JP2008021365A - Information recording medium and manufacturing method thereof, and information recording/reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording medium suitable for high-density magnetic recording, capable of realizing both of high magnetic anisotropy energy and fine crystal particles, and an information recording device to which the information recording medium is mounted. <P>SOLUTION: The information recording medium has, on a nonmagnetic substrate, a soft magnetic base layer formed of a soft magnetic material, a recording layer made of a laminated film in which a layer including Co as a main component and a layer including Pd as a main component are laminated alternately on an amorphous underlayer composed of an alloy layer including Y, Zr, Pd, Ti, Hf, Cr, and Pt, or Y, Zr, Pd, Ti, Hf, Cr, and Pt as main components, and a protective layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an information recording medium used for recording / reproducing information and an information recording / reproducing apparatus including the information recording medium, and more particularly to an information recording medium suitable for high-density recording and an information recording / reproducing apparatus including the information recording medium.

  There is a remarkable development in the information society, and one of the devices that can process not only text information but also voice and image information at high speed is known as a magnetic recording type information recording device mounted on a computer or the like. It has been. At present, development is progressing in the direction of downsizing the information recording apparatus while improving the recording density of the magnetic recording type information recording apparatus. A typical magnetic recording type information recording apparatus has a plurality of information recording media rotatably mounted on a spindle. Each information recording medium includes a substrate and a magnetic film formed thereon, and information recording is performed by forming a magnetic domain having a specific magnetization direction in the magnetic film. Conventionally, the direction of magnetization recorded is in the plane of the magnetic film, which is called the in-plane magnetic recording method. High-density recording of the in-plane magnetic recording type information recording apparatus reduces the thickness of the magnetic film, reduces the size of the magnetic crystal grains, and reduces the magnetic interaction between the grains. Has been achieved.

  However, miniaturization of crystal grains and reduction of the magnetic interaction between the grains are problematic in that the thermal stability of magnetization constituting the recorded bit is lowered. In order to alleviate this problem, a perpendicular magnetic recording method has been proposed, which makes the direction of recorded magnetization perpendicular to the substrate. As a result, the adjacent bits are magnetostatically stable and the recording transition area becomes sharp. Furthermore, by adding a layer made of a soft magnetic material (soft magnetic backing layer) between the recording layer and the substrate, the magnetic field at the time of recording can be sharpened. Recording becomes possible and the thermal stability of magnetization is improved, so that higher density recording is possible.

  A CoPtCr-based alloy (hereinafter referred to as a CoPtCr-based alloy medium) is used for the above-described information recording medium of the in-plane magnetic recording system, and the same CoPtCr-based alloy medium is mainly used as the information recording medium of the perpendicular magnetic recording system. Have been studied. In the case of a CoPtCr-based alloy, the magnetic anisotropy depends on the magnetocrystalline anisotropy due to the Co crystal structure. Pt is added to increase the magnetic anisotropy, and Cr is added to make the crystal grain boundary of the medium nonmagnetic.

  On the other hand, when the magnetic anisotropy increases, the coercive force of the medium increases, and when the coercive force is too high, the magnetic field generated from the recording head cannot sufficiently perform recording. As a method for avoiding this problem, a heat-assisted magnetic recording method has been proposed in which recording is performed by heating and raising the temperature of the medium during recording to reduce the coercive force of the medium.

T.Oikawa et.al, IEEE Trans. Magn., Vol.38, pp.1976-1978, 2002

  However, in order to realize a high recording density, it is necessary to further increase the thermal stability of magnetization, and it is necessary to apply a material having a higher magnetic anisotropy than the CoPtCr-based alloy to the medium. As one of such materials, there is a Co / Pd multilayer film in which layers containing Co as a main component and layers containing Pd as a main component are alternately stacked. This material exhibits high magnetic anisotropy due to the Co / Pd interface. However, the S / N in the magnetic recording medium is not improved because crystal grains are large simply by forming a multilayer film. Therefore, in order to apply this material to a magnetic recording medium so as to obtain good S / N, it is necessary to reduce the crystal grain size.

