JP2010287290A - Perpendicular magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a perpendicular magnetic recording medium which enable high density recording. <P>SOLUTION: The perpendicular magnetic recording medium includes a first intermediate layer 106, a second intermediate layer 107, and magnetic recording layers 108 and 109 on a substrate 100. The first intermediate layer includes Ru or an Ru alloy. The second intermediate layer contains at least one element selected from Co and Fe, contains Cu as a principal component is constituted of an alloy whose total rate of Co and Fe is 10 to 30 at.%, and has a film thickness between 5 nm and 100 nm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic recording medium, and more particularly to a perpendicular magnetic recording medium that realizes high-density magnetic recording.

  A perpendicular magnetic recording medium mounted on a commercially available hard disk drive has a structure in which a soft magnetic backing layer, a seed layer, an intermediate layer, a magnetic recording layer, and a protective layer are laminated in this order on a substrate.

  A perpendicular magnetic recording medium having excellent characteristics is expected to have uniform crystal orientation and grain shape of crystal grains contained in the magnetic recording layer. Further, the recording characteristics can be improved by a structure that increases the gradient of the magnetic field generated from the recording head.

  In order to realize high-density recording such as 960 megabits / square millimeter (620 gigabits / square inch), in addition to improving the uniformity of crystal grains contained in the magnetic recording layer and the magnetic field gradient of the recording head, the recording layer of the medium Must be reduced to 10 nm or less, or the protective film can be thinned to reduce the distance between the recording / reproducing head and the magnetic recording layer so that recording / reproduction can be performed with high resolution.

  On the other hand, if the particle diameter constituting the recording layer of the medium is reduced to 10 nm or less, the thermal stability of the recorded signal becomes a problem. If the particle diameter is simply reduced, the magnetic anisotropy energy that fixes the magnetization direction of the recording layer particles decreases. When the magnetic anisotropy energy decreases, the magnetization of the recording layer is easily disturbed by the influence of thermal energy. As a result, the recorded signal is attenuated and the signal quality is lowered, and in some cases, the reliability of the reproduced signal is lowered. For this reason, it is necessary to reduce the particle size and improve the thermal stability of the recorded signal. As a solution to this problem, it is conceivable to use a highly magnetic anisotropic material. However, it is difficult to significantly increase the magnetic anisotropy in a magnetic recording medium using a Co—Cr—Pt alloy system as a recording layer. Even when the magnetic anisotropy of the medium can be greatly improved, it is necessary to greatly increase the head magnetic field strength in order to ensure the same recording characteristics as before. However, it is not easy to significantly increase the head magnetic field strength. Further, when the protective film is thinned, it becomes a problem that it is corroded by moisture or oxygen contained in the atmosphere, and it is necessary to ensure sufficient corrosion resistance.

  Against this background, as a medium using a perpendicular magnetic recording method that has been put into practical use in recent years, a magnetic flux slit layer is provided between a seed layer and a nonmagnetic intermediate layer, as described in Patent Document 1, for example. Therefore, the strength and gradient of the head magnetic field are increased to improve the quality of the recording signal.

JP 2006-190486 A

In Patent Document 1, although the magnetic field gradient is improved, the thermal stability and reliability of the medium recording layer are not considered. In order to realize high-density recording such as 960 megabits / square millimeter (620 gigabits / square inch), the following three conditions must be satisfied.
(1) The thermal stability is improved without significantly increasing the magnetic anisotropy of the medium recording layer.
(2) Ensuring sufficient corrosion resistance reliability even if the protective film is thin.
(3) The signal-to-noise ratio is 12.0 dB or more while ensuring thermal stability and corrosion resistance.

The perpendicular magnetic recording medium of the present invention includes an intermediate layer under the magnetic recording layer.
The intermediate layer contains Cu as a main component and contains at least one element selected from Co and Fe, and the total ratio of Co and Fe can be 10 to 30 at.% And the film thickness can be 5 to 100 nm.

  The intermediate layer also has a structure in which a first intermediate layer and a second intermediate layer are sequentially laminated, and the first intermediate layer on the substrate side is made of Ru or a Ru alloy, and the second intermediate layer thereon is made of Cu. You may comprise with the alloy which contains at least 1 element chosen from Co and Fe as a main component, and the total ratio of Co and Fe becomes 10-30 at.%. At this time, the film thickness of the second intermediate layer is set to 5 nm to 100 nm.

  The intermediate layer may have a structure in which a first intermediate layer, a second intermediate layer, a third intermediate layer, and a fourth intermediate layer are sequentially stacked as viewed from the substrate side. In that case, the first intermediate layer and the third intermediate layer are made of Ru or a Ru alloy, and the second intermediate layer and the fourth intermediate layer contain Cu as a main component and contain at least one element selected from Co and Fe. And an alloy in which the total proportion of Fe is 10 to 60 at.%. The total film thickness of the second intermediate layer and the fourth intermediate layer is 15 nm or more and 100 nm or less.

