JP2009223940A - Magnetic recording medium and magnetic recording and playback device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a perpendicular recording magnetic recording medium which easily reduces coercive force of a heated part of a recording layer so as to be magnetized or magnetically reversed, and to provide a magnetic recording and playback device equipped with the magnetic recording medium. <P>SOLUTION: The magnetic recording medium 16 includes a substrate 24, a soft magnetic layer 26, a heat insulation layer 28, an alignment layer 30 and a recording layer 12. The layers are formed on the substrate 24 in this order. Thermal conductivity of the heat insulation layer 28 is lower than that of the alignment layer 30 and lower than that of the soft magnetic layer 26. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium on which magnetic data is recorded by applying and heating a magnetic field and magnetic data is magnetically reproduced, and a magnetic recording / reproducing apparatus including the same.

  Conventionally, magnetic recording / reproducing apparatuses such as hard disks have significantly increased surface recording density by improving the processing head, the processing of the reproducing head, the refinement of magnetic particles constituting the recording layer of the magnetic recording medium, and the change of materials. Is planned. On the other hand, there is a problem that thermal fluctuation is likely to occur with the miniaturization of magnetic particles constituting the recording layer.

  On the other hand, in recent years, a substrate, a soft magnetic layer, an orientation layer for enhancing the orientation of the recording layer, and a recording layer oriented so that the recording layer is magnetized in a direction perpendicular to the surface of the magnetic recording medium, A perpendicular recording type comprising a magnetic recording medium in which these layers are formed on a substrate in this order, and the recording layer is magnetized in a direction perpendicular to the surface of the magnetic recording medium Magnetic recording / reproducing apparatuses are becoming popular.

  Furthermore, a magnetic recording medium having a recording layer made of a material having a larger magnetic anisotropy energy and a larger coercive force than before, a heating head, and a recording head are provided, and the heating head is irradiated with a light beam or the like. A heat-assisted magnetic recording / reproducing apparatus configured to temporarily reduce the coercive force by partially heating the recording layer and recording the magnetic data by applying a recording magnetic field to the heated portion. Has been proposed.

  By adopting a perpendicular recording magnetic recording medium in a heat-assisted magnetic recording / reproducing apparatus, a synergistic improvement in surface recording density is expected (see, for example, Patent Document 1).

JP 2008-34004 A

  However, even when the heating head heats the recording layer by irradiation with a light beam, the coercive force of the heated portion of the recording layer may not be sufficiently reduced to a level at which magnetization or magnetization reversal can be achieved with the recording magnetic field generated by the recording head. . In particular, when a perpendicular recording type magnetic recording medium is employed, it has been found that it is difficult to sufficiently reduce the coercivity of the heated portion of the recording layer to a level at which magnetization or magnetization reversal is possible.

  The present invention has been made in view of the above problems, and a perpendicular recording type magnetic recording medium capable of easily reducing the coercivity of the heated portion of the recording layer to a level at which magnetization or magnetization reversal can be achieved, and such a recording medium. An object of the present invention is to provide a magnetic recording / reproducing apparatus including a magnetic recording medium.

  The present invention provides the above-mentioned target by forming a heat insulating layer between the soft magnetic layer and the orientation layer having a thermal conductivity lower than that of the orientation layer and lower than that of the soft magnetic layer. Is achieved.

  When the inventors adopt a perpendicular recording type magnetic recording medium as described above in the process of conceiving the present invention, the coercive force of the heated portion of the recording layer is sufficiently reduced to a level at which magnetization or magnetization reversal is possible. I noticed that it was difficult, and investigated the cause. As a result, the perpendicular recording type magnetic recording medium has a soft magnetic layer below the recording layer, and the soft magnetic layer is made of a material whose main component is a metal, so that the thermal conductivity is high. Is significantly thicker than the recording layer, and the heat applied to the heated part of the recording layer is easily absorbed by the soft magnetic layer, so the temperature of the heated part of the recording layer does not rise sufficiently and the coercive force is sufficiently reduced I guessed not.

  On the other hand, by forming a heat insulating layer having a thermal conductivity lower than that of the orientation layer and lower than that of the soft magnetic layer between the soft magnetic layer and the orientation layer, the recording layer Heat conduction from the heated portion to the soft magnetic layer can be suppressed, and the temperature of the heated portion of the recording layer can be sufficiently increased.

  That is, the following problems can be solved by the present invention as follows.