  The present invention has been made in view of such a situation, and is an information recording medium suitable for high-density magnetic recording, which achieves both high magnetic anisotropy energy and fine crystal grains, and an information recording / reproducing apparatus including the same. Is to provide.

  In order to solve the above-mentioned problems, an information recording medium according to the present invention is a magnetic material in which a recording layer is formed by alternately laminating a layer containing Co as a main component and a layer containing Pd as a main component. An information recording medium of a perpendicular magnetic recording method or a heat-assisted magnetic recording method in which the direction perpendicular to the film surface is larger than the direction, and the underlayer is amorphous Y, Zr, Pd, Ti, Hf, Cr, It contains at least one element selected from Pt and V as a main component. This new information recording medium is excellent in information magnetic characteristics and recording characteristics.

  In order to control the microstructure of the thin film, it is particularly important to control the initial growth of the thin film. A factor that greatly affects the initial growth is the surface energy of the film growth interface. When a thin film is formed with a material having a surface energy higher than that of the underlayer, the growing thin film is grown so as to reduce the surface energy as much as possible, so that it tends to become fine crystal grains, and conversely lower than the underlayer. When forming a thin film with a material having surface energy, the crystal grains tend to be coarse.

  Further, when a material having a lattice constant close to that of the underlayer is grown, the tendency to heteroepitaxially grow on the underlayer is increased, and the crystal grain size is easily affected by the crystal structure of the underlayer. Therefore, in order to control the crystal grain size and crystal plane orientation during thin film formation and growth, the material selection and formation method of the underlayer are very important.

  Therefore, as a result of examining various materials and conditions, we formed the underlayer using a material whose surface energy is lower than that of Co, and controlled the crystallinity of the Co / Pd multilayer film. It was found that it can be miniaturized.

  Specifically, a material containing as a main component at least one element selected from Y, Zr, Pd, Ti, Hf, Cr, Pt, and V, which is an element having a surface energy smaller than that of Co, is used.

  In the present invention, the information recording medium of the present invention is magnetized in the direction perpendicular to the film surface of the recording layer, and is also magnetized in the direction parallel to the film surface of the soft magnetic backing layer. And a perpendicular magnetic recording system comprising: a magnetic head that forms a magnetic circuit in cooperation with a recording layer and a soft magnetic underlayer; and a drive device for driving the magnetic recording medium relative to the head An information recording / reproducing apparatus is provided.

  Further, the magnetic recording medium of the present invention is magnetized in a direction perpendicular to the film surface of the recording layer while heating the medium by a heating mechanism, and parallel to the film surface of the soft magnetic backing layer. And a magnetic head that forms a magnetic circuit in cooperation with the recording layer and the soft magnetic underlayer, and a drive device that drives the magnetic recording medium relative to the head. An assist magnetic recording type information recording / reproducing apparatus is provided.

  In the magnetic recording medium of the present invention, a soft magnetic backing layer may be provided under the underlayer. The role of the soft magnetic backing layer is to focus the magnetic flux leaking from the magnetic head on the recording layer when information is recorded on and reproduced from the recording layer using the magnetic head. As a material for the soft magnetic underlayer, a soft magnetic material having a large saturation magnetization, a small coercive force, and a high magnetic permeability is preferable, and a material corresponding thereto is, for example, a CoTaZr film. The film thickness of the soft magnetic backing layer is preferably in the range of 25 to 500 nm.

  In summary, the information recording medium according to the present invention is an information recording medium used in a perpendicular magnetic recording system in which the residual magnetization is larger in the direction perpendicular to the film surface than in the in-film direction. A recording layer that is formed on the underlayer and is a magnetic material in which layers containing Co as a main component and layers containing Pd as a main component are alternately stacked, and the underlayer has a lower surface energy than Co It is formed of a material containing an element that is not a magnetic material.