  The intermediate layer may have a laminated structure composed of an even number of 6 to 12 layers. In that case, the odd-numbered intermediate layer as viewed from the substrate side is made of Ru or a Ru alloy, and the even-numbered intermediate layer contains Cu as a main component and contains at least one element selected from Co and Fe. It is made of an alloy having a total ratio of 10 to 60 at.%. The total thickness of the even-numbered intermediate layers is 15 nm or more and 100 nm or less.

  The intermediate layer may have a structure in which a first intermediate layer, a second intermediate layer, and a third intermediate layer are sequentially stacked as viewed from the substrate side. In that case, the first intermediate layer and the third intermediate layer are made of Ru or a Ru alloy, and the second intermediate layer contains Cu as a main component and contains at least one element selected from Co and Fe, and the total ratio of Co and Fe Is made of an alloy having a content of 10 to 30 at. The film thickness of the second intermediate layer is 5 to 100 nm, and the film thickness of the third intermediate layer is 20 nm or less.

  According to the present invention, it is possible to reduce a change with time due to thermal fluctuation, at the same time to satisfy corrosion resistance reliability, and to make a signal-to-noise ratio 12.0 dB or more.

1 is a diagram showing a cross-sectional configuration example of a perpendicular magnetic recording medium according to the present invention. FIG. 3 is a diagram showing a cross-sectional configuration of a perpendicular magnetic recording medium of Comparative Example 1. FIG. 5 is a diagram showing the characteristics of the backing layer and the characteristics of the perpendicular magnetic recording medium with the film thickness changed in Experimental Example 1. The figure which shows the characteristic of the perpendicular magnetic recording medium of Experimental example 1 and Comparative example 1. FIG. The figure which shows the characteristic of the perpendicular magnetic recording medium of Experimental example 2 and Comparative example 1. FIG. The figure which shows the characteristic of the perpendicular magnetic recording medium of Experimental example 3 and Comparative example 1. FIG. The figure which shows the signal noise ratio and signal attenuation factor of Experimental example 4. The figure which shows the cross-sectional structural example of the other perpendicular magnetic recording medium by this invention. FIG. 10 is a diagram illustrating characteristics of the perpendicular magnetic recording medium of Experimental Example 5. The figure which shows the cross-sectional structural example of the other perpendicular magnetic recording medium by this invention. The figure which shows the cross-sectional structural example of the other perpendicular magnetic recording medium by this invention. FIG. 10 is a diagram showing characteristics of the perpendicular magnetic recording medium of Experimental Example 7. The figure which shows the cross-sectional structural example of the other perpendicular magnetic recording medium by this invention. The figure which shows the cross-sectional structural example of the other perpendicular magnetic recording medium by this invention. The figure which shows the cross-sectional structural example of the other perpendicular magnetic recording medium by this invention. FIG. 10 is a diagram showing characteristics of the perpendicular magnetic recording medium of Experimental Example 11.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Experimental Example 1]
FIG. 1 shows a cross-sectional configuration of a vertical axis recording medium of Experimental Example 1 of the present invention.
This magnetic recording medium includes an adhesion layer 101, a soft magnetic backing layer 102, a nonmagnetic coupling layer 103, a soft magnetic backing layer 104, a seed layer 105, a nonmagnetic intermediate layer 106, a ferromagnetic intermediate layer 107, a recording on a substrate 100. The layer (108, 109) and the protective layer 110 are stacked. A lubricating film may be formed on the protective film 110. Further, a similar magnetic recording medium may be configured on both surfaces of the substrate 100.

  As a manufacturing method of the 101 to 110 layers, a DC magnetron sputtering method, an RF magnetron sputtering method, a pulse sputtering method, a counter target sputtering method, or the like can be used. Hereinafter, an experimental example using the DC magnetron sputtering method in a sputtering apparatus capable of continuously forming a multilayer film will be described in detail.

  As the substrate 100, for example, a chemically strengthened glass substrate, a rigid substrate obtained by plating a nickel alloy containing phosphorus on an aluminum alloy, a Si substrate, or the like can be used. Here, a chemically strengthened glass substrate having an outer diameter of 65 mm, an inner diameter of 20 mm, and a thickness of 0.8 mm was used after being washed with water and dried.

  As the adhesion layer 101, a NiTa layer having a thickness of 10 nm was formed. As the characteristics of the adhesion layer 101, a material having high adhesion to the substrate and the upper layer of the adhesion layer is good, and a paramagnetic Ni-based alloy, Co-based alloy, Al-based alloy or the like can be used. For example, there are AlTi alloy, NiAl alloy, CoTi alloy, AlTa alloy and the like.

  A soft magnetic backing layer having a three-layer structure in which the first soft magnetic backing layer 102 and the second soft magnetic backing layer 104 are laminated via a thin nonmagnetic coupling layer 103 was used. Here, 92 at.% Co-3 at.% Ta-5 at.% Zr was used as the first and second soft magnetic backing layers, and an Ru layer was used as the nonmagnetic coupling layer 103. With such a three-layer configuration, the upper and lower CoTaZr alloy layers are antiferromagnetically coupled via the Ru layer, and noise caused by the soft magnetic underlayer can be reduced. In this experimental example, the thickness of this Ru layer was set to 0.7 nm so that the antiferromagnetic coupling between the first and second soft magnetic backing layers was maintained. Further, an additive element may be added to Ru as long as the flatness of the film is maintained.

