JP2012198951A - Magnetic recording medium and heat-assisted magnetic recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium and a recording method for performing multilayer recording using a heat-assisted magnetic recording method.SOLUTION: The magnetic recording medium includes a plurality of recording layers 23 formed on a substrate 21 in a magnetically separated manner. Each recording layer includes a plurality of magnetic cells 28 that are magnetically mutually separated and, for a magnetic cell that is located closer to the substrate, a magnetic recording medium with higher Curie temperature is used. In recording, the heat-assisted magnetic recording device sequentially performs the recording from the recording layer close to the substrate.

Description

  The present invention relates to information recording with high recording density, and relates to a multilayer magnetic recording medium and a thermally assisted magnetic recording apparatus for thermally assisted magnetic recording.

  As one of information storage systems that support the modern information society, magnetic disk devices mounted on computers and the like are rapidly increasing in recording density, speed, and size. In order to realize a high recording density of the magnetic disk device, the distance between the magnetic disk and the magnetic head is reduced, the crystal grain size constituting the magnetic film of the magnetic recording medium is made fine, the coercive force of the magnetic recording medium. It is necessary to increase (anisotropic magnetic field), speed up signal processing, and the like.

  In order to achieve high recording density, in magnetic recording media, the crystal grain size is reduced, crystal grain boundary regions are provided between the magnetic particles, and noise is reduced by weakening the magnetic coupling between the magnetic particles. Has been planned. However, since the energy for maintaining the recording magnetization is proportional to the volume of the magnetic particles, the resistance to thermal energy decreases when the volume of the magnetic particles is reduced (thermal fluctuation problem).

One method for solving this thermal fluctuation problem is to increase the anisotropic energy _Ku . The anisotropy energy _Ku is a physical property value for stabilizing the magnetization direction, and is determined by the crystal structure of the magnetic particle and the material composing it. Assuming that the environmental temperature is T, the volume of the isolated magnetic particle is v, and the Boltzmann constant is k _B , magnetization reversal due to thermal fluctuations is likely to occur as (K _u · v) / (k _B · T) decreases. That is, if _Ku is increased, thermal fluctuation can be suppressed. Study of K _u is high material have been many. For example, JP 2002-25032, JP-high K _u of superlattice granular of a medium by alternately stacking Co layer and a Pd layer or a Pt layer as shown in JP-2005-190538, or, If a granular medium using CoCr, CoPt, or FePt disclosed in Japanese Patent Application Laid-Open No. 2010-118147 is used, the recording density can be increased.

When a high _Ku medium such as an artificial lattice film or a highly anisotropic alloy film is used, heat-assisted magnetic recording that combines optical recording technology and magnetic recording technology is one of the effective means due to the limitation of head magnetic field strength. One. For example, a recording / reproducing head described in Jpn. J. Appl. Phys. Vol. 38, p. 1839, 1999 is one in which a mechanism for generating light is added to a portion that generates a recording magnetic field. At the time of recording, recording is performed by irradiating light with application of a magnetic field, thereby heating the medium and reducing anisotropic energy (coercivity). According to this method, recording can be easily performed even on a medium having a high coercive force for an ultra-high recording density, which is difficult to record with a conventional magnetic head due to insufficient recording magnetic field. However, to increase the recording density of a magnetic disk device, it is necessary to quickly heat and cool a minute heating area, so the conventional method of focusing laser light used in optical recording with a lens is limited. Occurs. As a method for solving this problem, a method of generating near-field light with metal surface plasmons has been proposed and studied (Optics Japan 2002 Extended Abstracts, 3pA6, 2002, Japanese Patent Application Laid-Open No. 2003-4504, etc.). For reproduction, a GMR (giant magnetoresistive effect) head or a TMR (tunnel magnetoresistive effect) head used in conventional magnetic recording is used.

  Bit Patterned Media (BPM) is also attracting attention as another method for solving the thermal fluctuation problem (J. Appl. Phys., Vol.76, p.6673, 1994, US Patent No. 1). No. 5,820,768, JP-A-10-233015).

This is a method of recording 1 bit per particle. In this method, since one bit is recorded in one regularly arranged magnetic particle (cell), the size of the particle can be made as large as the bit. Therefore, a medium excellent in heat resistance can be provided. However, even in BPM, in order to achieve a surface recording density of 5 Tb / in ² or more, a thermal fluctuation problem is expected due to further narrowing of the magnetic particles. Therefore, it is considered necessary combination of thermally assisted magnetic recording with high K _u material such as FePt. For example, a combination of a bit pattern medium and heat-assisted magnetic recording is described in JP 2010-55722 A and JP 2005-166239 A (US Pat. No. 6,906,879). The former shows a method in which recording bits are separated by an insulator and recording is performed by applying a tunnel current from a tunnel current wiring provided in a magnetic head to raise the temperature of the recording bit. The latter shows a method for realizing multilevel recording (referred to as multilayer recording in this specification) using a pattern medium. Specifically, in a recording medium having two recording layers sandwiching a nonmagnetic layer on a substrate, when the recording layer close to the substrate is the lower layer and the recording layer far from the substrate is the upper layer, the coercive force of the upper layer is lower than the lower layer. Once the head magnetic field and heat are applied, the upper layer and lower layer magnetizations are reversed simultaneously (the lower layer is recorded), and then the upper layer is reversed only by the head magnetic field (upper layer is recorded). It shows how to do it. However, when a high _Ku material is used, the magnetization cannot be reversed only by the head magnetic field, and a multi-level recording method of three or more layers is not described.

Japanese Patent Laid-Open No. 2002-25032 JP 2005-190538 A JP 2010-118147 A Japanese Patent Laid-Open No. 2003-4504 US Pat. No. 5,820,768 JP 10-2333015 JP 2010-55722 A JP 2005-166239 A (US Pat. No. 6,906,879)

Jpn. J. Appl. Phys. Vol. 38, p. 1839, 1999 Optics Japan 2002 Extended Abstracts, 3pA6, 2002 J. Appl. Phys., Vol.76, p.6673 1994

  In view of the above background, the present invention provides a recording medium and a recording method for performing multi-layer recording using a heat-assisted magnetic recording system in response to the problem of realizing ultrahigh recording density.

  The magnetic recording medium of the present invention has two or more recording layers formed on a substrate, each recording layer is magnetically separated by a nonmagnetic layer or the like, and each recording layer is surrounded by a plurality of separation regions. This is a patterned medium composed of magnetic cells. The magnetic cells of the upper and lower recording layers can be arranged so as to overlap in the film thickness direction. Here, the Curie temperature of the magnetic cell of each recording layer is set higher as it is closer to the substrate.

