500 with laser light, an external magnetic field Hex is applied vertically upward to the surface of the magnetic recording medium 500 using the recording magnetic head 122 (single pole head).

  In FIG. 17A, when the magnetic recording medium 500 moves to the left with respect to the light spot 41, the region 45 (high temperature region) heated by the irradiation of the light spot 41 is separated from the light spot 41 and cooled. FIG. 17B shows how the magnetization of each magnetic layer changes during the cooling process of the high temperature region 45. In FIG. 17B, when the temperature of the high temperature region 45 is represented by T, (1) When Tc4 <T <Tc, the magnetization of the recording layer is TM-rich in the direction of the external magnetic field Hex (upward in the figure). Appear. (2) When Tc2 <T <Tc4, the magnetization of the mask layer and the magnetic transfer layer faces downward in the figure by RE-rich due to exchange coupling with the magnetization of the recording layer (however, in FIG. Appears as lattice magnetization (upward). (3) When Tcr4 <T <Tc2, the magnetization of the recording control layer appears in the same direction as the magnetization of the recording layer due to exchange coupling, and at the same time, the magnetization state of the recording layer is firmly fixed by exchange coupling with the magnetization of the recording holding layer. Is done. (4) When Tcr′5 <T <Tcr4, the magnetization of the mask layer 24a is directed from the vertical direction to the in-plane direction. (5) At room temperature <T <Tcr′5, the magnetization of the magnetic transfer layer 24b is directed from the in-plane direction to the vertical direction. Information is thus recorded on the recording layer. The above is the principle of recording on the magnetic recording medium 500.

  Next, the principle of reproducing information recorded by the above-described recording principle will be described. First, as shown in FIG. 18, a case where the recording magnetic domain of the recording layer to be reproduced is formed downward will be described. While the magnetic recording medium 500 is rotated at a predetermined linear velocity, the magnetic recording medium 500 is heated by irradiating a reproducing laser beam having a low laser power. By irradiating the magnetic recording medium 500 with the reproducing laser beam, the surface of the magnetic recording medium is heated with a temperature distribution as shown in the lower part of FIG. At this time, only the magnetization 180 in the temperature region of the mask layer 52 not lower than the verticalizing temperature Tcr4 (150 ° C.) changes from the in-plane direction to the vertical direction. When the downward magnetization 181 is formed in the recording layer, the magnetization 180 of the mask layer 52 exchange-couples with the downward magnetization 181 of the recording layer located immediately below the mask layer 52 to reflect the magnetization state of the recording layer. The direction, that is, the downward direction in FIG.

  The magnetization 182 in the temperature region of 150 ° C. or more of the magnetic transfer layer 54 changes from the in-plane direction to the perpendicular direction, and is exchange-coupled with the magnetization 180 of the mask layer 52 to reflect the magnetization state of the recording layer 5, that is, 18 downwards. The magnetization 183 in the temperature region of the in-plane temperature Tcr′5 (110 ° C.) or higher and lower than 150 ° C. of the magnetic transfer layer 54 changes from the vertical direction to the in-plane direction. At this time, the magnetization 183 of the magnetic transfer layer 54 becomes a magnetization directed diagonally downward to the right as shown in FIG. 18 due to the magnetic field from the magnetization 181 of the recording layer 5 and the magnetization 184 of the recording control layer. The in-plane component of the rightward downward magnetization of the magnetic transfer layer 54 is detected by the MR head 123 'for detecting in-plane magnetization. In this way, the downward magnetization of the recording layer is transferred to the magnetic transfer layer, and the information is reproduced by expanding it to a temperature region of the in-plane temperature Tcr′5 (110 ° C.) or higher of the magnetic transfer layer.