  The information recording medium is a method of manufacturing an information recording medium used in a perpendicular magnetic recording method, the step of forming an adhesion layer on a substrate, and the step of forming a soft magnetic backing layer on the adhesion layer. A step of forming an underlayer on the soft magnetic underlayer, a step of forming a recording layer on the underlayer, and a step of forming a protective layer on the recording layer, the recording layer comprising Co It is formed of a magnetic material in which layers containing a main component and layers containing Pd as a main component are alternately stacked, and the underlayer is formed of a material containing an element which is lower in surface energy than Co and is not a magnetic material. It can be manufactured by the manufacturing method of the information recording medium.

  Furthermore, the information recording / reproducing apparatus according to the present invention includes a magnetic head that gives magnetization in the direction perpendicular to the film surface of the recording layer of the information recording medium, and the information recording medium to the magnetic head. And a driving means for relatively driving the motor. This information recording / reproducing apparatus relates to a configuration in the case where heat-assisted recording is not performed.

  An information recording / reproducing apparatus according to the present invention includes a magnetic head provided with a medium heating mechanism that gives magnetization in the direction perpendicular to the film surface while heating the recording layer of the information recording medium to the information recording medium; Drive means for driving the information recording medium relative to the magnetic head. This information recording / reproducing apparatus relates to a configuration in the case of performing heat assist recording.

  Further features of the present invention will become apparent from the best mode for carrying out the present invention and the accompanying drawings.

  According to the magnetic recording medium of the present invention, as a high-density magnetic recording medium, an alloy underlayer mainly composed of Y, Zr, Pd, Ti, Hf, Cr, and Pt, and a magnetic layer in which Co and Pd are alternately stacked are provided. By providing the information recording medium, it is possible to provide an information recording medium capable of high-density recording that achieves both excellent recording characteristics and an information recording / reproducing apparatus including the information recording medium.

  Embodiments of an information recording medium and an information recording apparatus of the present invention will be specifically described below with reference to the accompanying drawings. However, the present invention is not limited to this, and can be modified as appropriate without departing from the essential scope of the present invention.

<First Embodiment>
FIG. 1 is a schematic cross-sectional view of a magnetic disk according to the first embodiment of the present invention. As shown in FIG. 1, the magnetic disk 10 has a structure in which an adhesion layer 2, a soft magnetic backing layer 3, an underlayer 4, a recording layer 5, and a protective layer 6 are sequentially laminated on a substrate 1.

  The adhesion layer 2 is a layer for preventing separation between the substrate 1 and a film laminated thereon, and the soft magnetic backing layer 3 is for focusing a magnetic field applied to the recording layer during information recording. Is a layer. The underlayer 4 is a layer for controlling the fine structure of the recording layer 5. The recording layer 5 is a layer in which information is recorded as magnetization information, and the magnetization direction is perpendicular to the film surface. The protective layer 6 is a layer for protecting the laminated films 2 to 5 sequentially laminated on the substrate 1.

  Hereinafter, a method for producing this magnetic disk will be described. As the substrate 1, a disk-shaped glass substrate having a diameter of 2.5 inches (6.5 cm) is used. On the substrate 1, a Ti film is formed as the adhesion layer 2 by DC sputtering. The sputtering conditions are a gas pressure of 0.28 Pa, an input power of 500 W, and a target of Ti. The film thickness of the adhesion layer 2 is 5 nm. These numerical values are specific examples and are not limited thereto.

Next, a CoTaZr film as a soft magnetic backing layer 3 was formed on the adhesion layer 2 by DC sputtering. The sputtering conditions are a gas pressure of 0.28 Pa, an input power of 400 W, and the target composition is Co ₈₈ Ta ₁₀ Zr ₂ (at%). The thickness of the soft magnetic backing layer 3 is 100 nm. From the viewpoint of mass productivity, it is preferable to make the thickness of the soft magnetic backing layer 3 as thin as possible. However, if it is too thin, it is difficult to pass magnetic flux. Therefore, the thickness is preferably in the range of 50 nm to 150 nm, and in the present embodiment, the thickness is set to 100 nm.