(1) including a substrate, a soft magnetic layer, a heat insulating layer, an orientation layer, and a recording layer, and these layers are formed on the substrate in this order, and the heat conductivity of the heat insulating layer is A magnetic recording medium characterized by being lower than the thermal conductivity of the alignment layer and lower than the thermal conductivity of the soft magnetic layer.

(2) The magnetic recording medium according to (1), wherein the alignment layer is made of a material whose main component is a metal.

(3) The magnetic recording medium according to (1) or (2), wherein the recording layer is formed with a concavo-convex pattern and a recording element for recording magnetic data is formed with a convex portion of the concavo-convex pattern. .

(4) The magnetic recording medium according to any one of (1) to (3), a heating head for heating the recording layer, a recording head for applying a recording magnetic field to the recording layer, and the recording And a reproducing head for detecting a reproducing magnetic field of the layer.

  In the present application, “a magnetic recording medium in which a recording layer is formed with a concavo-convex pattern and a recording element for recording magnetic data is formed with a convex portion of the concavo-convex pattern” refers to a large number of recording elements with a predetermined pattern. In addition to a magnetic recording medium having a divided recording layer, a magnetic recording medium having a recording layer in which a concave portion is formed in the middle of the thickness direction and the surface on the substrate side is continuous, and is formed following the surface of a substrate with a concave-convex pattern or a lower layer A magnetic recording medium having a continuous recording layer formed thereon, a substrate having a concavo-convex pattern, a portion formed on a top surface of a convex portion and a portion formed on the top surface of the convex portion and divided into a bottom surface of a concave portion, forming a recording element It is used in the meaning including a magnetic recording medium having a layer.

  Further, in the present application, the term “magnetic recording medium” is used in the meaning including other magnetic recording media such as a floppy (registered trademark) disk in addition to a hard disk.

  According to the present invention, it is possible to realize a perpendicular recording type magnetic recording medium that can easily reduce the coercivity of the heated portion of the recording layer to a level at which magnetization or magnetization can be reversed, and a magnetic recording / reproducing apparatus including such a magnetic recording medium. .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIGS. 1 to 4, in the magnetic recording / reproducing apparatus 10 according to the first embodiment of the present invention, the recording layer 12 is formed in a concavo-convex pattern and the recording element 12A for recording magnetic data has a concavo-convex pattern. A perpendicular recording type magnetic recording medium 16 formed of convex portions, a heating head 18 for heating the recording element 12A to reduce the coercive force of the recording element 12A, and a recording magnetic field for applying a recording magnetic field to the recording element 12A A recording head 20 and a reproducing head 22 for detecting the reproducing magnetic field of the recording element 12A are provided.

The magnetic recording medium 16 is a patterned medium of the substantially disc-shaped member, and rotates in the arrow direction in the circumferential direction D _C shown is driven by a motor (not shown) in FIG. 1 and the like.

  The magnetic recording medium 16 has a substrate 24, a soft magnetic layer 26, a heat insulating layer 28, an orientation layer 30, and a recording layer 12, and these layers are formed on the substrate 24 in this order. The thermal conductivity of the heat insulating layer 28 is lower than the thermal conductivity of the orientation layer 30 and lower than the thermal conductivity of the soft magnetic layer 26. Further, the heat conductivity of the heat insulating layer 28 is lower than the heat conductivity of the recording layer 12. Further, the recesses between the recording elements 12 </ b> A are filled with a filler 32 having a lower thermal conductivity than the recording layer 12. On the recording element 12A and the filler 32, a protective layer 34 and a lubricating layer 36 are formed in this order.

The recording layer 12 has a thickness of 5 to 30 nm. As the material of the recording layer 12, for example, a material having a perpendicular magnetic anisotropy energy of 1 × 10 ⁶ erg / cc or more can be used. Specific examples of the recording layer 12 include a CoCr alloy such as a CoCrPt alloy, a CoPt alloy, an FePt alloy, a laminate thereof, a Co / Pd multilayer film, and a Co / Pt multilayer film. The thermal conductivity of the recording layer 12 is, for example, 10 to 120 W / m · K.

Recording element 12A is a convex portion of the recording layer 12 is formed in a shape divided at minute intervals track 14 in the circumferential direction D _C in the data area. That is, the recording element 12A has a plurality of juxtaposed in the circumferential direction D _C in each track 14, FIGS. 1 and 4 illustrates this. Each recording element 12A corresponds to one recording bit (one recording bit is recorded in one recording element 12A). Incidentally, as shown in FIG. 2, the recording element 12A is divided at minute intervals in the track width direction D _TW in the data area. In addition, the recording layer 12 is formed with a concavo-convex pattern (not shown) corresponding to a pattern such as predetermined servo information in the servo area.