  The above is the reproduction principle when the recording magnetic domain to be reproduced is downward. Next, the case where the recording magnetic domain faces upward will be described with reference to FIG. Similarly to the above, when the reproducing laser beam is irradiated onto the magnetic recording medium 500, the surface of the magnetic recording medium is heated with a temperature distribution as shown in the lower part of FIG. At this time, only the magnetization 190 in the temperature region equal to or higher than the perpendicularization temperature Tcr4 (150 ° C.) of the mask layer 52 changes from the in-plane direction to the vertical direction, and the upward magnetization 191 of the recording layer located immediately below the mask layer 52 The direction is exchange-coupled to reflect the magnetization state of the recording layer, that is, upward in FIG.

  Then, the magnetization 192 in the temperature region of 150 ° C. or more of the magnetic transfer layer 54 changes from the in-plane direction to the perpendicular direction, exchange-coupled with the magnetization 190 of the mask layer 52, and reflects the magnetization state of the recording layer 5. That is, it faces upward in FIG. The magnetization 193 in the temperature region of the magnetic transfer layer 54 in the in-plane temperature Tcr′5 (110 ° C.) or more and less than 150 ° C. changes from the vertical direction to the in-plane direction, and the magnetization 191 of the recording layer 5 and the magnetization of the recording control layer. Due to the magnetic field from 194, the magnetization becomes diagonally upward to the left as shown in FIG. The in-plane component of the leftward upward magnetization of the magnetic transfer layer 54 is detected by the MR head 123 'for detecting in-plane magnetization. Thus, the upward and downward magnetizations formed in the recording layer are distinguished and reproduced. The above is the principle of reproduction of the magnetic recording medium 500.

  As described above, in this embodiment, the recording magnetic domains of the recording layer 5 are independently transferred to the magnetic transfer layer 54 via the mask layer 52 and transferred from the enlarged magnetic transfer layer 54. Therefore, a reproduction signal having a larger amplitude than the reproduction signal detected from the recording layer 5 can be obtained. Furthermore, since information can be reproduced using an inexpensive MR head for detecting in-plane magnetization, the cost for manufacturing the drive can be reduced.

Example 5
Next, an embodiment in which information is reproduced using an inductive magnetic head instead of the magnetoresistive element will be described.

  In the present embodiment, a magneto-optical recording medium (hereinafter referred to as a DWDD medium) according to DWDD (Domain Wall Displacement Detection) is used as the magneto-optical recording medium. FIG. 21 shows a cross-sectional structure of a magneto-optical recording medium 230 according to DWDD. As shown in FIG. 21, the DWDD medium 230 includes a protective layer 232, a memory layer (recording layer) 233, a switching layer 234, a moving layer (reproducing layer) 235, a protective layer 236, and a lubricant layer 237 on a substrate 231. Are sequentially stacked.

  The substrate 231 is a polycarbonate substrate manufactured by an injection molding method, and is a land / groove type substrate having lands and grooves having a width of 0.6 μm. The protective layer 232 provided on the substrate 231 is made of SiN and has a thickness of 60 nm. The memory layer 233 is a layer on which information is recorded, is made of TbFeCoCr, and has a thickness of 80 nm. In the memory layer 233, the composition of TbFeCoCr was adjusted so that the compensation temperature was about 80 ° C. and the Curie temperature was about 230 ° C.

  The switching layer 234 is made of TbFeCr, and its composition is adjusted so that the compensation temperature is about 50 ° C. and the Curie temperature is about 110 ° C. The film thickness of the switching layer 234 is 10 nm. The moving layer 235 is made of GdFeCr, and its composition is adjusted so that the compensation temperature is not more than room temperature and the Curie temperature is about 240 ° C. The thickness of the moving layer 235 is 30 nm. The protective layer 236 is made of SiN and has a thickness of 50 nm. These layers 232 to 236 are sequentially formed using a sputtering apparatus. The lubricant layer 237 formed on the protective layer 236 is a homblin lubricant and is applied by spin coating with a film thickness of 2 nm.

  Here, the principle in the conventional reproducing method of the DWDD medium will be briefly described. Details of the playback principle are described in, for example, “Proceedings of Magneto-Optical Recording International Symposium '97, J.Magn.Soc.Jpn., Vol.22 Supplement No.S2 (1998), PP.47-50”. So you can refer to this.