  In order to perform recording on the magnetic recording medium of the present invention by the heat-assisted magnetic recording method, the temperature of a desired magnetic cell is raised to the vicinity of its Curie temperature, and recording is performed by applying a recording magnetic field. At that time, since the temperature of the magnetic cell farther from the substrate than the desired magnetic cell is also raised to the Curie temperature or higher, the magnetization is directed in the same direction as the desired magnetic cell. Next, the magnetic cells farther from the substrate than the desired magnetic cells are sequentially recorded from the one closer to the desired magnetic cell. The recording temperature at the time of recording is set near the Curie temperature of the target magnetic cell, lower than the Curie temperature of the magnetic cell closer to the substrate than the magnetic cell, and farther from the substrate than the magnetic cell. It is higher than the Curie temperature of the magnetic cell.

  The magnetic cell of the pattern medium has an upper and lower side adjacent to the recording layer with respect to the magnetic cell of each recording layer on the surface formed by the thickness direction of the recording medium and the direction of rotation of the recording medium (medium cross section of the same track). The magnetic cells of the recording layer may be arranged without substantially overlapping in the rotation direction of the recording medium. That is, the magnetic cells may be arranged in separate layers in the medium film thickness direction. In the recording method, recording is performed sequentially from the magnetic cell on the substrate side as described above. However, in such a patterned medium, since there are magnetic cells every other layer, the magnetic cells in the upper and lower recording layers overlap. It can be up to half the pattern medium. In addition, the Curie temperature of the patterned medium may be increased toward the side closer to the substrate in the magnetic cell located at the same position on the surface (medium plane) formed by the medium rotation direction and the medium radial direction.

  Furthermore, in view of the fact that the reproduction signal becomes weaker as the magnetic cell on the substrate side, the magnetic cell of the recording layer closer to the substrate may use a patterned medium having a larger saturation magnetization value than the magnetic cell of the recording layer far from the substrate. Good. For the same reason, a patterned medium in which the volume of the magnetic cell of the recording layer close to the substrate is larger than that of the magnetic cell of the recording layer far from the substrate may be used.

  Further, when the recording medium is limited to a two-layer medium, the recording layer close to the substrate may be a conventional granular perpendicular magnetic recording film, and the recording layer far from the substrate may be a pattern film.

  According to the multilayer magnetic recording medium and recording method for heat-assisted magnetic recording of the present invention, it is possible to realize an ultrahigh recording density.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

FIG. 3 is a schematic diagram illustrating a cross-sectional structure example of a patterned medium according to the first embodiment. FIG. 3 is a diagram illustrating a manufacturing process of the patterned medium according to the first embodiment. FIG. 3 is a diagram illustrating a manufacturing process of the patterned medium according to the first embodiment. FIG. 3 is a diagram illustrating a manufacturing process of the patterned medium according to the first embodiment. FIG. 3 is a diagram illustrating a manufacturing process of the patterned medium according to the first embodiment. FIG. 3 is a diagram illustrating a manufacturing process of the patterned medium according to the first embodiment. FIG. 3 is a diagram illustrating a manufacturing process of the patterned medium according to the first embodiment. Figure shows the temperature dependence of the anisotropy field H _k of the perpendicular magnetic recording medium of the present invention. 1 is a schematic diagram showing an example of the structure of a magnetic disk device. FIG. 3 is a diagram illustrating a configuration example of a heat-assisted magnetic recording head. The figure which showed the procedure which records on a recording medium with three recording layers. The figure which showed the procedure which records on a recording medium with three recording layers. The figure which showed the procedure which records on a recording medium with three recording layers. The figure which showed the procedure which records on a recording medium with three recording layers. Media model diagram for computer simulation. The figure which shows the recording procedure using computer simulation. The figure which shows the recording procedure using computer simulation. The figure which shows the recording procedure using computer simulation. The figure which shows the recording procedure using computer simulation. The figure which shows a computer simulation result. The figure which shows a computer simulation result. The figure which shows a computer simulation result. The figure which shows a computer simulation result. The figure which shows an example of a recording magnetization pattern and a reproduction | regeneration waveform. FIG. 6 is a schematic diagram illustrating an example of a cross-sectional structure of a patterned medium according to the second embodiment. FIG. 6 is a schematic diagram illustrating an example of a cross-sectional structure of a patterned medium according to the second embodiment. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 2. Media model diagram for computer simulation. The figure which shows the recording procedure using computer simulation. The figure which shows the recording procedure using computer simulation. The figure which shows a computer simulation result. The figure which shows a computer simulation result. The figure which shows the recording procedure using computer simulation. The figure which shows the recording procedure using computer simulation. The figure which shows the recording procedure using computer simulation. FIG. 6 is a schematic diagram illustrating a cross-sectional structure example of a patterned medium according to a third embodiment. FIG. 6 is a schematic diagram illustrating a planar structure example of a patterned medium according to a third embodiment. FIG. 6 is a schematic diagram illustrating a cross-sectional structure example of a patterned medium according to a third embodiment. FIG. 6 is a schematic diagram illustrating a cross-sectional structure example of a patterned medium according to a fourth embodiment. FIG. 10 is a diagram illustrating an example of a recording pattern of a pattern medium according to a fourth embodiment. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 4. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 4. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 4. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 4. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 4. FIG. 6 is a diagram showing a process for manufacturing a patterned medium of Example 4.

  Embodiments of the present invention will be described below with reference to the drawings.

[Example 1]
FIG. 1 is a schematic diagram of a patterned medium according to Embodiment 1 of the present invention. The figure shows a surface (cross-sectional view) formed by the film thickness direction z of the medium and the medium traveling direction (down track direction) x. In the figure, the medium comprises a non-magnetic substrate 21, an underlayer 22, a multilayer recording layer 24 in which n perpendicular magnetic recording layers 23 are stacked, and a protective layer 25. Each magnetic cells 28 of each vertical magnetic recording layer 23, FePt alloy film, CoCr alloy film, CoPd alloy film, CoPt alloy film, SmCo alloy film, Co / Pd multilayer film, the high K _u vertical such Co / Pt multilayer film It is made of a magnetic anisotropic material. The magnetic cells 28 in each layer are separated by a nonmagnetic filling layer 26. Nonmagnetic filler layer, for example NiTi, SiO _2, alumina (Al ₂ O _3, etc.), spin-on-glass, CrTi, oxide (tungsten oxide, tantalum oxide, etc.), made of a nitride or the like. Further, each layer of the perpendicular magnetic recording layer is magnetically separated and independent by a nonmagnetic layer 27 such as MgO, Ru, SiO ₂ , Al ₂ O ₃ , Fe ₃ O ₄ , oxide, or nitride. That is, the magnetic cells 28 above and below each recording layer are magnetically separated and independent, and are separate bits.