The substrate 24 has a substantially disk shape having a center hole. As a material of the substrate 24, glass, Al, Al ₂ O ₃ or the like can be used.

  The soft magnetic layer 26 has a thickness of 20 to 300 nm. As a material of the soft magnetic layer 26, an Fe alloy, a Co alloy, or the like can be used. The thermal conductivity of the soft magnetic layer 26 is, for example, 30 to 100 W / m · K.

The heat insulating layer 28 has a thickness of 2 to 40 nm. The heat conductivity of the heat insulating layer 28 is preferably 0.1 to 10 W / m · K. The thermal conductivity of the heat insulating layer 28 is preferably 1/10 or less of the thermal conductivity of the orientation layer 30 and the thermal conductivity of the soft magnetic layer 26. Further, the thermal conductivity of the heat insulating layer 28 is more preferably 1/100 or less of the thermal conductivity of the alignment layer 30. As the material of the heat insulating layer 28, nonmagnetic materials such as oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ , and ZrO ₂ , nitrides such as AlN, and carbides such as SiC can be used. In the present application, the term “nonmagnetic material” is used to mean a material that is not a ferromagnetic material and is not an antiferromagnetic material.

  The alignment layer 30 is in contact with the lower surface of the recording layer 12. The thickness of the alignment layer 30 is 2 to 40 nm. The alignment layer 30 is preferably made of a metal such as Ru or a material containing a metal as a main component. As the material of the alignment layer 30 other than Ru, a laminated body of Ru and Ta, a CoCr alloy, a metal such as Ti, or a nonmagnetic material such as MgO can be used. The thermal conductivity of the alignment layer 30 is, for example, 30 to 150 W / m · K. In the first embodiment, the concave portion that divides the recording element 12 </ b> A is formed up to a position in the middle of the alignment layer 30 in the thickness direction.

Examples of the filler 32 include oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ , and ZrO ₂ , nitrides such as AlN, carbides such as SiC, C (carbon), Si, Ge, Cu, and Cr. Nonmagnetic metals, resin materials, and the like can be used. The thermal conductivity of the filler 32 is, for example, 0.1 to 110 W / m · K.

  The protective layer 34 has a thickness of 1 to 5 nm. As a material of the protective layer 34, DLC (diamond-like carbon) can be used.

  The lubricating layer 36 has a thickness of 1 to 2 nm. As the material of the lubricating layer 36, PFPE (perfluoropolyether) can be used.

The heating head 18 is arranged close to the upper surface of the magnetic recording medium 16 and is configured to partially heat the magnetic recording medium 16 by irradiating the magnetic recording medium 16 with near-field light. 2 and 3, the heating head 18 includes a light source unit 18A, a waveguide layer 18B, a counter metal layer 18C, and a near-field light gap portion 18D. The light source unit 18A includes a laser diode or the like, and emits emitted light to the upper end portion (end portion opposite to the magnetic recording medium 16) of the waveguide layer 18B. Waveguide layer 18B is a thin film-like member than the width in the circumferential direction D _C of the thickness of the track width direction D _TW of the magnetic recording medium 16, the width of the lower end of the magnetic recording medium 16 side than the width of the upper end It is a thin shape. As a material for the waveguide layer 18B, a dielectric such as SiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , Nb ₂ O ₅ , TiO, and TiO ₂ can be used. A pair of opposing metal layers 18C are provided along both sides of the waveguide layer 18B in the track width direction _DTW . As the material of the opposing metal layer 18C, a metal such as Au, Pd, Pt, Rh, or Ir, an alloy of these metals, or a conductor obtained by adding Al or Cu to these metals or alloys can be used. The near-field light gap portion 18D is installed at the lower end of the waveguide layer 18B. As the material of the near-field light gap portion 18D, the same material as that of the waveguide layer 18B can be used. Width in the track width direction _{D TW} of the near-field light gap portion 18D is 10 to 300 nm. Length in the circumferential direction _{D C} of the near-field light gap portion 18D is 10 to 200 nm. The thickness of the near-field light gap portion 18D in the thickness direction of the magnetic recording medium is 10 to 500 nm. A plurality of arrows below the near-field light gap portion 18D in FIG. 2 schematically show the light that the heating head 18 irradiates the recording element 12A from the near-field light gap portion 18D.