  As shown in FIG. 22, when the DWDD medium is irradiated with the laser light 241, the DWDD medium is heated according to the temperature distribution of the laser light 241. In the region 242 heated to the Curie temperature Ts or higher of the switching layer 234, the magnetization disappears, and the exchange coupling between the moving layer 235 and the memory layer 233 located above and below the region 242 is released. The region 242 in which the magnetization of the switching layer 234 has disappeared will be referred to as a bond cut region in the following description. When the DWDD medium is scanned with the light spot, the domain wall 243 (the boundary portion between the upward magnetic domain and the downward magnetic domain) enters the front boundary 245 of the coupling cut region 242. In general, since the force applied to the domain wall depends on the domain wall energy density, and the domain wall energy density is a function of temperature, the force applied to the domain wall is generated by a temperature gradient around the domain wall. Therefore, as shown in the lower graph of FIG. 22, a force F (x) is generated on the domain wall 243 from the low temperature side to the high temperature side in the track direction, with the right direction being the positive direction. Therefore, the domain wall 243 of the moving layer 235 that has lost the constraint in the track direction due to the exchange coupling force moves to the peak temperature position 246 of the temperature distribution in the light spot by the force F (x). Since the moving speed of the domain wall 243 is faster than the moving speed of the medium, the magnetic domain of the moving layer 235 on the upper layer of the coupling cut region 242 expands in the track direction. Thereby, the reproduction signal amplitude read from the moving layer 235 by the magneto-optic effect (Kerr effect) becomes larger than the reproduction signal amplitude when the magnetic domain recorded in the memory layer 233 is directly read. In other words, even if the magnetic domain recorded in the memory layer 233 is very small, it can be reproduced with an amplified reproduction signal.

  When the isolated magnetic domain recorded on the DWDD medium is subjected to conventional magneto-optical reproduction, two reproduced waveforms are observed as shown in FIG. The mechanism will be described with reference to FIGS. The numbers (1) to (4) shown in FIG. 23 correspond to (1) to (4) in FIG. Hereinafter, the states (1) to (4) will be briefly described. (1) When the domain wall 252 on the left side of the isolated magnetic domain 251 (moving upward domain) of the moving layer 235 enters the position of the front boundary 245 of the coupling cut region 242, the domain wall 252 is formed in the moving layer 235 in accordance with the principle described above. Moves leftward in the figure toward the peak temperature position. (2) When the DWDD medium moves with respect to the light spot and the domain wall 253a on the right side of the isolated magnetic domain 253 of the memory layer 233 enters the position of the front boundary portion 245 of the coupling cut region, the domain wall 252 is formed in the moving layer 235. Moves to the position of the peak temperature of the temperature distribution in the left direction in the figure. (3) When the DWDD medium further moves with respect to the light spot, the domain wall 253b on the left side of the isolated magnetic domain 253 of the memory layer 233 passes through the rear boundary portion 247 of the coupled cutting region. The isolated magnetic domain 253 of the portion of the memory layer 233 that has passed through is transferred to the moving layer 235 by exchange coupling in the region on the left side of the coupling cut region. The domain wall 254 located on the right side of the rear boundary 247 of the moving layer 235 moves to the right toward the peak temperature position. (4) Further, when the DWDD medium moves with respect to the light spot, the domain wall 253a on the right side of the isolated magnetic domain 253 of the memory layer 233 passes through the rear boundary portion 247 of the coupling cut region, and the downward portion of the memory layer 233 passes through the portion. The magnetic domain (space) 255 is transferred to the moving layer 235 by exchange coupling on the left side of the bond cutting region. Then, the domain wall 256 in the moving layer 235 at the rear boundary 247 moves rightward toward the peak temperature. This indicates that two reproduced signals are observed for one isolated magnetic domain to be read. In FIG. 23, the reproduction signals (1) and (2) are reproduction signals to be read, and the reproduction signals (3) and (4) are unintended reproduction signals. The reproduction signals (3) and (4) are called ghost signals. Thus, it is not preferable that two reproduced signals are observed from one isolated magnetic domain. This is because if the magnetic domain interval is narrowed for further higher density, it becomes difficult to individually distinguish these reproduced signals. In this embodiment, such a problem can be effectively prevented by reproducing using an induction type magnetic head as will be described later. Hereinafter, an example in which information recorded on a DWDD medium is reproduced using an induction type magnetic head will be described.