Next, the manufacturing method of the patterned medium of the present embodiment will be described with reference to FIGS. 2A to 2F in the case of three perpendicular magnetic recording layers. First, as shown in FIG. 2A, an underlayer 22 and a first perpendicular magnetic recording layer 231 are sequentially formed on a nonmagnetic substrate 21 by a sputtering method or the like. Further, the nonmagnetic layer 27, the second perpendicular magnetic recording layer 232, the nonmagnetic layer 27, and the third perpendicular magnetic recording layer 233 are formed in this order until there are a total of three perpendicular magnetic recording layers, on which a protective layer is formed. 29 is formed. Here, the Curie temperature of each perpendicular magnetic recording layer can be changed by adding Ni, Ag, Cu or the like. Alternatively, it can be realized by a combination of the above high _Ku materials. Subsequently, a resist pattern 30 is formed on the protective layer 29 as shown in FIG. 2B. Subsequently, as shown in FIG. 2C, the resist pattern is transferred to the recording layer by etching using an inert gas such as Ar ions. Subsequently, the remaining resist 30 and protective layer 29 are removed using reactive ion etching. At this time, by using hydrogen gas, the recording layer surface can be removed without alteration. Subsequently, using sputtering or the like as shown in FIG. 2D, the groove is filled with a material to be the nonmagnetic filling layer 26 so as to cover the pattern, and as shown in FIG. 2E, reactive ion etching or inert gas is used. The surface of the nonmagnetic filling layer 26 is planarized by ion etching or the like used. Subsequently, the nonmagnetic filling layer is shaved by ion etching using an inert gas, and finally, as shown in FIG. 2F, a protective layer 25 and a lubricating layer (not shown) can be formed to produce a patterned medium.

  More specifically, for example, a glass substrate having a diameter of 65 mm is used as the nonmagnetic substrate 21. On the glass substrate, 10 nm of MgO is added as the underlayer 22, and Ni is added to 4 nm of FePt as the first perpendicular magnetic recording layer 231 thereon. Here, the Fe element is 50 atomic%, the Pt element is 45 atomic%, and the Ni element is 5 atomic%. Subsequently, 2 nm of MgO is stacked as the nonmagnetic layer 27 and 4 nm of FePt is stacked as the second perpendicular magnetic recording layer 232. Here, in order to make the Curie temperature of the second perpendicular magnetic recording layer 232 lower than the Curie temperature of the first perpendicular magnetic recording layer 231, the Fe element is 45 atomic%, the Pt element is 45 atomic%, and the Ni element is 10 atomic%. Similarly, a nonmagnetic layer and a third perpendicular magnetic recording layer 233 are stacked. In order to make the Curie temperature of the third perpendicular magnetic recording layer 233 lower than the Curie temperature of the second perpendicular magnetic recording layer 232, Fe element is 40 atomic%, Pt element is 45 atomic%, and Ni element is 15 atomic%. It was. The protective layer 29 is made of 4 nm sputtered carbon. Next, the imprint resist pattern 30 is formed using the imprint apparatus. The total thickness of the resist pattern 30 is 70 nm, the height of the pattern 301 is 60 nm, and the resist residue 302 is 10 nm. The resist pattern can also be formed by photolithography using an exposure apparatus.

  Next, etching is performed in oxygen gas using a reactive ion etching apparatus, and the resist residue 302 and the protective layer 29 in the recesses of the resist pattern are removed. Next, using the resist as a mask, the recording layer is etched using an Ar ion beam. Next, using a reactive ion etching apparatus, etching is performed in hydrogen gas, and the remaining resist and the protective layer 29 are removed. Next, NiTi to be a nonmagnetic filling layer is formed. Next, the unevenness on the surface of the nonmagnetic filling layer is reduced to 2 nm or less using an etching apparatus. Next, the nonmagnetic filling layer is etched with an Ar ion beam using an ion beam etching apparatus to remove the nonmagnetic filling layer in the recording portion. Fe is detected by secondary ion mass spectrometry, and the etching is terminated when the detected amount increases to more than twice the background. Next, a carbon protective layer 25 and a lubricating layer (not shown in the figure) are formed using a sputtering apparatus.

  As yet another manufacturing method, first, a pattern is drawn on a substrate by lithography, and an underlayer and a perpendicular magnetic recording layer are sequentially formed on the resist on the pattern by a sputtering method or the like. Further, a total of n layers are formed in the order of the nonmagnetic layer, the underlayer, and the perpendicular magnetic recording layer, and a protective layer is formed thereon. Subsequently, a pattern is formed by removing the resist. Alternatively, a recording layer is first laminated on a substrate, a pattern is drawn on the recording layer by lithography, the recording layer is etched by a lithographic mask, and the resist is removed to form a pattern. Subsequently, using sputtering or the like, the groove is filled with a nonmagnetic material so as to cover the pattern, and then the surface of the nonmagnetic filling layer is formed using reactive ion etching or ion etching using an inert gas. Flatten. Subsequently, the nonmagnetic filling layer is shaved by ion etching using an inert gas, and finally, a protective layer and a lubricating layer are formed to produce a patterned medium.

  As another manufacturing method, it can also be manufactured by changing the characteristics of the irradiated region by ion irradiation through a mask. In an example of a patterned medium manufacturing process by ion irradiation, the gap is formed of a magnetic material that does not affect the perpendicular magnetic characteristics of the magnetic pattern.

FIG. 3 is a diagram showing the temperature dependence of the anisotropic magnetic field H _k of each recording layer. This is a result obtained by laminating only one MgO underlayer and FePtNi recording layer on the substrate and measuring the MH loop and the torque curve at different temperatures. Specifically, for example, the temperature characteristic of the saturation magnetization M _s is measured by measuring the MH loop with a VSM (Vibrating Sample Magnetometer) or the like. Next, the temperature characteristics of K _u, in the magnetic anisotropy torque meter or the like, by changing the direction of the magnetic field by rotating the electromagnet, determined by measuring the torque acting on the direction of the medium. The temperature characteristic of H _k is _{obtained from} the equation H _k (T) = 2 × K _u (T) / M _s (T) (T is temperature).

The composition of the FePtNi recording layer was the above three types. That is, a recording layer of Fe element 50 atom%, Pt element 45 atom%, Ni element 5 atom%, Fe element 45 atom%, Pt element 45 atom%, Ni element 10 atom%, and Fe element 40 atom %, Pt element 45 atom%, Ni element 15 atom%. Curve 401 is the temperature dependency of the H _k in the first vertical magnetic recording layer 231 of the multi-layer medium prepared in the step of FIG. 2F Figures 2A, curve 402 the temperature dependence of the H _k in the second vertical magnetic recording layer 232 Curve 403 corresponds to the temperature dependence of H _k in the third perpendicular magnetic recording layer 233, respectively. In FIG. 3, T _c1 (= 720 K) is the Curie temperature of the first perpendicular magnetic recording layer 231, T _c2 (= 650 K) is the Curie temperature of the second perpendicular magnetic recording layer 232, and T _c3 (= 590 K) is the third. Of the perpendicular magnetic recording layer 233. Here, when the magnetic cell of each layer is heated to around the Curie temperature and a recording magnetic field is applied, the magnetization is reversed and recorded. Further, there is a relationship of T _c3 <T _c2 <T _c1 , and it is desirable that there is a sufficient temperature difference between T _c of the upper and lower recording layers.