  The film thicknesses of the first and second soft magnetic underlayers may be adjusted according to the characteristics of the recording head and the recording layer. A sample laminated up to the soft magnetic underlayer was also prepared, and the saturation magnetic flux density evaluated by applying a maximum magnetic field of 1035 kA / m in the in-plane direction using a vibration type magnetometer was 1.25T. Even when the nonmagnetic coupling layer 103 was not provided, the saturation magnetic flux density was 1.23 T. Instead of the 92at.% Co-3at.% Ta-5at.% Zr alloy containing Co as the main component, Fe such as 51at.% Fe-34at.% Co-10at.% Ta-5at.% Zr alloy is mainly used. An alloy as a component can also be used.

  The nonmagnetic coupling layer 103 formed between the first soft magnetic backing layer and the second soft magnetic backing layer functions to antiferromagnetically couple the first soft magnetic backing layer and the second soft magnetic backing layer. As the material used for the nonmagnetic layer, Ru and Cu are used in the case where an amorphous alloy containing Co as a main component is used for both soft magnetic layers, and an amorphous alloy containing Fe as a main component is used for both soft magnetic layers. When used, it is desirable to use Cr or Ru. For example, it is possible to use an alloy containing Ru or an alloy containing Ru as a main component, such as a RuFe alloy. In order to increase the antiferromagnetic coupling magnetic field, the thickness of the nonmagnetic layer 103 is approximately 0.5 nm to 0 nm when using an alloy containing Ru or an alloy containing Ru as a main component. .8 nm should be set.

  For the first soft magnetic underlayer and the second soft magnetic underlayer, an alloy that has high magnetic permeability such as a Co—Ta—Zr alloy magnetic layer, an Fe—Co—Ta—Zr alloy magnetic layer, and provides corrosion resistance reliability is used. It is desirable to use it. It is preferable that the products of the residual magnetic flux density and the film thickness of each soft magnetic layer are substantially equal and have a size capable of antiferromagnetic coupling through the nonmagnetic layer 103. In order to suppress the noise caused by the residual magnetization of the soft magnetic underlayer after the soft magnetic underlayer is antiferromagnetically coupled and the magnetization state of the upper recording layer is determined, the first soft magnetic underlayer 102 has a thickness of 30 nm. A 51 at.% Fe-34 at.% Co-10 at.% Ta-5 at.% Zr alloy film is formed, a 0.7 nm thick Ru film is formed as the nonmagnetic layer 103, and then the second soft magnetic backing layer is formed again. It is also possible to form a 51 at.% Fe-34 at.% Co-10 at.% Ta-5 at.% Zr alloy film having a thickness of 30 nm as 104.

  The seed layer 105 has a structure in which Ni-37.5 at. Ta with a thickness of 2 nm and Ni-10 at.% Cr-3 at.% W with a thickness of 9 nm are sequentially formed. The seed layer 105 plays a role of controlling the crystal orientation and crystal grain size of the nonmagnetic intermediate layer 106. The film thickness, configuration, and material of the seed layer 105 may be set within a range in which the above effects can be obtained, and are not particularly limited to the above film thickness, configuration, and material.

  In the configuration of the seed layer 105, the role of the NiTa layer is to control the orientation of the NiCrW layer and to increase the (111) orientation of NiCrW. The film thickness may be set within a range where this is satisfied, and a value of about 1 nm to 5 nm is usually used. Instead of the NiTa alloy, an amorphous material such as an AlTi alloy, CrTi alloy or CrTa alloy, or a microcrystalline material such as Ta may be used. The role of the NiCrW layer is to increase the c-axis orientation in the direction perpendicular to the film surface of the nonmagnetic intermediate layer (Ru) thereon and to control the grain size and unevenness. The film thickness may be set within a range where this is satisfied, and a value of about 2 nm to 12 nm is usually used. Instead of the NiCrW alloy, Pd, Pt, Cu, Ni having a face-centered cubic lattice (fcc) structure or an alloy containing these can also be used. In particular, an alloy containing at least one element selected from at least W, Cr, and Cu mainly composed of Ni is preferable because segregation of the recording layer can be promoted.

  As the nonmagnetic intermediate layer 106, a Ru layer having a thickness of 28 nm was formed. The role of the nonmagnetic intermediate layer 106 is to control the crystal grain size and crystal orientation of the recording layer and to reduce exchange coupling between crystal grains. What is necessary is just to satisfy this characteristic. In addition to Ru, Ru, Ti, V, Co, Cr, Cu, Nb, Mo, Rh, Ta, W, Re, Ir, Pt, C, Si, Zr, Hf, Al, An alloy with B, C or the like may be used.