  Next, a PdSi alloy film is formed as a base layer 4 on the soft magnetic backing layer 3 by a DC magnetron sputtering method. The PdSi alloy simultaneously discharges the Pd target and the Si target, and adjusts the power applied to each target to adjust the PdSi alloy composition. Here, the thickness of the underlayer is 10 nm. The distance from the magnetic head to the soft magnetic layer should be as short as possible. However, if the film thickness is too thin, the above-described structure control will not work well. Therefore, in general, the thickness of the underlayer is preferably 5 nm to 15 nm, and needs to be at least 20 nm or less.

  In this embodiment, a material containing Pd (palladium) is used for the underlayer, but other materials such as Y (yttrium), Zr (zirconium), Ti (titanium), Hf (hafnium), Cr (chromium), Even when an alloy containing Pt (platinum) and V (vanadium) is used, the same effect as that obtained when Pd is used can be obtained.

  Next, a Co / Pd multilayer magnetic film is formed as the recording layer 5 on the underlayer 4. The multilayer film uses Ar gas to discharge Pd targets and Co targets by DC magnetron sputtering, and opens and closes a shutter on each target, so that 0.2 nm thick Co and 0.7 nm thick Pd are formed. It forms by the method of laminating | stacking on the base layer 4 by turns. The number of stacked layers is 20 layers, and the sputtering conditions are a gas pressure of 0.8 Pa, a Co target, and a Pd target with an input power of 100 W. One layer of the multilayer film is preferably less than 1 nm in total, and as described above, Co film thickness: Pd film thickness = 2: 7, or 3: 7. Under this condition, high perpendicular magnetic anisotropy is exhibited.

  Finally, an amorphous carbon film is formed as a protective layer 6 on the recording layer 5 by DC sputtering. The sputtering conditions are a gas pressure of 0.20 Pa, an input power of 300 W, and the thickness of the protective layer 6 is 3 nm.

(Comparative Example 1)
In Comparative Example 1, a Pd layer was used as the base layer 4. Other than that, it produces similarly to 1st Embodiment. The first embodiment and Comparative Example 1 are evaluated by X-ray diffraction in order to measure crystallinity. The evaluation result is as shown in FIG. In FIG. 2, the horizontal axis represents 2θ (diffraction angle) and the vertical axis represents the intensity of X-rays.

  In both the first embodiment and the first comparative example, a peak (corresponding to the surface spacing of each layer) due to (111) of the Co / Pd multilayer film is observed around 41 °. According to this, it can be seen that changing the underlayer does not affect the peak of the CoPd layer.

  On the other hand, in the case of Comparative Example 1, the peak of the underlayer Pd is observed at 40.2 °, whereas the peak intensity due to the underlayer of the first embodiment decreases with the Si addition amount, and at 13 at%. Almost no peaks are observed. That is, it can be seen that the crystal lattice of the underlayer is broken in the first embodiment.

  In order to investigate this change, the cross section and the plane transmission atomic microscope (TEM) observation of the sample with the Si addition amount of 13 at% of the first embodiment and the sample of Comparative Example 1 were performed. The result is shown in FIG. FIG. 3A shows a cross-sectional TEM image of the sample, and FIG. 3B shows a planar TEM image of the sample.

  From the cross-sectional TEM image of FIG. 3A, it can be seen that the sample of Comparative Example 1 is a crystalline underlayer, whereas the sample with a Si addition amount of 13 at% is amorphous. 3A shows that the crystal lattice is clearly observed in Comparative Example 1, whereas the crystal is unclear and non-crystallized in this embodiment. I understand. 3B also shows that the crystal grain size of the Co / Pd multilayer film of the first embodiment is miniaturized with the addition of Si.

FIG. 4 shows the relationship between the Si addition amount and the crystal grain size. With the addition amount of Si, the crystal grain size is reduced to almost half from 12 nm to 6 nm.
Table 1 shows the crystal grain sizes of Example 1 and Comparative Example 1 obtained from planar TEM image analysis.