The magnetic recording medium of this embodiment manufactured in this way includes a plurality of recording layers that are magnetically separated and stacked on a disk-shaped substrate, and each recording layer is a plurality of magnetically separated layers. Including magnetic cells. The magnetic cells of each recording layer are regularly arranged in the direction of rotation of the substrate in a state where they overlap each other in the direction perpendicular to the film surface, and the Curie temperature of the magnetic cells contained in the plurality of recording layers is in the recording layer close to the substrate. The included magnetic cells are set higher.
Next, a recording method when there are three perpendicular magnetic recording layers will be described.

  FIG. 4 is a schematic diagram showing a structural example of a magnetic disk device. Usually, one or several magnetic disks 15 are mounted in the drive of the magnetic disk device. The magnetic disk 15 of this example is rotationally driven in the direction of the arrow 10. As shown in the enlarged view of FIG. 4, the magnetic head 12 at the rear end of the magnetic head slider 11 fixed to the front end of the carriage 13 accesses an arbitrary track by a voice coil motor 14, and a magnetic disk (medium). Record and play back information.

  FIG. 5 is a schematic cross-sectional view showing a configuration example of a recording head used in the heat-assisted magnetic recording apparatus. FIG. 5 shows a cross-sectional structure around the recording head when the recording head 100 and the reproducing head 130 are cut along a plane parallel to the film thickness direction z (vertical direction in the figure) and the medium running direction x. .

  The recording head 100 includes an upper magnetic pole 101, a lower magnetic pole 102, and a main magnetic pole 103. The upper magnetic pole and the lower magnetic pole are connected by the connecting portion 104. Further, a conductor pattern 105 is formed on the upper magnetic pole 101 in a spiral shape, and both ends thereof are drawn out and connected to a magnetic head driving circuit. One end of the main magnetic pole 103 is connected to the upper magnetic pole 101. The upper magnetic pole 101, the lower magnetic pole 102, the main magnetic pole 103, the connection portion 104, and the conductor pattern 105 constitute an electromagnet as a whole, and a recording magnetic field is applied to the magnetic recording medium 120 near the tip of the main magnetic pole 103 by a driving current. Is done. Further, the recording head 100 is provided with a near-field light generator 110 sandwiched between the upper magnetic pole 101 and the lower magnetic pole. That is, since the recording head 100 moves in the direction of the arrow 134 with respect to the magnetic recording medium 120, it can be seen that the near-field light generator 110 is provided at the head leading edge 135. When the near-field light generating unit 110 irradiates a laser beam 112 having a wavelength of, for example, 720 nm from the laser light source 111 and passes through the optical waveguide 113 and reaches the metal scatterer 114 provided in the vicinity of the main magnetic pole on the recording medium facing surface, Near-field light 115 is generated from the tip of the scatterer 114 to heat the magnetic recording medium 120. Recording is performed by applying a recording magnetic field to the heated magnetic recording medium 120. The recording head having the above structure can be manufactured by a thin film formation process and a lithography process. On the other hand, the read head 130 is composed of a GMR (giant magnetoresistive effect) element or a TMR (tunnel magnetoresistive effect) element 133 sandwiched between an upper shield 131 and a lower shield 132.

  6A to 6D are diagrams showing a procedure for recording on the patterned medium of the present embodiment having three recording layers. The arrows in the three-layer magnetic cell that overlap vertically indicate the direction of magnetization (magnetic moment). FIG. 6A shows the initial recording magnetization state, and it is assumed that the magnetization of all layers is downward. For recording, the magnetization of the magnetic cell 136 of the first perpendicular magnetic recording layer (lowermost layer) faces upward, the magnetization of the magnetic cell 137 of the second perpendicular magnetic recording layer (middle layer) faces downward, and the third perpendicular magnetic recording layer ( It is assumed that the magnetization of the magnetic cell 138 in the uppermost layer is reversed upward.

_Assuming that the recording temperature is T _rec , first, T _rec is in the vicinity of T _c1 , the laser power is adjusted so that the condition of T _c2 <T _rec is satisfied, the medium is irradiated with near-field light, and an upward recording magnetic field is generated. Apply. The recording magnetic field intensity may be set to an optimum magnetic field intensity that does not reverse magnetization even when applied at room temperature. When recording is performed under these conditions, as shown in FIG. 6B, the magnetic cells 136 to 138 of all the perpendicular magnetic recording layers are inverted in magnetization upward. Next, as shown in FIG. 6C, the medium is heated so that T _rec is in the vicinity of T _c2 and T _c3 <T _rec <T _c1 is satisfied, and a downward recording magnetic field is applied. As a result, the magnetization of the magnetic cell 136 of the first perpendicular magnetic recording layer is not reversed, but the magnetization of the magnetic cells 137 and 138 of the second and third perpendicular magnetic recording layers is reversed downward. Finally, as shown in FIG. 6D, the medium is heated so that T _rec is in the vicinity of T _c3 and T _rec <T _c2 is satisfied, and an upward recording magnetic field is applied. Then, the magnetization of the magnetic cell 138 of the third perpendicular magnetic recording layer is reversed upward. This completes recording. Comparing FIG. 6A and FIG. 6D, the magnetization of the magnetic cell 136 of the first perpendicular magnetic recording layer is upward, the magnetization of the magnetic cell 137 of the second perpendicular magnetic recording layer is downward, and the magnetization of the third perpendicular magnetic recording layer The magnetization of the cell 138 is reversed and recorded. Here, recording is completed by rotating the magnetic disk three times.

  The same recording method is used when recording other layers. That is, the magnetic disk is rotated up to three times.

  The results of verifying recording on the medium of the present embodiment by computer simulation means using micromagnetics are shown below.

The Landau-Lifshitz-Gilbert equation (J. Appl. Phys. 75 (2), 15 Jan. 1994) was used for the calculation. As shown in FIG. 7, the medium has a bit pattern in which the bit length is 20 nm, the magnetic cell diameter is 12 nm, the perpendicular magnetic recording layers 231, 232, and 233 are 4 nm thick, and the nonmagnetic layer 27 is 2 nm thick. A medium was assumed. The temperature characteristics of H _k were the same as those in FIG. The head magnetic field was simulated using a commercially available three-dimensional magnetic field analysis program JMAG. The effective head magnetic field (H _x ² + H _y ² ) ^1/2 + | H _z | applied to the center of the medium film is a position 20 nm away from the head leading edge (corresponding to the light irradiation position), and all layers The thickness was about 8 kOe at the center of the thickness. The magnetic spacing between the head and the medium was 6 nm. The temperature profile assumed a Gaussian distribution with a half-value width of 15 nm at the center of the thickness of each layer.