  Here, the nonmagnetic intermediate layer 106 is formed in two layers. First, the lower half was formed at a gas pressure of 1 Pa and a film formation rate of 4 nm / s, and later the upper half was formed at a gas pressure of 6.5 Pa and a film formation rate of 1.5 nm / s. By forming the lower layer Ru at a low gas pressure and a high rate and forming the upper layer Ru at a high gas pressure and a low rate, it is possible to suppress the deterioration of orientation and promote segregation of the recording layer.

  The role of the ferromagnetic intermediate layer 107 is to control the crystal grain size and crystal orientation of the recording layer similar to the nonmagnetic intermediate layer 106 and to reduce exchange coupling between crystal grains, as well as the upper recording layer (108, 109). Is to absorb the magnetic flux that comes from. In this experimental example, a Cu-14 at.% Co-6 at.% Fe layer was formed as the ferromagnetic intermediate layer 107 in a range of 1.5 to 200 nm at a gas pressure of 6.5 Pa and a film formation rate of 1.5 nm / s. . Since the atomic arrangement of the (111) plane of Cu having a face-centered cubic (fcc) structure is the same as the (00.1) plane of Ru having a hexagonal close-packed (hcp) structure, the crystal orientation of the lower Ru layer is Cu can be laminated while maintaining and improving. Further, most of Co and Fe precipitated without being dissolved in the Cu matrix, thereby forming CoFe fine particles. A sample in which the soft magnetic backing layer was omitted and the ferromagnetic intermediate layer was laminated was prepared, and the magnetic properties of only the ferromagnetic intermediate layer 107 were evaluated by a vibration type magnetometer. When the magnetic field was applied to 2.4 MA / m, the sample was ferromagnetic. The magnetic flux density of the intermediate layer 107 was 0.43T.

  The first recording layer 108 is a layer containing Co as a main component, Cr and Pt, and further an oxide, and a plurality of layers may be laminated. For the formation, a composite target containing a CoCrPt alloy and SiOx was used. When forming the first recording layer 108, a mixed gas of argon and oxygen was used as the sputtering gas, and the total gas pressure was 5 Pa and the oxygen concentration was 1.67%. The film thickness of the first recording layer 108 was 14 nm, and the film was formed at a film forming rate of 3 nm / s under the condition of a substrate bias of −200V. The composition ratio (at.%) Of the first recording layer was (Co + Cr + Pt) :( Si + O) = 83.4: 16.6, Co: Cr: Pt = 60.6: 14.1: 25.3, O : Si = 3.2: 1.

  The second recording layer 109 is a layer containing Co as a main component and containing Cr and no oxide, and may have a structure in which a plurality of layers are stacked. When forming the second recording layer 109, a CoCrPt alloy target was used, argon was used as the sputtering gas, the gas pressure was 1 Pa, and the film formation rate was 2 nm / s. The film thickness of the second recording layer 109 was 9 nm and 70 at.% Co-16 at.% Cr-14 at.% Pt.

  As the protective layer 110, a diamond-like carbon film having a thickness of 3 nm was formed. The surface was coated with perfluoropolyether, which is an organic lubricant, to form a lubricating layer.

[Comparative Example 1]
As Comparative Example 1, a medium having a cross-sectional configuration shown in FIG. Comparative Example 1 has the same layer configuration as the medium of Experimental Example 1 except that the ferromagnetic intermediate layer 107 is not provided in Experimental Example 1.

The media of Experimental Example 1 and Comparative Example 1 were evaluated by the following method.
In the evaluation of thermal fluctuation resistance, a signal having a recording density of 9.2 megabit / meter was recorded on a medium at an environmental temperature of 80 ° C., and then a change in reproduction signal amplitude with time was measured. From the result, the signal attenuation rate, which is the ratio between the signal output immediately after recording and the signal output after 10,000 seconds from recording, was obtained. The smaller the signal attenuation rate, the better. The product needs to be 25% or less for commercialization.

For the recording / reproduction evaluation, a wrap around shield type recording head having a main magnetic pole width of 50 nm and a reproducing head having a geometric element width of 30 nm were used. The signal-to-noise ratio was obtained from the ratio of the 0-p output of the signal and the noise output in the reproduced waveform immediately after recording a signal with a linear recording density of 38 kbits / mm. In order to achieve 960 Mbit / mm ² , the signal to noise ratio needs to be 12.0 dB or more.

  Corrosion resistance was evaluated by the following method. A perpendicular magnetic recording medium formed on a glass substrate having an outer diameter of 65 mφ is left in a temperature / humidity environment tank at a temperature of 60 ° C. and a relative humidity of 95% for 4 days. The disk was taken out, and the corrosion point on the surface of the magnetic disk was counted by the Corrosion Analysis measurement of Optical Surface Analyzer Model 2120 manufactured by Candela Instruments. It has been empirically found that if the corrosion score in this test is approximately 75 or less, sufficient corrosion resistance can be obtained as a magnetic disk used for a hard disk drive.