  From the above experimental results, it can be seen that even when the same material is used, the crystal grain size of the Co / Pd multilayer film changes as the crystallinity changes. It is thought that the change in the crystallinity of the underlayer affected, and as the crystallinity deteriorates, the influence of the crystal orientation plane of the underlayer is reduced, and the surface energy inherent to the material of the underlayer is reduced in the Co / Pd multilayer film. It is thought that it had a strong influence.

(Comparative Example 2)
In Comparative Example 2, a Ta ₈₇ Si ₁₃ (at%) layer is used as the underlayer 3. The rest is the same as in the first embodiment.
X-ray diffraction of the sample of Comparative Example 2 was measured, and it was confirmed that the underlayer was amorphous. Table 2 shows the crystal grain size obtained from the planar TEM image of Comparative Example 2.

  The crystal grain size of Comparative Example 2 is larger than that of Comparative Example 1 despite the addition of Si. This is because the surface energy of Ta, which is the main component of the underlayer, is larger than Co and Pd. In other words, it is considered that Co and Pd formed on the underlayer are easily grown in layers in order to reduce the surface energy.

  Next, the evaluation of the recording / reproduction characteristics of the first embodiment, Comparative Example 1 and Comparative Example 2 will be described. When evaluating the recording / reproducing characteristics, a soft magnetic backing layer CoTaZr is formed to a thickness of 100 nm below the underlayer. Since the soft magnetic underlayer has an effect of increasing the recording magnetic field, the recording characteristics can be improved.

  After applying a 1 nm thick lubricant on the protective layer of the information recording medium according to the first embodiment and the comparative example 1, the information recording medium is mounted in the information recording / reproducing apparatus 50 shown in FIG. To evaluate the recording and playback characteristics.

  In the information recording / reproducing apparatus 50 in FIG. 5, a recording or reproduction control signal is input to a recording / reproduction control circuit 53 from a host apparatus (not shown) via a recording / reproduction control terminal. Further, the recording / reproducing circuit 54 outputs the reproduction data to the host device via the recording / playback data terminal or receives the recording data from the host device.

  Then, the recording / reproducing control circuit 53 instructs the semiconductor laser driving circuit 55 to output a laser driving current corresponding to the recording or reproducing by the recording / reproducing control signal. The recording / reproducing control circuit 53 instructs the recording / reproducing circuit 54 to process the recording data or the reproducing data, and processes the recording signal or the reproducing signal to the magnetic head driving circuit 52 which is the recording unit and the reproducing unit. Instruct them to do so.

  The semiconductor laser drive circuit 55 drives the semiconductor laser 56 with a drive current corresponding to recording or reproduction. The semiconductor laser 56 emits a laser beam having an intensity corresponding to the magnitude of the drive current from the semiconductor laser drive circuit 55 and irradiates the micro optical head 57.

  FIG. 6 is a cross-sectional view showing a schematic configuration of the recording / reproducing head 60. The recording / reproducing head 60 includes a magnetic head 51 (recording magnetic head 61 and reproducing magnetic head 62) and a micro optical head 57 that constitutes a light irradiation unit used during heat assist.

  In FIG. 6, the magnetic head 51 incorporates a light irradiator (micro optical head 57) in which an optical laser that generates a laser having a wavelength of 405 nm and an opening are integrated, and when performing information recording by heat-assisted recording. Can heat the medium 10. For example, a thin film magnetic head can be used as the recording magnetic head, and a spin valve magnetic head can be used as the reproducing magnetic head, and these and the light irradiation unit are integrated.

  As shown in FIG. 6, the head structure includes a recording magnetic head 61 (with trailing shield, trailing shield gap length Gts = 35 nm, Tw = 70-100 nm, magnetic flux density 2.45 T), reproducing magnetic head. 62 (Twr = 60 nm, Gs = 50 nm, MR ratio = 13%) is used. The reproducing magnetic head 62 can detect the magnetic flux leaking from the bit immediately below the reproducing head by the magnetic shield 63. The integrated magnetic head 60 is controlled by a magnetic head drive circuit 52, and the distance between the magnetic head surface of the information recording / reproducing apparatus 50 and the information recording medium surface is kept at 5 nm. The magnetic head driving device 52 drives the information recording medium 10 relative to the magnetic head 51.