Recording head 20 is also in close proximity to the upper surface of the magnetic recording medium 16, arranged in the vicinity of the side of the feeding direction of the magnetic recording medium 16 in the heating head 18 (the direction indicated by the arrow in the circumferential direction D _C in FIGS. 1 and 3) Has been. The recording head 20 has a single magnetic pole head and is configured to apply a recording magnetic field in a direction perpendicular to the surface of the magnetic recording medium 16 to the recording element 12A. A plurality of arrows below the recording head 20 in FIG. 1 schematically shows a recording magnetic field that the recording head 20 applies to the recording element 12A from a single magnetic pole head. The recording head 20 also includes an auxiliary magnetic pole, an electromagnetic coil, and the like, but illustration and description of the auxiliary magnetic pole, the electromagnetic coil, and the like are omitted.

Reproducing head 22 is also in close proximity to the upper surface of the magnetic recording medium 16, the feed direction opposite to the magnetic recording medium 16 in the recording head 20 (opposite to the direction indicated by the arrow in the circumferential direction D _C in FIGS. 1 and 3) It is arranged in the vicinity.

Next, the operation of the magnetic recording / reproducing apparatus 10 will be described. While driving the magnetic recording medium 16 in the direction of the arrow in the circumferential direction D _C shown in FIG. 1 or the like, the recording elements 12A of the recording target on the basis of the servo information and the like recorded in the servo area of the magnetic recording medium 16 When the heating head 18 irradiates light, the portion of the magnetic recording medium 16 irradiated with light is heated and the temperature rises. Since the recording layer 12 is made of a material having a high thermal conductivity such as an alloy, the recording element 12A targeted for recording is efficiently heated. In addition, a heat insulating layer 28 having a thermal conductivity lower than that of the orientation layer 30 and lower than that of the soft magnetic layer 26 is formed between the orientation layer 30 and the soft magnetic layer 26. Therefore, heat conduction from the heated portion of the recording layer 12 to the soft magnetic layer 26 is suppressed. Therefore, the heated portion of the recording layer 12 is efficiently heated, and the coercivity of the recording element 12A as a recording target is sufficiently reduced. Further, since the recesses between the recording elements 12A are filled with the filler 32 having a thermal conductivity lower than that of the recording element 12A, heat transfer to the other recording elements 12A adjacent to the recording element 12A to be recorded is also achieved. It is suppressed.

  When the recording head 20 applies a recording magnetic field to the heated recording element 12A, the recording element 12A is magnetized or the direction of magnetization is reversed. Thereby, magnetic data is recorded on the recording element 12A of the recording target.

Moreover, while driving the magnetic recording medium 16 in a direction indicated by an arrow in the circumferential direction D _C shown in FIG. 1 or the like, the reproducing head 22, magnetic data is reproduced by detecting a reproducing magnetic field of the recording magnetic field 12A. The magnetic recording / reproducing apparatus 10 can reliably reproduce magnetic data because magnetic data is reliably recorded on the recording element 12A as a recording target.

  As described above, in the magnetic recording / reproducing apparatus 10, even if the soft magnetic layer 26 and the alignment layer 30 having high thermal conductivity are formed under the recording layer 12, the magnetic recording / reproducing apparatus 10 is arranged between the soft magnetic layer 26 and the alignment layer 30. Since the heat insulating layer 28 having a low thermal conductivity is formed, the heated portion of the recording layer 12 having a large magnetic anisotropy energy and a large coercive force can be sufficiently heated to magnetize or reverse the coercive force. Can be easily reduced. Therefore, it is possible to reliably record and reproduce magnetic data on the recording element 12A as a recording target.

Next, a second embodiment of the present invention will be described. While the magnetic recording medium 16 according to the first embodiment is a patterned medium formed by the recording elements 12A is divided at minute intervals track 14 in the circumferential direction D _C in the data area shape, FIG. 5 -7 magnetic recording medium 40 according to the second embodiment as shown, the recording elements 42A is a convex portion of the recording layer 42 is divided at minute intervals in the track width direction D _TW in the data area tracks 14 It is a discrete track medium formed in the shape of. The thickness and material of the recording layer 42 are the same as the thickness and material of the recording layer 12.

  Since other configurations are the same as those of the first embodiment, the same configurations as those in FIGS.