The results of these comparative experiments are shown in FIG.
From this result, in Comparative Example 1, the signal-to-noise ratio exceeds 12.0 dB and the number of corrosion points is 64 and the standard 75 or less, but the signal attenuation rate is 32% and the standard 25% or less. Not.

  On the other hand, in Experimental Example 1, the signal attenuation rate is improved as the CuCoFe alloy film, which is a ferromagnetic intermediate layer, becomes thicker. I was able to. Further, the signal-to-noise ratio exceeded the reference value of 12.0 dB when the CuCoFe film thickness was 3 nm or more and 100 nm or less.

  From these results, it became clear that the object of the present invention can be achieved by setting the film thickness of the ferromagnetic intermediate film 107 to 5 to 100 nm in the medium having the film configuration shown in FIG.

  Further, a magnetic recording medium was manufactured in the same manner as in Experimental Example 1 except that the nonmagnetic coupling layer 103 was not provided. As a result, no spike noise was observed, and the film thickness dependence of the error rate characteristics similar to the case where the nonmagnetic coupling layer 103 was provided as shown in FIG. 3 was recognized. From these results, the nonmagnetic coupling layer 103 is not essential.

[Experimental example 2]
Except for the composition of the ferromagnetic intermediate layer 107 of Experimental Example 1, Experimental Example 2 has the same medium configuration as Experimental Example 1. In this experimental example, a Cu-20 at.% Co layer was formed as the ferromagnetic intermediate layer 107 in a range of 1.5 to 200 nm at a gas pressure of 6.5 Pa and a film formation rate of 1.5 nm / s. FIG. 5 shows the results of evaluation of this experimental example by the method described in Experimental Example 1. In this experimental example, when the thickness of the intermediate layer 107 was 5 nm or more, it was possible to reduce the reference value of the signal attenuation rate to 25% or less. Furthermore, the signal-to-noise ratio exceeded the reference value of 12.0 dB when the film thickness of the ferromagnetic intermediate layer 107 was 3 nm or more and 100 nm or less.

  Although not shown in the drawing, when the composition of the intermediate layer 107 is such that the total of Co and Fe is 20 at.% And Fe is changed in the range of 0 to 6 at.%, The ferromagnetic intermediate layer 107 is also changed. In the range of 5 nm to 100 nm, the signal attenuation rate and the signal-to-noise ratio were over 12.0 dB, and the number of corrosion points also satisfied the standard value.

[Experimental Example 3]
Experimental Example 3 has the same medium configuration except that the composition of the ferromagnetic intermediate layer 107 of Experimental Example 1 is changed. In Experimental Example 3, a Cu-20 at.% Fe layer was formed in the range of 1.5 to 200 nm at a gas pressure of 6.5 Pa and a film formation rate of 1.5 nm / s. FIG. 6 shows the results of evaluating the magnetic recording medium of Experimental Example 3 by the method described in Experimental Example 1. In this experimental example, when the film thickness of the ferromagnetic intermediate layer was 5 nm or more, it was possible to reduce the reference value of the signal attenuation rate to 25% or less. Furthermore, the signal-to-noise ratio exceeded the reference value of 12.0 dB when the film thickness of the ferromagnetic intermediate layer 107 was 3 nm or more and 100 nm or less.

  Although not shown in the figure, when the composition of the intermediate layer 107 is such that the ratio of Co and Fe is 20 at.% And Fe is changed in the range of 6 to 20 at.%, The ferromagnetic intermediate layer 107 is also changed. In the range of 5 nm to 100 nm, the signal attenuation rate and the signal-to-noise ratio were over 12.0 dB, and the number of corrosion points also satisfied the standard value.

[Experimental Example 4]
The configuration of Experimental Example 4 is the same medium configuration except that the composition of the ferromagnetic intermediate layer 107 of Experimental Example 1 is changed. In this experimental example, the ferromagnetic intermediate layer 107 was formed to a thickness of 30 nm at a gas pressure of 6.5 Pa and a film formation rate of 1.5 nm / s, and the composition was as follows.
(Experimental example 401) Cu
(Experimental example 402) Cu-7 at.% Co-3 at.% Fe
(Experimental example 403) Cu-14 at.% Co-6 at.% Fe
(Experimental Example 404) Cu-21 at.% Co-9 at.% Fe
(Experimental example 405) Cu-24.5at.% Co-10.5at.% Fe
(Experimental example 406) Cu-28at.% Co-12at.% Fe
(Experimental example 407) Cu-35at.% Co-15at.% Fe

  FIG. 7 shows the signal noise ratio and the signal attenuation rate of Experimental Example 4 using these compositions. When the ratio of the total of Co and Fe is in the range of 10 at. Moreover, as a result of evaluating the corrosion resistance of Experimental Example 4 by the method shown in Experimental Example 1, the corrosion score of all the media was lower than the standard 75.

  Although not shown in the figure, as a result of evaluating the intermediate layer with a composition similar to that of Experimental Examples 401 to 407 in a film thickness range of 5 to 100 nm, the ratio of the total amount of Co and Fe is 10 at. In the range of 30 at.% Or less, all the standard values of the signal noise ratio, the signal attenuation rate, and the corrosion resistance were satisfied.