  Magnetization in a direction perpendicular to the film surface of the recording layer 4 of the information recording medium 10 is given by the magnetic head 51 of the information recording / reproducing apparatus 50, and magnetization in a direction parallel to the film surface of the soft magnetic backing layer 6. And a magnetic circuit can be constructed in cooperation with the recording layer and the soft magnetic backing layer 6.

  This information recording medium 10 is used as a reproduction output (Slf) when a signal having a linear recording density of 20 kFCI is recorded, and a ratio with a noise (Nd) at a linear recording density of 1000 kFCI is a recording / reproduction characteristic (Slf) of the information recording medium. / Nd ratio). Recording was performed while heating the recording medium by applying a power of 10 mW to the optical laser. Table 3 shows the measurement results of the Slf / Nd ratio.

<Second Embodiment>
In the second embodiment, the recording / reproduction evaluation is performed with the same film structure as in the first embodiment. At that time, unlike the first embodiment, thermal assist during recording is not performed (that is, the laser irradiation from the minute optical head 57 in FIG. 5 is turned off), and normal perpendicular magnetic recording is performed at room temperature. Do it by recording. Similarly to the first embodiment, the reproduction output (Slf) when a signal with a linear recording density of 20 kFCI is recorded, and the ratio with the noise (Nd) at a linear recording density of 1000 kFCI is the recording / reproduction characteristic of the information recording medium. Evaluation is made as (Slf / Nd ratio). Table 4 shows the measurement results of the Slf / Nd ratio. For comparison, Table 4 also shows the recording / reproducing characteristics when perpendicular magnetic recording is performed on the medium of Comparative Example 1.

  Thus, it can be seen that, even in the conventional perpendicular magnetic recording system, the second embodiment exhibits better recording and reproduction characteristics than Comparative Example 1 and Comparative Example 2.

<Third Embodiment>
In the third embodiment, the underlayer 4 is formed using various alloy materials having a surface energy lower than that of Co, and the same film structure as that of the first embodiment is employed.

  Table 5 shows the material of the underlayer of the produced magnetic recording medium, the magnetic characteristics, and the reproduction output (Slf) when recording a signal with a linear recording density of 20 kFCI, and the ratio with the noise (Nd) at a linear recording density of 1000 kFCI. The recording / reproduction characteristic (Slf / Nd ratio) result of the information recording medium is shown. During recording, both the thermally assisted magnetic recording method in which the medium is heated with an optical laser and the perpendicular magnetic recording method without using the optical laser are evaluated.

  Note that the thickness of the underlayer is desirably 20 nm or less. This is because the closer the spacing between the recording head and the soft magnetic underlayer, the better the recording characteristics.

  In each of the above-described embodiments, the example in which glass is used as the substrate material of the information recording medium has been described, but the present invention is not limited to this. In some cases, a plastic such as aluminum or polycarbonate, or a resin may be used.

  Moreover, although each embodiment demonstrated using the example which provided the CoTaZr film | membrane as a soft magnetic backing layer of an information recording medium, this invention is not limited to this. The soft magnetic backing layer may be FeTaC, FeTaN, FeAlSi, FeC, CoB, CoTaNb, NiFe, or a laminated film of these soft magnetic films and C films. However, the CoTaZr film is most desirable.

  Furthermore, in each embodiment, Si is used as an element for deconsolidating the underlayer, but the present invention is not limited to this, and C (carbon) or B (boron: boron) can also be used.