  FIG. 25 is a conceptual diagram showing how a DWDD medium is reproduced using an induction type magnetic head. As shown in the figure, the optical system is arranged so that laser light is incident on the substrate 231 side of the DWDD medium 230, and the induction type magnetic head 260 is arranged at a position facing the optical system via the medium 230. The The optical system includes a laser light source (not shown) that emits laser light having a wavelength λ = 680 nm, and an objective lens having a numerical aperture NA = 0.55. Focusing and tracking servo can be performed by irradiating the medium with such laser light and detecting light reflected from the medium.

  The induction type magnetic head 260 is a single-pole contact type magnetic head including a core 261 (magnetic core) and a coil 262. The core 261 can be configured using, for example, permalloy. The portion of the core 261 that is in contact with the medium is processed so that the dimension in the track width direction is about 1.0 μm and the length in the track direction (hereinafter referred to as the head length) is about 0.5 μm. The number of turns of the coil 262 is 100. The inductive magnetic head 260 can record a recording magnetic domain in the memory layer by generating a recording magnetic field during information recording. Further, at the time of information reproduction, information can be reproduced by changing the leakage magnetic field from the recording magnetic domain into an electric signal using an electromotive force due to electromagnetic induction.

The reproduction output e of the induction type magnetic head 260 is expressed as follows, where N is the number of coil turns, Φ is magnetic flux, and t is time.
e = -N (dΦ / dt)
It is represented by If we change this formula further,
e = −N (dΦ (x) / dx) (dx / dt) = N (dΦ / dx) v (1)
It becomes. v is a relative moving speed (linear velocity) of the medium with respect to the induction type magnetic head.

  In this embodiment, information is recorded on the land of the DWDD medium 230. When recording information, the memory of the groove is formed in order to form a recording magnetic domain in the memory layer that is not closed. The magnetism of the groove memory layer was degraded by annealing the layer. The annealing conditions were linear velocity v = 1.5 m / s and annealing laser power Pa = 10.0 mW. The middle part of FIG. 26 shows the distribution in the track direction of the magnetic flux Φ interlinking with the coil of the induction type magnetic head when continuous magnetic domains are formed on the DWDD medium. The reproduction signal output when reproducing such a continuous magnetic domain has a waveform similar to the waveform shown in the lower part of the figure according to the above equation (1).

  Next, a continuous magnetic domain of 0.8 μm was recorded on the DWDD medium 230 by a magnetic field modulation method. The recording conditions were linear velocity v = 1.5 m / s, recording power Pw = 3.0 mW, and recording magnetic field Hw = ± 400 Oe. The recorded magnetic domain was reproduced using an induction type magnetic head while irradiating a laser beam. FIG. 27 shows the reproduction output (Δx = 0.2 μm). In FIG. 27, the solid line indicates the reproduction output when normal reproduction is performed with the reproduction laser power Pr = 1.0 mW, and the dotted line is the reproduction output when DWDD reproduction is performed with the reproduction laser power Pr = 1.7 mW. Here, normal reproduction means that since the switching layer temperature is equal to or lower than its Curie temperature, the magnetic domain of the memory layer is transferred to the moving layer through the switching layer by exchange coupling without moving, and the moving layer moves. In this layer, information is reproduced without domain wall movement. DWDD reproduction is a method in which a coupling disconnection region is formed in the switching layer, and information is reproduced by generating magnetic movement in the moving layer as described above. Is a playback method.