  In the case of the magnetic recording medium 40 that is a discrete track medium, as in the case of the magnetic recording medium 16 that is a patterned medium, the soft magnetic layer 26 and the orientation layer 30 having high thermal conductivity are formed under the recording layer 42. However, since the heat insulating layer 28 having a lower thermal conductivity than these is formed between the soft magnetic layer 26 and the orientation layer 30, the recording layer 42 having a large magnetic anisotropy energy and a large coercive force is formed. It is possible to easily reduce the coercive force to a level at which magnetization or magnetization reversal is possible by sufficiently heating the heating unit. Therefore, it is possible to reliably record and reproduce the magnetic data in the recording target portion of the recording element 42A.

  Next, a third embodiment of the present invention will be described. In the magnetic recording media 16 and 40 according to the first and second embodiments, the recording layers 12 and 42 are formed in a concavo-convex pattern, and the recording elements 12A and 42A have a shape or track 14 corresponding to one recording bit in the data area. In contrast to the patterned media or discrete track media formed in the shape, the magnetic recording medium 50 according to the third embodiment as shown in FIGS. 8 and 9 has the recording layer 52 having a uniform thickness. It is characterized by being a continuous film. The thickness and material of the recording layer 52 are the same as the thickness and material of the recording layers 12 and 42.

  Since other configurations are the same as those of the first and second embodiments, the same reference numerals as those in FIGS.

  In the case of the magnetic recording medium 50 in which the recording layer 52 is a continuous film having a uniform thickness, similarly to the case of the magnetic recording media 16 and 40 that are patterned media or discrete track media, heat is applied below the recording layer 52. Even if the soft magnetic layer 26 and the alignment layer 30 having high conductivity are formed, the heat insulating layer 28 having a lower thermal conductivity is formed between the soft magnetic layer 26 and the alignment layer 30, so that the magnetic By sufficiently heating the heated portion of the recording layer 52 having a large anisotropic energy and a large coercive force, the coercive force can be easily reduced to a level at which magnetization or magnetization reversal can be achieved. Therefore, it is possible to reliably record and reproduce the magnetic data at the recording target portion in the recording layer 52.

  Next, a fourth embodiment of the present invention will be described. In the magnetic recording media 16 and 40 according to the first and second embodiments, the recording layers 12 and 42 and the protective layer 34 are in contact with each other, but as shown in FIG. The magnetic recording medium 60 is characterized in that a thermal conductive layer 62 having a higher thermal conductivity than the recording layer 12 is formed between the recording layer 12 and the protective layer 34. The heat conductive layer 62 is formed exclusively on the recording element 12A. That is, the heat conductive layer 62 is formed in the same pattern at the concave and convex positions as the recording element 12 </ b> A, and the filler 32 is filled between the adjacent heat conductive layers 62. As a material of the heat conductive layer 62, for example, Al or the like can be used.

  Since other configurations are the same as those in the first and second embodiments, the same reference numerals as those in FIGS.

  Similar to the first and second embodiments, in the fourth embodiment as well, the thermal conductivity between the soft magnetic layer 26 and the orientation layer 30 is lower than the thermal conductivity of the orientation layer 30, and the soft magnetic layer Since the heat insulating layer 28 having a thermal conductivity lower than the thermal conductivity 26 is formed, the thermal conduction from the heated portion of the recording layer 12 to the soft magnetic layer 26 is suppressed. Therefore, the predetermined recording target portion in the recording layer 12 can be efficiently heated.

  Further, since the heat conductive layer 62 having a higher thermal conductivity than the recording element 12A is formed on the recording element 12A, variations in the temperature distribution of the recording element 12A can be suppressed.

  FIG. 10 shows an example in which the heat conductive layer 62 is formed on the recording element 12A of the patterned medium similar to the first embodiment, but the discrete track medium as in the second embodiment is shown. Similarly, when the heat conductive layer is formed on the recording element 42A, variation in the temperature distribution of the recording element 42A can be suppressed.

  Next, a fifth embodiment of the present invention will be described.

  In the first, second, and fourth embodiments, the recess between the recording elements 12A and 42A is formed up to a position in the thickness direction of the alignment layer 30, but as shown in FIG. In the magnetic recording medium 70 according to the fifth embodiment, the recesses between the recording elements 12A are formed up to a position in the thickness direction of the heat insulating layer 28, and the alignment layer 30 is completely divided by the recesses. It is characterized by. Note that the recesses between the recording elements 12 </ b> A may be formed up to the boundary between the alignment layer 30 and the heat insulating layer 28. It is preferable that the thermal conductivity of the filler 32 filling the concave portion is lower than the thermal conductivity of the alignment layer 30. The thermal conductivity of the filler 32 is preferably lower than the thermal conductivity of the soft magnetic layer 26.

  Since other configurations are the same as those in the first, second, and fourth embodiments, the same configurations as those in FIGS.