FIG. 8A to FIG. 8D are diagrams showing the recording procedure of the computer simulation. First, as shown in FIG. 8A, all the magnetizations of the medium were initialized to the upward magnetization state. Finally, the magnetization of the magnetic cell 136 of the first perpendicular magnetic recording layer is downward, the magnetization of the magnetic cell 137 of the second perpendicular magnetic recording layer is upward, and the magnetization of the cell 138 of the third perpendicular magnetic recording layer is downward. Will be recorded. First, as shown in FIG. 8B, the near-field light 115 is irradiated to a position 20 nm away from the head leading side 135 of the main magnetic pole 103 to raise the temperature to 730 K, which is a value in the vicinity of T _c1 . A head magnetic field 139 is applied to make the magnetizations downward in all three layers. Next, the temperature is raised to 660 K (lower than T _c1 ) which is a value near T _c2 , an upward magnetic field is applied, and the second and third perpendicular magnetic recording layers are applied as shown in FIG. 8C. The magnetization of the magnetic cells 137 and 138 is made upward. Finally, the temperature is raised to 580 K, which is a value near T _c3 , and a downward magnetic field is applied, so that only the third magnetic cell 138 faces downward as shown in FIG. 8D.

  9A to 9D show simulation results. The figure is a plan view formed by the downtrack direction x and the crosstrack direction y, and shows the first to third magnetic recording layers. Further, the number of planar magnetic cells was calculated as 32 × 8, but the figure shows only the vicinity of recording. In the figure, ◯ means that the magnetization of the magnetic cell is facing upward. ● indicates that the magnetization of the magnetic cell faces downward. FIG. 9A shows the initial magnetization state. All the magnetizations are facing up. FIG. 9B shows the result of increasing the temperature of the tenth magnetic cell from the top to the left up to 730 K and applying a downward magnetic field. As a result, the magnetization was downward in all layers. FIG. 9C shows the result of increasing the temperature to 660 K and applying an upward magnetic field. As a result, the magnetization of the magnetic cells 137 and 138 of the second and third perpendicular magnetic recording layers became upward, but the magnetization of the first magnetic cell 136 remained downward. FIG. 9D shows the result of increasing the temperature to 580 K and applying a downward magnetic field. As a result, the magnetization of the magnetic cell of the third perpendicular magnetic recording layer became downward. From the above, it was confirmed that the first magnetic cell 136 was recorded downward, the second magnetic cell 137 was upward, and the third magnetic cell 138 was recorded downward by this recording method.

  FIG. 10 shows an example of the recording magnetization pattern and reproduction signal of the multilayer medium recorded by the recording method of this embodiment. The figure assumes three recording layers. In the case of three layers, there are two cubes (= 8) of combinations of magnetization patterns of magnetic cells overlapping in the direction perpendicular to the film surface of the first to third perpendicular magnetic recording layers. Therefore, assuming that the ratio of the signal magnitude of the first layer to the third layer reproduced by the reproducing MR element 133 of FIG. 5 is 1: 3: 5, there are eight types a to h as shown in FIG. Different reproduction signals are detected for each recording magnetization pattern. Accordingly, the magnetization information of each layer can be determined based on the magnitude of the reproduction signal.

[Example 2]
In the first embodiment, the magnetic disk is rotated by the maximum number of times corresponding to the number n of layers for recording, so the recording time is n times that of a normal magnetic disk device. Therefore, in the second embodiment, a method for reducing the recording time from that of the first embodiment and setting the maximum recording time to n / 2 times for the even layer and (n + 1) / 2 for the odd layer will be described.

FIG. 11 is a schematic cross-sectional view (same track) of the patterned medium of this example. Two perpendicular magnetic recording layers were used. In the figure, the medium includes a nonmagnetic substrate 21, an underlayer 22, a first perpendicular magnetic recording layer 231, a nonmagnetic layer 27, a second perpendicular magnetic recording layer 232, and a protective film 25. The cells in each layer are separated by a nonmagnetic filling layer 26. Each cell 28 of the perpendicular magnetic recording layer 231, 232, FePt alloy film, CoCr alloy film, CoPd alloy film, CoPt alloy film, SmCo alloy film, Co / Pd multilayer film, Co / Pt multilayer film or the like, a high K _u Made of perpendicular magnetic anisotropic material. As the material of the non-magnetic filler layer 26, for example NiTi, SiO _2, alumina (Al ₂ O _3, etc.), spin-on-glass, CrTi, oxide (tungsten oxide, tantalum oxide, etc.), there is a nitride or the like. Further, each layer of the perpendicular magnetic recording layer is magnetically separated and independent by a nonmagnetic layer 27 such as MgO, Ru, SiO ₂ , Al ₂ O ₃ , Fe ₃ O ₄ , oxide, or nitride. That is, the upper and lower magnetic cells of each layer are magnetically separated and independent, and are different bits.

  In the multilayer magnetic recording medium of Example 2, as shown in the figure, the magnetic cells of the upper and lower recording layers adjacent to the recording layer are substantially aligned with the magnetic cells of each recording layer in the direction of rotation of the recording medium. It is characterized by arranging without overlapping. More specifically, the size of the upper and lower magnetic cells 28 is half the bit length, and the center of the magnetic cell is shifted by a distance of half the bit length. Furthermore, if the size of the upper and lower magnetic cells is made half or less of the bit length as shown in FIG. 12, the upper and lower magnetic cells can be recorded separately and independently.

  Next, the manufacturing method of the patterned medium of a present Example is demonstrated using FIG. 13A to FIG. 13J. First, as shown in FIG. 13A, a glass substrate having a diameter of 65 mm, for example, is used as the nonmagnetic substrate 21. On the glass substrate, 10 nm of MgO is added as the underlayer 22 and Ni is added to 4 nm of FePt as the first perpendicular magnetic recording layer 231 to be laminated. Here, the Fe element is 50 atomic%, the Pt element is 45 atomic%, and the Ni element is 5 atomic%. A protective layer 29 is formed thereon.

  Next, as shown in FIG. 13B, an imprint resist pattern is formed using an imprint apparatus. The total thickness of the resist 30 is 70 nm, the height of the pattern 301 is 60 nm, and the resist residue 302 is 10 nm. The resist pattern can also be formed by photolithography using an exposure apparatus.