  As described above, according to the magnetic recording medium according to the embodiment of the present invention, the recording is a magnetic material that is formed on the underlayer and alternately stacks the layer mainly composed of Co and the layer mainly composed of Pd. Since the underlayer has a surface energy lower than that of Co and is formed of a material containing an element that is not a magnetic material, an information recording medium having recording / reproducing characteristics and an information recording / reproducing apparatus including the same are provided. can do.

  Here, for example, a recording layer is formed on an underlayer composed of Y, Zr, Pd, Ti, Hf, Cr, Pt or an alloy layer mainly composed of Y, Zr, Pd, Ti, Hf, Cr, Pt. The information recording medium is specifically realized by adopting a structure that forms a magnetic recording layer in which layers containing Co as a main component and layers containing Pd as a main component are alternately laminated.

It is a figure which shows the cross-section of the information recording medium by 1st Embodiment. It is a graph which shows the X-ray-diffraction measurement result of 1st Embodiment and the comparative example 1. FIG. It is a figure which shows the transmission electron microscope image of 1st Embodiment and the comparative example 1. FIG. It is a figure shown about the relationship between Si addition amount of 1st Embodiment and Comparative Example 1 and a crystal grain diameter. It is the schematic of the information recording device provided with the information recording medium by this invention. It is a schematic sectional drawing of a magnetic head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Adhesion layer 3 Soft magnetic backing layer 4 Underlayer 5 Recording layer 6 Protective layer 10 Information recording medium 50 Information recording / reproducing apparatus 51 Magnetic head 52 Magnetic head drive system

Claims (10)

An information recording medium used in a perpendicular magnetic recording system in which the remanent magnetization is larger in the direction perpendicular to the film surface than in the film surface direction,
An underlayer,
A recording layer that is a magnetic material formed on the underlayer and alternately stacks a layer containing Co as a main component and a layer containing Pd as a main component;
The information recording medium according to claim 1, wherein the underlayer is made of a material having a surface energy lower than that of Co and containing an element that is not a magnetic material.   2. The information recording medium according to claim 1, wherein the underlayer is formed of a material containing at least one element of Y, Zr, Pd, Ti, Hf, Cr, Pt, and V as a main component. .   3. The information recording medium according to claim 1, wherein the material forming the underlayer further contains an element that makes the crystal structure of the underlayer amorphous.   The information recording medium according to any one of claims 1 to 3, wherein the underlayer has a thickness of 20 nm or less. A method of manufacturing an information recording medium used in a perpendicular magnetic recording method,
Forming an adhesion layer on the substrate;
Forming a soft magnetic backing layer on the adhesion layer;
Forming an underlayer on the soft magnetic underlayer;
Forming a recording layer on the underlayer;
Forming a protective layer on the recording layer,
The recording layer is formed of a magnetic material in which a layer containing Co as a main component and a layer containing Pd as a main component are alternately stacked. The underlayer has a surface energy lower than that of Co and contains an element that is not a magnetic material. A method for producing an information recording medium, characterized in that the information recording medium is formed.   6. The information recording medium according to claim 5, wherein the underlayer is formed of a material containing at least one element of Y, Zr, Pd, Ti, Hf, Cr, Pt, and V as a main component. Manufacturing method.   7. The method of manufacturing an information recording medium according to claim 5, wherein the material forming the underlayer further includes an element that makes the crystal structure of the underlayer amorphous.   The film thickness of the soft magnetic underlayer is 150 nm or less, the film thickness of the underlayer is 20 nm or less, and the film thickness of the recording layer is 20 nm or less. 2. A method for producing an information recording medium according to item 1. A magnetic head that gives magnetization in the direction perpendicular to the film surface of the recording layer of the information recording medium to the information recording medium according to any one of claims 1 to 4,
An information recording / reproducing apparatus comprising: drive means for driving the information recording medium relative to the magnetic head. 5. A magnetic head comprising a medium heating mechanism that applies magnetization to the information recording medium according to claim 1 in a direction perpendicular to the film surface while heating the recording layer of the information recording medium; ,
Driving means for driving the information recording medium relative to the magnetic head;
An information recording / reproducing apparatus comprising:

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