  In the fifth embodiment, since the alignment layer 30 is completely divided by the recesses, heat conduction from the portion directly below the recording target recording element 12A in the alignment layer 30 to other portions of the alignment layer 30 is suppressed. The Therefore, the recording element 12A as a recording target can be heated more efficiently.

  FIG. 11 shows an example of a patterned medium similar to that in the first embodiment. Similarly, in the case of the recording element 42A of the discrete track medium as in the second embodiment, the alignment layer is formed with a recess. By completely dividing 30, heat conduction from the portion immediately below the recording target recording element 42 </ b> A in the alignment layer 30 to the other portion of the alignment layer 30 is suppressed, and the recording target recording element 42 </ b> A can be heated more efficiently. .

  In the first, fourth, and fifth embodiments, the shape of the recording element 12A in the case of patterned media is illustrated as a substantially rectangular shape. However, the shape of the recording element is other than a substantially rectangular shape such as a substantially elliptical shape. It is good also as a shape.

Further, in the first to fifth _{embodiments, SiO 2, Al 2 O 3} , TiO 2, ZrO 2 oxide such as the material of the insulating layer 28, a nitride such as AlN, a non-magnetic carbides such as SiC However, if the thermal conductivity is lower than the thermal conductivity of the alignment layer 30 and lower than the thermal conductivity of the soft magnetic layer 26, other materials may be used as the material of the heat insulating layer 28. May be used.

  In the first to fifth embodiments, examples of the material of the alignment layer 30 include Ru, a stack of Ru and Ta, a CoCr alloy, a metal such as Ti, and a nonmagnetic material such as MgO. Other materials may be used as the material of the alignment layer 30 as long as the material has an effect of improving the orientation of the layers 12, 42, and 52.

In the first to fifth embodiments, the filler 32 includes oxides such as SiO ₂ , Al ₂ O ₃ , TiO ₂ , and ZrO ₂ , nitrides such as AlN, carbides such as SiC, and C (carbon). Examples of materials such as non-magnetic metals such as Si, Ge, Cu, and Cr, and resin materials are exemplified. However, if the non-magnetic material has a lower thermal conductivity than the recording layer 12, the material of the filler 32 is used. Is not particularly limited.

  In the first, second, and fourth embodiments, the recess between the recording elements 12A and 42A is formed up to a position in the middle of the alignment layer 30 in the thickness direction. In the fifth embodiment, recording is performed. The recesses between the elements 12A are formed up to the middle of the heat insulating layer 28 in the thickness direction, or the boundary between the orientation layer 30 and the heat insulating layer 28, but the boundary between the heat insulating layer 28 and the soft magnetic layer 26, Further, the concave portion may be formed up to a position in the middle of the thickness direction of the soft magnetic layer 26. Further, the concave portion may be formed up to the position of the lower surface of the recording layers 12 and 42. Further, the concave portion may be formed up to a position in the middle of the recording layers 12 and 42 in the thickness direction. In this case, the recording layer is a continuous film having a continuous surface on the substrate side. In addition, the recording layer may be a continuous film having a concavo-convex pattern formed following the surface of the concavo-convex pattern substrate, a lower layer such as a soft magnetic layer or an alignment layer. In addition, the recording layer is formed by being divided into the upper surface of the convex portion and the bottom surface of the concave portion, such as a substrate having a concavo-convex pattern, a soft magnetic layer, and an orientation layer, and the portion formed on the upper surface of the convex portion is a recording element. It may be configured.

  In the first, second, fourth, and fifth embodiments, the concave portion between the recording elements 12A and 42A is filled with the filler 32, thereby suppressing the surface irregularities and stabilizing the head flying height. Although heat transfer to the other recording elements 12A and 42A adjacent to the recording elements 12A and 42A to be recorded is suppressed, a sufficiently stable head flying height can be obtained without filling the concave portions with the filler 32. In this case, the recess may be a gap.

  In the first to fifth embodiments, the heating head 18 is configured to heat the recording target portion of the recording layers 12, 42, and 52 using near-field light. , 42, 52 can be heated, for example, the heating head has a laser light source and an objective lens arranged close to the upper surface of the magnetic recording medium 16, 40, 50, 60, 70. A configuration may be adopted in which laser light is focused by an objective lens and irradiated onto the magnetic recording media 16, 40, 50, 60, 70 to heat the recording target portions of the recording layers 12, 42, 52. Alternatively, the recording target portions of the recording layers 12, 42, and 52 may be heated by irradiating with an electron beam.