  Next, as shown in FIG. 13C, etching is performed in oxygen gas using a reactive ion etching apparatus, and the resist residue 302 and the protective layer 29 in the recesses of the resist pattern are removed. Next, using the resist as a mask, the recording layer is etched using an Ar ion beam. Next, using a reactive ion etching apparatus, etching is performed in hydrogen gas, and the remaining resist 30 and protective layer 29 are removed. Next, as shown in FIG. 13D, NiTi to be the nonmagnetic filling layer 26 is formed. Next, the unevenness on the surface of the nonmagnetic filling layer is reduced to 2 nm or less using an etching apparatus, and further, as shown in FIG. 13E, the nonmagnetic filling layer is etched with an Ar ion beam using an ion beam etching apparatus. The unfilled layer of the recording part is removed. Fe is detected by secondary ion mass spectrometry, and the etching is terminated when the detected amount increases to more than twice the background.

  Subsequently, as shown in FIG. 13F, 2 nm of MgO is formed as the nonmagnetic layer 27, and 4 nm of FePt is stacked thereon as the second perpendicular magnetic recording layer 232. Here, since the Curie temperature of the second perpendicular magnetic recording layer 232 is the same as the Curie temperature of the first perpendicular magnetic recording layer 231, the Fe element is 50 atomic%, the Pt element is 45 atomic%, and the Ni element is 5 atomic%. Atomic%. A protective layer 29 is formed thereon. Subsequently, as shown in FIG. 13G, an imprint resist pattern is formed using an imprint apparatus. The total thickness of the resist 30 is 70 nm, the height of the pattern 301 is 60 nm, and the resist residue 302 is 10 nm. The resist pattern can also be formed by photolithography using an exposure apparatus.

  Next, as shown in FIG. 13H, using a reactive ion etching apparatus, etching is performed in oxygen gas to remove the resist residue 302 and the protective layer 29 in the recesses of the resist pattern. Next, using the resist as a mask, the recording layer is etched using an Ar ion beam. Next, using a reactive ion etching apparatus, etching is performed in hydrogen gas, and the remaining resist 30 and protective layer 29 are removed. Next, as shown in FIG. 13I, NiTi to be the nonmagnetic filling layer 26 is formed. Next, the unevenness of the surface of the nonmagnetic filling layer 26 is reduced to 2 nm or less using an etching apparatus, and the nonmagnetic filling layer 26 is etched with an Ar ion beam using an ion beam etching apparatus, so that the nonmagnetic property of the recording part Remove the packed bed. Finally, as shown in FIG. 13J, a protective layer 25 and a lubricating layer (not shown) are formed using a sputtering apparatus.

  The magnetic recording medium of this embodiment manufactured in this way includes a plurality of recording layers that are magnetically separated from each other and stacked on a disk-shaped substrate. The recording layer includes a plurality of magnetic cells magnetically separated from each other, and the magnetic cells of the recording layers adjacent to each other are regularly arranged in the direction of rotation of the substrate so as not to overlap each other in the direction perpendicular to the film surface. .

  Next, the result of verifying the recording on the medium of this embodiment by computer simulation means using micromagnetics will be shown.

The conditions of the head and temperature distribution are the same as in the first embodiment. As shown in FIG. 14, the medium has a bit length of 20 nm, a magnetic cell size of 10 nm (magnetic cell size = bit length / 2), the perpendicular magnetic recording layers 231 and 232 have a thickness of 4 nm, and the nonmagnetic layer 27 A bit pattern medium with a thickness of 2 nm was assumed. Temperature characteristics of the H _k was set to a temperature characteristic 401 of H _k of the first vertical magnetic recording layer shown in FIG. 3 in all layers.

FIG. 15A and FIG. 15B show the calculation procedure. In the medium of this example, first, as shown in FIG. 15A, all the magnetizations of the medium were initialized to an upward magnetization state. Thereafter, the temperature of the magnetic cell 136 to be reversed is raised to a value of 730 K near T _c1 and a downward magnetic field is applied to reverse the magnetization downward as shown in FIG. 15B. Since the medium of this embodiment has two layers and the magnetic cells of the upper and lower perpendicular magnetic recording layers are arranged so as not to overlap each other in the direction perpendicular to the film surface, only one recording process is performed as in the case of one layer. To complete the recording. The calculation results are shown in FIGS. 16A and 16B. FIG. 16A is a diagram showing an initial state. Magnetization is upward in both the upper and lower layers. FIG. 16B shows the result of applying a downward magnetic field by raising the temperature of the fifth magnetic cell from the top left to the fourth perpendicular magnetic recording layer to 730K. As a result, it was confirmed that the magnetization of the first perpendicular magnetic recording layer was reversed, but the second perpendicular magnetic recording layer was entirely upward without being affected.

  From the above, it is clear that the recording time of Example 2 is half that of Example 1, and the effect of Example 2 was confirmed.

  In the above embodiment, two layers are assumed. However, in the case of three or more layers, the Curie temperatures of the odd and even layers must be increased as they are closer to the substrate side.

FIG. 17A to FIG. 17C are schematic views showing a procedure for recording on a patterned medium when the multilayer magnetic recording medium has three layers. In the figure, as in FIG. 6A and the like, the arrow in the cell indicates the direction of magnetization (magnetic moment). Assume that recording is performed by inverting the magnetization of the recording cell 136 of the first perpendicular magnetic recording layer downward and the magnetic cell of the magnetic cell 138 of the third perpendicular magnetic recording layer upward. The Curie temperature of the first perpendicular magnetic recording layer 231 including the magnetic cell 136 is T _c1 . The upper magnetic cell 138 of the magnetic cell 136 is not included in the second perpendicular magnetic recording layer 232 but in the third perpendicular magnetic recording layer 233. When the Curie temperature of the third perpendicular magnetic recording layer and T _c3, there is relation of T _c1> T _c3, it is desirable that the Curie temperature of each layer is sufficiently temperature difference. However, when magnetic cells 136 and 138 are sufficiently separated, T _c1 and T _c3 may be close values. The reason for this will be shown later. Here, the Curie temperature T _c2 of the second perpendicular magnetic recording layer 232 is not limited to T _c1 and T _c3 . This is because the magnetic cell of the second perpendicular magnetic recording layer 232 is magnetically separated and independent from the magnetic cells of the first and third perpendicular magnetic recording layers 231 and 233.