  In normal reproduction, “v” in the above equation (1) corresponds to a linear velocity of 1.5 m / s. On the other hand, in DWDD reproduction, “v”, that is, the domain wall motion speed becomes several tens of times or more. Therefore, as shown in FIG. 27, in the DWDD reproduction, the reproduction output is larger than that in the normal reproduction, and the half width of the reproduction signal waveform is small. From the viewpoint of resolution in the track direction, this indicates that DWDD reproduction by an induction type magnetic head is extremely effective as a method for reproducing information recorded at high density.

  Next, it was examined how the reproduction signal changes by changing the relative position (Δx) of the core center of the induction type magnetic head with respect to the center of the light spot. FIG. 28 shows the Δx dependency of the reproduction output when the isolated magnetic domain of 0.8 μm is reproduced by DWDD. As shown in the figure, the reproduction signal was observed by placing the core of the inductive magnetic head at a position shifted by Δx from the center of the light spot. Here, the right side in the figure is positive and the left side is negative. A ghost signal was observed when Δx = −0.2 μm, that is, when the core center was on the left side (the rear side in the medium movement direction) of the center of the light spot. On the other hand, when Δx is large, that is, when the core center is on the right side (front side in the medium movement direction) with respect to the light spot center, the amplitude of the ghost signal becomes small, and it can be seen that it disappears. This means that the ghost signal can be suppressed if the core center of the magnetic head is between the front boundary portion of the coupling cut region and the peak temperature position in FIG.

  In the DWDD reproduction, in the temperature distribution generated by irradiating laser light, the domain wall moves in the moving layer toward the position where the peak temperature is reached. When Δx = −0.2 μm to 0.1 μm, it is considered that a ghost signal was observed because the peak temperature is located directly under the core of the induction type magnetic head. On the other hand, when Δx ≧ 0.2 μm, the peak temperature position deviates outside the core, so that it can be considered that no ghost signal is observed.

  As described above, by reproducing the DWDD medium using the induction type magnetic head (DWDD reproduction), it is possible to obtain a reproduction output larger than that of the normal reproduction, and further, it is possible to suppress a decrease in resolution due to high-density recording. did it. Further, the ghost signal is obtained by setting the core length of the core of the induction type magnetic head to about half of the diameter of the light spot and disposing the core at the front side (right side in FIG. 28) in the medium traveling direction from the center of the light spot. Could be suppressed.

  As mentioned above, although this invention was concretely demonstrated using drawing, this invention is not limited to the said Examples 1-5, It cannot be overemphasized that the change and improvement which those skilled in the art can think are included. For example, an underlayer for controlling the magnetic anisotropy is provided between the substrate 1 and the recording auxiliary layer 2 in the first and second embodiments and between the substrate 1 and the recording holding layer 3 in the third and fourth embodiments. It may be provided.

  In the magnetic recording medium of the present invention, a recording layer is formed using a ferrimagnetic material having perpendicular magnetization, and information is recorded at an extremely high density by applying a recording magnetic field while applying heat to a predetermined area of the medium. can do. Further, since the recording layer has a large coercive force of 5 kOe or more at room temperature, even if a minute recording mark is formed on the recording layer, the disappearance of the recording mark due to the thermomagnetic relaxation phenomenon is prevented or suppressed.

  According to the recording method of the magnetic recording medium of the present invention, the magnetic head having a magnetic pole width of 1 μm or less in the direction perpendicular to the recording direction while applying heat to the magnetic recording medium having the recording layer having perpendicular magnetization. Can be recorded at a high density, so that it is extremely suitable as a recording method for the magnetic recording medium of the present invention.

  In addition, according to the method for reproducing a magnetic recording medium of the present invention, information recorded perpendicularly on the magnetic recording medium while applying heat to the magnetic recording medium is converted into a magnetic element having a magnetoresistive element or a spin valve film, an induction type Since it can be reproduced using a magnetic element, it is suitable as a method for reproducing the magnetic recording medium of the present invention.