[Experimental Example 5]
The configuration of the magnetic recording medium of Experimental Example 5 will be described with reference to FIG. Adhesion layer 101, soft magnetic backing layer 102, nonmagnetic coupling layer 103, soft magnetic backing layer 104, seed layer 105, nonmagnetic intermediate layer 106, ferromagnetic intermediate layer 501, nonmagnetic intermediate layer 502, strong on substrate 100 The magnetic intermediate layer 503, the recording layers (108, 109), and the protective layer 110 are stacked. A lubricating film may be formed on the protective film 110. Further, a similar magnetic recording medium may be configured on both surfaces of the substrate 100.
This medium configuration is the same as that of Experimental Example 1 except for the ferromagnetic intermediate layers 501 and 503 and the nonmagnetic intermediate layer 502.

In Experimental Example 5, the compositions of the ferromagnetic intermediate layers 501 and 503 are the same as those used in Experimental Example 4 as follows, and the respective film thicknesses are obtained at a gas pressure of 6.5 Pa and a film forming rate of 1.5 nm / s. 15 nm was laminated. As the nonmagnetic intermediate layer 502, a Ru layer was formed to 5 nm at a gas pressure of 6.5 Pa and a film formation rate of 1.5 nm / s.
(Experiment 501) Cu
(Experimental example 502) Cu-7 at.% Co-3 at.% Fe
(Experimental example 503) Cu-14 at.% Co-6 at.% Fe
(Experimental example 504) Cu-21 at.% Co-9 at.% Fe
(Experimental example 505) Cu-24.5at.% Co-10.5at.% Fe
(Experimental example 506) Cu-28 at.% Co-12 at.% Fe
(Experimental example 507) Cu-35at.% Co-15at.% Fe
(Experimental example 508) Cu-42at.% Co-18at.% Fe
(Experimental example 509) Cu-49 at.% Co-21 at.% Fe
The difference between Experimental Example 5 and Experimental Example 4 is the presence or absence of the nonmagnetic intermediate layer 502 and the ferromagnetic intermediate layer 503.

  The signal-to-noise ratio measured for these magnetic recording media is shown in FIG. In Experimental Example 4, the signal-to-noise ratio is reduced when the ratio of the total of Co and Fe is 35 at.% Or more. In Experimental Example 5, the signal-to-noise ratio is 12. Reference values of 0 dB or more, a signal decrease rate of 25% or less, and a corrosion point of 75 or less were achieved.

[Experimental Example 6]
The configuration of the magnetic recording medium of Experimental Example 6 will be described with reference to FIG. An adhesion layer 101, a soft magnetic backing layer 102, a nonmagnetic coupling layer 103, a soft magnetic backing layer 104, a seed layer 105, a nonmagnetic intermediate layer 106, and a ferromagnetic intermediate layer 601 are laminated on the substrate 100, and further a nonmagnetic intermediate layer is laminated. In this structure, the ferromagnetic intermediate layer 603 is laminated for 2 to 5 periods from the layer 602, and the recording layers (108, 109) and the protective layer 110 are laminated thereon.

A lubricating film may be formed on the protective film 110. Further, a similar magnetic recording medium may be configured on both surfaces of the substrate 100.
This medium configuration is the same as that of Experimental Example 5 except for the layer between the ferromagnetic intermediate layer 601 and the ferromagnetic intermediate layer 603.

The ferromagnetic intermediate layers 601 and 603 have a total film thickness of 15 to 100 nm and uniform thicknesses. The ratio of the total amount of Co and Fe is 10 to 60 at.%, The gas pressure is 6.5 Pa, and the film formation rate is 1.5 nm. / S. As the nonmagnetic intermediate layer 602, a Ru layer was formed by 5 nm at a gas pressure of 6.5 Pa and a film formation rate of 1.5 nm / s.
As a result of evaluating these experimental examples, reference values were achieved in the signal-to-noise ratio, the signal decrease rate, and the number of corrosion points.

[Experimental Example 7]
The medium configuration of Experimental Example 7 will be described with reference to FIG. In the magnetic recording medium of Experimental Example 7, an adhesion layer 101, a soft magnetic backing layer 102, a nonmagnetic coupling layer 103, a soft magnetic backing layer 104, a seed layer 105, and a nonmagnetic intermediate layer 106 are stacked on a substrate 100, and The ferromagnetic intermediate layer 701, the nonmagnetic intermediate layer 702, the recording layers (108, 109), and the protective layer 110 are stacked. A lubricating film was formed on the protective film 110. A similar magnetic recording medium may be formed on both sides of the substrate 100.

  This medium configuration is the same as that of Experimental Example 1 except for the nonmagnetic intermediate layer 702. In Experimental Example 7, the ferromagnetic intermediate layer 701 was formed of a Cu-21 at.% Co-9 at.% Fe layer with a film thickness of 30 nm. The nonmagnetic intermediate layer 702 was formed by forming a Ru layer with a gas pressure of 6.5 Pa, a film formation rate of 1.5 nm / s, and a thickness of 1 to 30 nm.