As shown in FIG. 17A, an initial recording magnetization state is assumed. The magnetizations of the magnetic cell 136 of the first perpendicular magnetic recording layer and the magnetic cell 138 of the third perpendicular magnetic recording layer are both upward. First, if the recording temperature is T _rec , T _rec is in the vicinity of T _c1 , the laser power is adjusted so that the condition of T _c3 <T _rec is satisfied, and the medium is irradiated with near-field light. Apply. The recording magnetic field intensity may be set to an optimum magnetic field intensity that does not reverse magnetization even when applied at room temperature. When recording is performed under this condition, as shown in FIG. 17B, the magnetizations of the magnetic cells 136 and 138 of the first perpendicular magnetic recording layer and the third perpendicular magnetic recording layer are reversed in the downward direction. Next, when the recording temperature T _rec is in the vicinity of T _c3 , the medium is heated so that T _rec <T _c1 is satisfied, and an upward recording magnetic field is applied. As a result, as shown in FIG. 17C, the magnetization of the magnetic cell 136 of the first perpendicular magnetic recording layer is not reversed, but the magnetization of the magnetic cell 138 of the third perpendicular magnetic recording layer is reversed upward. This completes recording. That is, the magnetization of the magnetic cell 136 of the first perpendicular magnetic recording layer is reversed and the magnetic cell of the magnetic cell 138 of the third perpendicular magnetic recording layer is reversed and recorded. Here, the recording is completed by rotating the magnetic disk twice. Therefore, the recording time is reduced as compared with the first embodiment.

Next, the reason why T _c1 and T _c3 may be close values when the magnetic cells 136 and 138 are sufficiently separated from each other is shown. When an appropriate distance is set between the upper and lower magnetic cells, a temperature difference occurs between the upper and lower magnetic cells. Thus, for example, the temperature of the magnetic cell 138 is raised to the Curie temperature, but the magnetic cell 136 can be sufficiently lower than the Curie temperature. When the magnetizations of the magnetic cells 136 and 138 are both turned downward from the initial state of FIG. 17A as shown in FIG. 17B, the laser power may be increased so that the temperature of the magnetic cell 136 is close to the Curie temperature. Further, as shown in FIG. 17C, in order to reverse only the magnetization of the magnetic cell 138 upward, the laser power may be lowered so that only the temperature of the magnetic cell 138 is close to the Curie temperature. In this way, when the upper and lower magnetic cells are sufficiently separated from each other, a temperature difference occurs in the film thickness direction, so that the Curie temperature can be made close.

[Example 3]
The third embodiment shows an example for preventing the output signal during reproduction from deteriorating as the distance from the head increases. Here, an example in which the present embodiment is applied to the patterned medium of the second embodiment will be described. FIG. 18 shows a surface (cross-sectional view) formed by the film thickness direction of the patterned medium and the medium running direction according to this example. The number of layers was set to 2 for simplicity. FIG. 19 is a schematic plan view seen from a plane formed by the medium running direction of the patterned medium and the direction perpendicular to the track (medium radial direction).

  The magnetic cell 136 is a magnetic cell of the first perpendicular magnetic recording layer 231, and the magnetic cell 137 is a magnetic cell of the second perpendicular magnetic recording layer 232. That is, in this example, the magnetic cell size was increased as the magnetic cell layer closer to the substrate side. By increasing the volume of the magnetic cell, the total magnetization of the magnetic cell can be increased. That is, the output signal during reproduction does not deteriorate even when the distance from the head is increased.

FIG. 20 is a schematic cross-sectional view showing an example in which the thickness of the magnetic cell closer to the substrate side is increased. By making the film thickness 140 of the magnetic cell 136 of the first perpendicular magnetic recording layer 231 thicker than the film thickness 141 of the magnetic cell 137 of the second perpendicular magnetic recording layer 232, the magnetic cell of the second perpendicular magnetic recording layer , And the total magnetization of the magnetic cell can be increased. Furthermore, even if the magnetic cell size is the same, the total magnetization amount of the magnetic cell can be increased by increasing the saturation magnetization value as the cell is closer to the substrate side.
The method described above can also be applied to the patterned medium of the first embodiment.

[Example 4]
As shown in FIG. 21, the multilayer magnetic recording medium of Example 4 includes a nonmagnetic substrate 21, an underlayer 22, a first perpendicular magnetic recording layer 231, a second perpendicular magnetic recording layer 232, and a protective film 25. Here, the first perpendicular magnetic recording layer 231 is a granular film, and the second perpendicular magnetic recording layer 232 is a pattern film. The granular recording film is a recording film having a structure in which magnetic crystal grains are surrounded by a nonmagnetic grain boundary region, and the magnetic coupling between the magnetic grains is weakened by the nonmagnetic grain boundaries. The magnetic cells 28 of the second perpendicular magnetic recording layer 232 are separated from each other by the nonmagnetic filling layer 26. The multilayer magnetic recording medium of this embodiment is easier to manufacture than the medium of the above embodiment, but the first perpendicular magnetic recording layer 231 needs to have a sufficiently small particle size. The recording magnetization pattern is as shown in FIG. 22, for example. This is the case where all the magnetizations of the first perpendicular magnetic recording layer 231 are recorded upward and all the magnetizations of the second perpendicular magnetic recording layer 232 are recorded downward.

FIGS. 23A to 23F show a method of manufacturing a composite medium in which the granular recording film and the pattern film of this embodiment are combined. First, as shown in FIG. 23A, for example, a glass substrate having a diameter of 65 mm is used as the nonmagnetic substrate 21. On the glass substrate, 10 nm of MgO is formed as the underlayer 22, and a film obtained by adding Ni to FePt is formed to 4 nm as the first perpendicular magnetic recording layer 231 by sputtering. Here, the Fe element is 50 atomic%, the Pt element is 45 atomic%, and the Ni element is 5 atomic%. Further, C is added in order to make a granular recording film by miniaturizing the magnetic particles and isolating the magnetic particles. In addition to C, O ₂ or SiO ₂ may be added. On top of this, 2 nm of MgO is formed as the nonmagnetic layer 27. In addition, the nonmagnetic layer 27 may be made of Ru, SiO ₂ , Al ₂ O ₃ , Fe ₃ O ₄ , oxide, nitride, or the like. Subsequently, 4 nm of FePt is similarly laminated as the second perpendicular magnetic recording layer 232. Here, in order to make the Curie temperature of the second perpendicular magnetic recording layer 232 lower than the Curie temperature of the first perpendicular magnetic recording layer 231, the Fe element is 45 atomic%, the Pt element is 45 atomic%, and the Ni element is 10 atomic%. Subsequently, a protective layer 29 is formed thereon.

  Next, as shown in FIG. 23B, an imprint resist pattern is formed using an imprint apparatus. The total thickness of the resist 30 is 70 nm, the height of the pattern 301 is 60 nm, and the resist residue 302 is 10 nm. The resist pattern can also be formed by photolithography using an exposure apparatus.