  In the first to fifth embodiments, the soft magnetic layer 26 is formed in contact with the substrate 24, but another layer may be formed below the soft magnetic layer 26. For example, an antiferromagnetic layer or an underlayer may be formed under the soft magnetic layer 26. Each layer may be composed of a plurality of layers.

  In the first to fifth embodiments, the magnetic recording media 16, 40, 50, 60, 70 are single-sided recording types in which the recording layers 12, 42, 52 are formed on one side of the substrate 24. The present invention can also be applied to a double-sided recording type magnetic recording medium in which recording layers are formed on both sides. In this case, the heating head, recording head, and reproducing head may be installed on both sides of the magnetic recording medium.

[Example of simulation]
Three types of simulation models A, B, and C of the magnetic recording / reproducing apparatus 10 including the magnetic recording medium 50 having the continuous recording layer 52 having a uniform thickness similar to those of the third embodiment were created. In these simulation models A, B, and C, the thickness of the heat insulating layer 28 and the thickness of the alignment layer 30 are different from each other. In addition, the total value of the thickness of the heat insulation layer 28 and the thickness of the orientation layer 30 is equal to 20 nm in all of the simulation models A, B, and C. The simulation models A, B, and C are the same except for the thickness of the heat insulating layer 28 and the thickness of the alignment layer 30. In the simulation models A, B, and C, the protective layer 34 and the lubricating layer 36 of the magnetic recording medium 50 are omitted. In addition, the laser beam is applied to the magnetic recording medium 50 from the heating head.

  For simulation models A, B, and C, a simulation model D having a configuration in which the heat insulating layer 28 is omitted from the magnetic recording medium 50 was created. The thickness of the alignment layer 30 in the simulation model D is 20 nm, which is equal to the total value of the thickness of the heat insulation layer 28 and the thickness of the alignment layer 30 in the simulation models A, B, and C. For configurations other than the heat insulating layer 28 and the alignment layer 30, the simulation model D is equal to the simulation models A, B, and C.

  For simulation models A, B, and C, a simulation model E having a configuration in which the orientation layer 30 is omitted from the magnetic recording medium 50 was created. The thickness of the heat insulation layer 28 of the simulation model E is 20 nm, which is equal to the total value of the thickness of the heat insulation layer 28 and the thickness of the alignment layer 30 of the simulation models A, B, and C. The simulation model E is equal to the simulation models A, B, and C for configurations other than the heat insulating layer 28 and the alignment layer 30.

  Table 1 shows specific configurations of the magnetic recording media of the simulation models A, B, C, D, and E.

  In addition, the conditions regarding the laser beam irradiated to the magnetic recording medium 50 by the heating head were set as follows.

Laser light wavelength: 600 nm
Laser beam spot diameter: 600 nm
Laser power: 10mW
Reflectance at the surface of the magnetic recording medium: 70%

  Since 70% of the power of 10 mW of the laser beam irradiated by the heating head is reflected on the surface of the magnetic recording medium, the effective power of the laser beam applied to the magnetic recording medium is 3 mW.

The spot diameter is a spot diameter on the surface of the recording layer 52. Note that this spot diameter has a peak power of 1 in an energy distribution based on a Gaussian distribution indicating the relationship between the position from the center of the portion irradiated with the laser light and the power of the laser light as illustrated in FIG. The diameter of the position where the power of the laser beam attenuates to 1 / e ² .

Also, the linear velocity in the circumferential direction D _C of the heated portion of the laser beam from the heating head in the magnetic recording medium 50 is irradiated was set to 7.5 m / s. The linear velocity of 7.5 m / s corresponds to the linear velocity of a portion having a radius of 20 mm from the center when the magnetic recording medium rotates at a rotational speed of 3600 rpm, for example.

In addition, Lambert's law was applied to the simulation model. Specifically, the light intensity I when the light having the intensity I ₀ and the wavelength λ ₀ travels the distance d in the medium having the extinction coefficient κ is given by the following equation.

I = I ₀ exp (−4πκd / λ ₀ )

  The extinction coefficients of the recording layer 52, the orientation layer 30, and the soft magnetic layer 26 were set to approximately 4. The extinction coefficients of the heat insulating layer 28 and the substrate 24 were set to approximately 0. Further, the reflectance at the boundary surface of each layer was regarded as zero. That is, the reflection at the boundary surface of each layer in the magnetic recording medium was ignored.