  The evaluation results for these magnetic recording media are shown in FIG. The signal noise ratio and the number of corrosion points all satisfy the standard values. The signal attenuation rate satisfied the reference value of 25% or less when the film thickness of the nonmagnetic intermediate layer 702 was 20 nm or less. Further, when the film thickness of the nonmagnetic intermediate layer 702 is 20 nm or less, the ferromagnetic intermediate layer 701 was evaluated by changing the film thickness in the range of 5 to 100 nm. As a result, the total ratio of Co and Fe was 10 at. Within the range of% or less, all the standard values of the signal-to-noise ratio, the signal attenuation rate, and the corrosion resistance were satisfied.

[Experimental Example 8]
The medium configuration of Experimental Example 8 will be described with reference to FIG. The magnetic recording medium of Experimental Example 8 has a structure in which an adhesion layer 101, a seed layer 105, a nonmagnetic intermediate layer 106, a ferromagnetic intermediate layer 107, recording layers (108, 109), and a protective layer 110 are stacked on a substrate 100. It is. A lubricating film was formed on the protective film 110. A similar magnetic recording medium may be formed on both sides of the substrate 100.

  This medium configuration is the same as that of Experimental Example 1 except that the soft magnetic backing layers 102 and 104 and the nonmagnetic coupling layer 103 are not provided. In this experimental example, the film thickness of the ferromagnetic intermediate layer 107 was 30 nm.

  As a result of evaluating the medium of this experimental example, the signal attenuation rate and the signal noise ratio were 3% and 12.2 dB, respectively. Even in the evaluation of corrosion resistance, the number of corrosion points was 64. Therefore, it was confirmed that the standard was satisfied from the viewpoint of signal attenuation rate, signal noise ratio, and corrosion resistance.

[Experimental Example 9]
The medium configuration of Experimental Example 9 will be described with reference to FIG. The magnetic recording medium of this experimental example includes an adhesion layer 101, a soft magnetic backing layer 102, a seed layer 105, a nonmagnetic intermediate layer 106, a ferromagnetic intermediate layer 107, a recording layer (108, 109), a protective layer on a substrate 100. 110 is a laminated structure. A lubricating film was formed on the protective film 110. A similar magnetic recording medium may be formed on both sides of the substrate 100.

  This medium configuration is the same as Experimental Example 1 except that the nonmagnetic coupling layer 103 and the soft magnetic backing layer 104 are not provided. In this experimental example, the thickness of the ferromagnetic intermediate layer 107 was 30 nm.

  As a result of evaluation in this experimental example, the standards were satisfied with respect to the signal attenuation rate, the signal noise ratio, and the corrosion resistance. In addition, the reproduction signal obtained after DC demagnetization using the magnetic recording head did not show the occurrence of spike noise due to the flux return path.

[Experimental Example 10]
The medium configuration of Experimental Example 10 will be described with reference to FIG. The magnetic recording medium of this experimental example includes an adhesion layer 101, a soft magnetic backing layer 102, a nonmagnetic coupling layer 103, a soft magnetic backing layer 104, a seed layer 105, a ferromagnetic intermediate layer 107, a recording layer (108) on a substrate 100. 109), and a protective layer 110 is laminated. A lubricating film may be formed on the protective film 110. Further, a similar magnetic recording medium may be configured on both surfaces of the substrate 100.

  This medium configuration is the same as that of Experimental Example 1 except that the nonmagnetic intermediate layer 106 is not provided. In this experimental example, the thickness of the ferromagnetic intermediate layer 107 is 5 to 100 nm, the composition is within the range of the ratio of the total amount of Co and Fe of 10 to 30 at.%, The gas pressure is 6.5 Pa, and the film forming rate is 1.5 nm / s. Formed.

  As a result of evaluating the magnetic recording medium described in this experimental example, the signal attenuation ratio and the signal noise ratio were 0% and 12.0 dB or more, respectively, and the corrosion score was 50 or less in the corrosion resistance evaluation in all film thickness compositions. . Therefore, the standards for the signal attenuation rate, the signal noise ratio, and the corrosion resistance were satisfied.

[Experimental Example 11]
The magnetic recording medium of Experimental Example 11 includes an adhesion layer 101, a soft magnetic backing layer 102, a nonmagnetic coupling layer 103, a soft magnetic backing layer 104, a seed layer 105, a nonmagnetic intermediate layer 106, and a ferromagnetic intermediate layer on a substrate 100. 107, a recording layer (108, 109), and a protective layer 110 are laminated. A lubricating film was formed on the protective film 110. A similar magnetic recording medium may be formed on both sides of the substrate 100.