Next, as shown in FIG. 23C, etching is performed in oxygen gas using a reactive ion etching apparatus, and the resist residue 302 and the protective layer 30 in the recesses of the resist pattern are removed. Next, using the resist as a mask, the recording layer is etched using an Ar ion beam. Next, using a reactive ion etching apparatus, etching is performed in hydrogen gas, and the remaining resist 30 and protective layer 29 are removed. Next, as shown in FIG. 23D, NiTi to be the nonmagnetic filling layer 26 is formed. Next, as shown in FIG. 23E, the unevenness of the surface of the nonmagnetic filling layer 26 is reduced to 2 nm or less using an etching apparatus, and the nonmagnetic filling layer 26 is etched with an Ar ion beam using an ion beam etching apparatus. Then, the nonmagnetic filling layer of the recording part is removed. Finally, as shown in FIG. 23F, a protective layer 25 and a lubricating layer (not shown) are formed using a sputtering apparatus.
Recording of magnetization information can be performed by the method shown in the second embodiment.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. In addition, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 11 Magnetic head slider 12 Magnetic head 13 Carriage 14 Voice coil motor 15 Magnetic disk 100 Recording head 101 Upper magnetic pole 102 Lower magnetic pole 103 Main magnetic pole 104 Connection part 105 of upper magnetic pole and lower magnetic pole 105 Conductive pattern 110 Near field light generation part 111 Laser light source 112 Laser beam 113 Optical waveguide 114 Metal scatterer 115 Near-field light 120 Recording medium 130 Playback head 131 Upper shield 132 Lower shield 133 GMR or TMR element 135 Head leading edge 136 Magnetic cell 137 of the first perpendicular magnetic recording layer Second perpendicular Magnetic cell 138 of magnetic recording layer Magnetic cell 139 of third perpendicular magnetic recording layer Head magnetic field 140 Film thickness of first perpendicular magnetic recording layer 141 Film thickness of second perpendicular magnetic recording layer 21 Nonmagnetic substrate 22 Underlayer 23 Perpendicular magnetic recording 231 First perpendicular magnetic recording layer 232 Second perpendicular magnetic recording layer 233 Third perpendicular magnetic recording layer 24 Multilayer recording layer 25 Protective layer 26 Nonmagnetic filling layer 27 Nonmagnetic layer 28 Magnetic cell 29 Protective layer 30 Resist pattern 301 Pattern 302 Residue residue

Claims (12)

A disk-shaped substrate;
A plurality of recording layers formed on the substrate and magnetically separated from each other and stacked,
The recording layer includes a plurality of magnetic cells magnetically separated from each other;
The magnetic cells of each recording layer are regularly arranged in the rotation direction of the substrate in a state where they overlap each other in the direction perpendicular to the film surface,
The magnetic recording medium, wherein a Curie temperature of a magnetic cell included in the plurality of recording layers is higher as a magnetic cell is included in a recording layer closer to the substrate.   2. The magnetic recording medium according to claim 1, wherein the magnetic cell of the recording layer near the substrate has a saturation magnetization value larger than that of the magnetic cell of the recording layer far from the substrate.   3. The magnetic recording medium according to claim 1, wherein the magnetic cell in the recording layer close to the substrate has a larger volume than the magnetic cell in the recording layer far from the substrate. In a thermally assisted magnetic recording apparatus comprising: a magnetic recording medium; a magnetic pole that applies a recording magnetic field to the magnetic recording medium; and a heating unit that heats the magnetic recording medium.
The magnetic recording medium includes a disk-shaped substrate and a plurality of recording layers formed on the substrate and stacked magnetically separated from each other, and the recording layers are magnetically separated from each other A plurality of magnetic cells, and the magnetic cells of each recording layer are regularly arranged in the direction of rotation of the substrate in a state where they overlap each other in the direction perpendicular to the film surface, and the curie of the magnetic cells included in the plurality of recording layers The temperature of the magnetic cell contained in the recording layer close to the substrate is a higher magnetic recording medium,
During recording, a desired magnetic cell to be recorded is near the Curie temperature of the magnetic cell, lower than the Curie temperature of the magnetic cell at a position closer to the substrate than the magnetic cell, and farther from the substrate than the magnetic cell. Heating by the heating means to a temperature higher than the Curie temperature of the magnetic cell at the position, and recording by applying a recording magnetic field from the magnetic pole,
2. A heat-assisted magnetic recording apparatus, wherein recording is performed sequentially in the order of a magnetic cell contained in a recording layer closer to the substrate and a magnetic cell contained in a recording layer farther from the substrate. A disk-shaped substrate;
A plurality of recording layers formed on the substrate and magnetically separated from each other and stacked,
The recording layer includes a plurality of magnetic cells magnetically separated from each other;
2. A magnetic recording medium according to claim 1, wherein magnetic cells of adjacent recording layers are regularly arranged in the direction of rotation of the substrate so as not to overlap each other in the direction perpendicular to the film surface.   6. The magnetic recording medium according to claim 5, wherein the Curie temperature of the magnetic cell located at the same position in the rotational direction and the radial direction of the magnetic recording medium is higher as it is closer to the substrate.   7. The magnetic recording medium according to claim 5, wherein the magnetic layer of the recording layer near the substrate has a saturation magnetization value larger than that of the magnetic cell of the recording layer far from the substrate.   8. The magnetic recording medium according to claim 5, wherein the magnetic cell of the recording layer close to the substrate has a larger volume than the magnetic cell of the recording layer far from the substrate. Magnetic recording medium. In a heat-assisted magnetic recording apparatus comprising: a magnetic recording medium; a magnetic pole that applies a magnetic field to the magnetic recording medium; and a heating unit that heats the magnetic recording medium.
The magnetic recording medium includes a disk-shaped substrate and a plurality of recording layers formed on the substrate and stacked magnetically separated from each other, and the recording layers are magnetically separated from each other A magnetic recording medium including a plurality of magnetic cells, the magnetic cells of adjacent recording layers being regularly arranged in the direction of rotation of the substrate in a state in which they do not overlap with each other in the direction perpendicular to the film surface;
At the time of recording, a desired magnetic cell to be recorded is near the Curie temperature of the magnetic cell and overlaps the magnetic cell in the film thickness direction and is closer to the substrate than the magnetic cell. The magnetic cell is heated by the heating means to a temperature higher than the Curie temperature of the magnetic cell at a position overlapping the magnetic cell in the film thickness direction and far from the substrate than the magnetic cell. Apply and record,
2. A heat-assisted magnetic recording apparatus, wherein recording is performed sequentially in the order of a magnetic cell contained in a recording layer closer to the substrate and a magnetic cell contained in a recording layer farther from the substrate. A disk-shaped substrate;
Two recording layers formed on the substrate and magnetically separated from each other, and
The recording layer far from the substrate includes a plurality of magnetic cells magnetically separated from each other, and the plurality of magnetic cells are regularly arranged in the rotation direction of the substrate,
The magnetic recording medium, wherein the recording layer near the substrate is a granular recording film in which magnetic particles are surrounded by a nonmagnetic grain boundary region.   11. The magnetic recording medium according to claim 10, wherein a Curie temperature of the granular recording film is higher than a Curie temperature of the magnetic cell.   12. The magnetic recording medium according to claim 10, wherein a saturation magnetization value of the granular recording film is larger than a saturation magnetization value of the magnetic cell.

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