The simulation was executed under the above conditions, and the temperature increase rate (%) of the heated portion of the recording layer 52 was calculated. The rate of temperature increase is the amount of increase in temperature of the heated portion of the recording layer 52 in each simulation model by ΔT (K), and the temperature of the heated portion of the recording layer 52 in the simulation model D in which the heat insulating layer is not formed. Is given by the following equation as ΔT _D (K).

Temperature increase rate (%) = 100 × (ΔT−ΔT _D ) / ΔT _D

  The calculation results are shown in FIG. As shown in FIG. 13, it was found that the heating rate of the heated portion of the recording layer 52 increases as the thickness of the heat insulating layer 28 increases. For example, the simulation model C in which the thickness of the heat insulating layer 28 is 15 nm has a rate of temperature increase of about 100%, and the temperature increase of the heated portion of the recording layer 52 is higher than the simulation model D in which the heat insulating layer is not formed. It was about twice. In the simulation model E in which the alignment layer was not formed and the thickness of the heat insulating layer 28 was 20 nm, the heating rate was higher, but an alignment layer is actually required in order to properly align the recording layer. . By forming the heat insulating layer 28 between the soft magnetic layer 26 and the orientation layer 30, the recording layer can be suitably oriented and the temperature of the heated portion of the recording layer 52 can be significantly increased.

  The present invention can be used in a magnetic recording / reproducing apparatus that records magnetic data on a magnetic recording medium by applying and heating a magnetic field, and magnetically reproduces the magnetic data from the magnetic recording medium.

1 is a cross-sectional side view of a magnetic recording medium schematically showing a schematic structure of a magnetic recording / reproducing apparatus according to a first embodiment of the invention. 1 is a cross-sectional side view along the track width direction of the magnetic recording medium along the line II-II in FIG. FIG. 1 is a plan view of a heating head, a recording head, and a reproducing head viewed from the magnetic recording medium side along the line III-III in FIG. FIG. 1 is a plan view of a magnetic recording medium viewed from the recording head side along line IV-IV in FIG. Sectional drawing along the circumferential direction of the magnetic recording medium which shows typically schematic structure of the magnetic recording / reproducing apparatus concerning 2nd Embodiment of this invention FIG. 5 is a side sectional view of the magnetic recording medium along the track width direction along the line VI-VI in FIG. FIG. 5 is a plan view of the magnetic recording medium viewed from the recording head side along the line VII-VII in FIG. Sectional drawing along the track width direction of the magnetic recording medium which shows typically schematic structure of the magnetic recording / reproducing apparatus concerning 3rd Embodiment of this invention FIG. 8 is a plan view of the magnetic recording medium viewed from the recording head side along the line IX-IX in FIG. Sectional drawing along the circumferential direction of the magnetic recording medium which shows typically schematic structure of the magnetic recording / reproducing apparatus concerning 4th Embodiment of this invention Sectional drawing along the circumferential direction of the magnetic recording medium which shows typically schematic structure of the magnetic recording / reproducing apparatus concerning 5th Embodiment of this invention Energy distribution graph showing the definition of the spot diameter of the laser beam according to the simulation example A graph showing the relationship between the thickness of the heat insulating layer and the heating rate of the recording layer in the same simulation example

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Magnetic recording / reproducing apparatus 12, 42, 52 ... Recording layer 12A, 42A ... Recording element 14 ... Track 16, 40, 50, 60, 70 ... Magnetic recording medium 18 ... Heating head 20 ... Recording head 22 ... Reproducing head 24 ... Substrate 26 ... Soft magnetic layer 28 ... Heat insulation layer 30 ... Orientation layer 32 ... Filler 34 ... Protective layer 36 ... Lubrication layer 62 ... Heat conduction layer

Claims (4)

  A substrate, a soft magnetic layer, a heat insulating layer, an alignment layer, and a recording layer, and these layers are formed on the substrate in this order, and the heat conductivity of the heat insulating layer is that of the alignment layer. A magnetic recording medium having a thermal conductivity lower than that of the soft magnetic layer. In claim 1,
2. The magnetic recording medium according to claim 1, wherein the alignment layer is made of a material containing metal as a main component. In claim 1 or 2,
A magnetic recording medium, wherein the recording layer is formed in a concavo-convex pattern, and a recording element for recording magnetic data is formed in a convex portion of the concavo-convex pattern.   4. The magnetic recording medium according to claim 1, a heating head for heating the recording layer, a recording head for applying a recording magnetic field to the recording layer, and a reproducing magnetic field of the recording layer. And a reproducing head for detecting the magnetic recording / reproducing apparatus.

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