  The recording / reproducing head of the present invention includes a heat source for heating the magnetic recording medium, a magnetic field generation source and a magnetic element mounted on the air slider, and uses the heat source to heat the magnetic recording medium. Information can be recorded with high density by using a magnetic field generation source mounted on an air slider. As the magnetic element, for example, a magnetoresistive element, a magnetic element including a spin valve film, or an inductive magnetic element can be used. Also, since information recorded at high density can be reproduced using these magnetic elements, it is suitable as a recording / reproducing head of the magnetic recording medium of the present invention.

  Further, according to the recording method of the information recording medium of the present invention, a recording mark smaller than the light spot is formed in the area inside the light spot while projecting the light spot on the information recording medium having the recording layer having perpendicular magnetization. Since it can be formed, it is extremely suitable as a recording method for an ultra-high-density information recording medium.

It is a schematic sectional drawing of one specific example of the magnetic recording medium according to this invention. It is a schematic sectional drawing of one specific example of the recording / reproducing head according to this invention. It is a figure which shows the temperature characteristic of the coercive force of the recording layer of the magnetic recording medium according to this invention. FIG. 4A is a diagram showing an outline of a recording / reproducing experiment of the magnetic recording medium, and FIG. 4B is a sectional view of the arrangement of the magnetic recording medium and the recording / reproducing head. It is a figure explaining the recording principle of the magnetic recording medium shown in FIG. It is the graph shown about the environmental durability of the S / N ratio of the magnetic recording medium according to this invention. It is the graph which compared the environmental durability of the S / N ratio of the magnetic recording medium according to this invention, and the conventional magnetic recording medium. It is a graph which shows the mode of the change of the reproduction output with respect to the recording mark length of a magnetic recording medium. 6 is a schematic cross-sectional view of a magnetic recording medium according to the present invention manufactured in Example 2. FIG. 10 is a graph showing temperature characteristics of saturation magnetization of the reproducing layer and the recording layer of the magnetic recording medium shown in FIG. 9. It is a figure explaining the recording principle of the magnetic recording medium shown in FIG. 6 is a schematic sectional view of a magnetic recording medium according to the present invention manufactured in Example 3. FIG. 6 is a schematic cross-sectional view of a recording / reproducing head according to the present invention used in Example 3. FIG. It is a figure explaining the recording principle of the magnetic recording medium shown in FIG. It is a figure explaining the reproduction | regeneration principle of the magnetic recording medium shown in FIG. 6 is a schematic sectional view of a magnetic recording medium according to the present invention manufactured in Example 4. FIG. It is a figure explaining the recording principle of the magnetic recording medium shown in FIG. FIG. 17 is a diagram for explaining the reproduction principle when a downward recording magnetic domain is formed in the recording layer of the magnetic recording medium shown in FIG. 16. FIG. 17 is a diagram for explaining the reproduction principle when an upward recording magnetic domain is formed in the recording layer of the magnetic recording medium shown in FIG. 16. It is a figure which shows typically the cross-sectional structure of a single pole head. 6 is a schematic cross-sectional view of a magneto-optical recording medium according to DWDD manufactured in Example 5. FIG. It is a figure for demonstrating the basic principle in the conventional reproduction | regeneration method of a DWDD medium. This is a reproduction waveform when an isolated magnetic domain is subjected to conventional magneto-optical reproduction, and shows a state in which two reproduction waveforms are observed. It is a figure for demonstrating the mode of (1)-(4) of the reproduction | regeneration waveform shown in FIG. It is a conceptual diagram of a mode that a DWDD medium is reproduced using an induction type magnetic head. FIG. 6 is a diagram showing a track direction distribution of a magnetic flux Φ interlinked with a coil of an induction type magnetic head and a reproduction signal output when continuous magnetic domains are formed on a DWDD medium. It is a figure which shows the reproduction output at the time of carrying out normal reproduction | regeneration of a continuous magnetic domain, and the reproduction output at the time of DWDD reproduction. It is a figure which shows a mode that a reproduction signal changes by changing the relative position ((DELTA) x) of the core center of the induction | guidance | derivation type magnetic head with respect to a light spot center.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording auxiliary layer 3 Recording holding layer 4 Recording control layer 5 Recording layer 50 Reproducing layer 52 Mask layer 54 Magnetic transfer layer 20, 120 Head main body 22, 122 Recording magnetic head 23, 123 Reproducing MR head 27, 127 Laser light source 31 Heat source 100, 300, 400, 500 Magnetic recording medium 200, 210 Recording / reproducing head