This medium configuration is the same as that of Experimental Example 1 except for the ferromagnetic intermediate layer 107. In Experimental Example 11, the composition of the ferromagnetic intermediate layer 107 was as follows, and a film thickness of 30 nm was formed at a gas pressure of 6.5 Pa and a film formation rate of 1.5 nm / s.
(Experimental example 1101) Cu-14 at.% Co-6 at.% Fe-5 at% Cr
(Experimental example 1102) Cu-14 at.% Co-6 at.% Fe-5 at% Ru
(Experimental Example 1103) Cu-14 at.% Co-6 at.% Fe-5 at% Ni
In these experimental examples, Cr, Ru, and Ni are added to a medium in which the ferromagnetic intermediate layer 107 in Experimental Example 11 is a Cu-14 at.% Co-6 at.% Fe layer.

  Results of evaluating these magnetic recording media by the method described in Experimental Example 1 are shown in FIG. As is clear from FIG. 16, the medium of this experimental example satisfied the standards for the signal attenuation rate, the signal noise ratio, and the number of corrosion points. In particular, it has been found that when Cr is added to the ferromagnetic intermediate layer 107, the number of corrosion points decreases and a medium having excellent corrosion resistance can be obtained.

DESCRIPTION OF SYMBOLS 100 ... Substrate, 101 ... Adhesion layer, 102 ... First soft magnetic backing layer, 103 ... Nonmagnetic coupling layer, 104 ... Second soft magnetic backing layer, 105 ... Seed layer, 106 ... Nonmagnetic intermediate layer, 107 ... Ferromagnetic intermediate layer 108 ... first recording layer 109 ... second recording layer 110 ... protective layer 501 ... ferromagnetic intermediate layer 502 ... nonmagnetic intermediate layer 503 ... ferromagnetic intermediate layer 601 ... strong Magnetic intermediate layer, 602 ... Nonmagnetic intermediate layer, 603 ... Ferromagnetic intermediate layer, 701 ... Ferromagnetic intermediate layer, 702 ... Nonmagnetic intermediate layer

Claims (6)

In a perpendicular magnetic recording medium comprising an intermediate layer and a magnetic recording layer on a substrate,
The intermediate layer contains Cu as a main component and contains at least one element selected from Co and Fe, the total ratio of Co and Fe is 10 to 30 at.%, And the film thickness is 5 to 100 nm. Perpendicular magnetic recording medium. In a perpendicular magnetic recording medium comprising an intermediate layer and a magnetic recording layer on a substrate,
The intermediate layer has a structure in which a first intermediate layer and a second intermediate layer are sequentially stacked as viewed from the substrate side,
The first intermediate layer contains Ru or a Ru alloy,
The second intermediate layer is composed of an alloy containing Cu as a main component and containing at least one element selected from Co and Fe, and having a total ratio of Co and Fe of 10 to 30 at.%, And a film thickness of 5 nm to 100 nm. A perpendicular magnetic recording medium characterized by the above. In a perpendicular magnetic recording medium comprising an intermediate layer and a magnetic recording layer on a substrate,
The intermediate layer has a structure in which a first intermediate layer, a second intermediate layer, a third intermediate layer, and a fourth intermediate layer are sequentially stacked when viewed from the substrate side,
The first intermediate layer and the third intermediate layer contain Ru or a Ru alloy,
The second intermediate layer and the fourth intermediate layer are made of an alloy containing Cu as a main component and containing at least one element selected from Co and Fe, and a total ratio of Co and Fe of 10 to 60 at.%.
A perpendicular magnetic recording medium, wherein a total film thickness of the second intermediate layer and the fourth intermediate layer is 15 nm or more and 100 nm or less. In a perpendicular magnetic recording medium comprising an intermediate layer and a magnetic recording layer on a substrate,
The intermediate layer has a laminated structure composed of an even number of 6 to 12 layers,
The odd-numbered intermediate layer when viewed from the substrate side contains Ru or a Ru alloy,
The even-numbered intermediate layer as viewed from the substrate side is made of an alloy containing Cu as a main component and containing at least one element selected from Co and Fe, and a total ratio of Co and Fe of 10 to 60 at.%.
A perpendicular magnetic recording medium, wherein the total thickness of the even-numbered intermediate layers is 15 nm or more and 100 nm or less. In a perpendicular magnetic recording medium comprising an intermediate layer and a magnetic recording layer on a substrate,
The intermediate layer has a structure in which a first intermediate layer, a second intermediate layer, and a third intermediate layer are sequentially stacked as viewed from the substrate side,
The first intermediate layer and the third intermediate layer contain Ru or a Ru alloy,
The second intermediate layer is composed of an alloy containing Cu as a main component and containing at least one element selected from Co and Fe, and a total ratio of Co and Fe of 10 to 30 at.%.
A perpendicular magnetic recording medium, wherein the second intermediate layer has a thickness of 5 to 100 nm, and the third intermediate layer has a thickness of 20 nm or less.   6. The perpendicular magnetic recording medium according to claim 1, wherein the intermediate layer containing at least one element selected from Co and Fe and containing Cu as a main component contains at least one additive element selected from Ni, Ru, and Cr. A perpendicular magnetic recording medium comprising:

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