Claims (17)

In a recording and / or reproducing head for a magnetic recording medium,
A magnetic field source for applying a recording magnetic field to the magnetic recording medium;
A magnetic element for reading magnetization information of a magnetic recording medium, and a kind of magnetic element selected from the group consisting of a magnetoresistive element, a magnetic element having a spin valve film, and an inductive magnetic element;
A recording and / or reproducing head comprising: an air slider on which the magnetic field generation source and the magnetic element are mounted. The recording and / or reproducing head according to claim 1, further comprising a heat source for heating the magnetic recording medium. The recording and / or reproducing head according to claim 2, wherein the heat source is a laser light source, and the magnetic recording medium is heated by laser light emitted from the laser light source. The recording and / or reproducing head according to claim 1, wherein the air slider is made of a plurality of materials having different thermal conductivities. 5. The recording and / or reproducing device according to claim 4, wherein the magnetic field generation source and the magnetic element are made of a material having a low thermal conductivity among the plurality of materials having different thermal conductivities. head. 5. The recording and / or recording according to claim 4, wherein a material having a high thermal conductivity among the plurality of materials having different thermal conductivity is configured between the magnetic field generation source and the magnetic element. Reproduction head. The recording and / or reproducing head according to claim 2, wherein the magnetic field generation source, the magnetic element, and the heat source are all disposed on one surface side of the magnetic recording medium. . 7. The recording and / or reproducing device according to claim 2, wherein the magnetic field generation source, the magnetic element, and the heat source are disposed to face each other with a magnetic recording medium interposed therebetween. head. When recording or reproduction is performed while moving the magnetic recording medium relative to the head, a heat source is disposed in the head in the moving direction of the magnetic recording medium, and a magnetic element is disposed in the head in the rear. The recording and / or reproducing head according to any one of claims 2 to 8. The magnetic element is an inductive magnetic element, and when performing recording or reproduction while moving the magnetic recording medium relative to the head, the magnetic element is on the front side in the moving direction of the magnetic recording medium, and the heat source is on the rear side. The recording and / or reproducing head according to claim 2, wherein the recording and / or reproducing head is disposed within the recording head. The magnetic recording medium is a recording medium comprising at least a magnetic layer having a magnetic property in which a domain wall of a magnetic domain moves in a film in-plane direction according to a heat distribution formed by heat from a heat source. Recording and / or reproducing head. The recording and / or reproducing head according to claim 1, wherein the magnetic field generation source is constituted by a single magnetic pole head. The recording and / or reproducing head according to claim 12, wherein at least a part of the single magnetic pole head is made of a material having a saturation magnetic flux density of 2.0 T or more. 14. The recording and / or reproducing head according to claim 13, wherein the magnetic field generating portion of the single pole head is made of a material having a saturation magnetic flux density of 2.0 T or more. 15. The recording and / or reproducing head according to claim 13, wherein the material having a saturation magnetic flux density of 2.0 T or more is CoNiFe or an alloy containing the same. The magnetic recording medium has a plurality of tracks;
The recording and / or recording according to any one of claims 12 to 15, wherein the single magnetic pole head is configured by winding a coil around a core, and the width of the tip of the core in the track width direction is 1 µm or less. Or playback head. The information recording medium has a recording layer on a substrate,
The recording layer is made of a ferrimagnetic material having perpendicular magnetization, and by applying a recording magnetic field while heating a predetermined area of the magnetic recording medium, the recording magnetic domain of the recording layer is reversed and information is recorded. 2. The recording and / or reproducing head according to claim 1, wherein the recording and reproducing head is a magnetic recording medium on which information is reproduced by detecting a magnetic field from a recording magnetic domain of the layer.

Images