JP5787273B2 - Soft magnetic underlayer film for magnetic recording medium, sputtering target material for forming soft magnetic underlayer film for magnetic recording medium, and method for producing soft magnetic underlayer film for magnetic recording medium - Google Patents

Description

  The present invention relates to a soft magnetic underlayer film of a Co—Fe-based alloy used for a magnetic recording medium, a sputtering target material for forming a soft magnetic underlayer film, and a method for producing a soft magnetic underlayer film.

  In recent years, high recording density has been strongly demanded by an advanced information society. As a technique for realizing this high density, a perpendicular magnetic recording system has been put into practical use instead of the conventional in-plane magnetic recording system.

  Perpendicular magnetic recording is a method in which the magnetic film of a perpendicular magnetic recording medium is formed so that the axis of easy magnetization is oriented perpendicularly to the medium surface. This is a method suitable for high recording density with a small decrease in recording and reproduction characteristics. In the perpendicular magnetic recording system, a recording medium having a magnetic recording layer film and a soft magnetic underlayer film with improved recording sensitivity has been developed.

The soft magnetic underlayer film of such a magnetic recording medium has a high saturation magnetic flux density in order to draw a recording magnetic field efficiently, and has a high magnetic permeability in order to improve the writing property to the magnetic recording medium. (See, for example, Patent Documents 1 and 2). Further, the soft magnetic underlayer film is required to have an amorphous structure in order to prevent an increase in surface roughness and to reduce the flying height of the head (see, for example, Patent Document 3).
In addition, as a conventional soft magnetic underlayer film, a Co—Fe—Al alloy (for example, see Patent Document 4) or a Co—Fe—Ni alloy (for example, Patent Document) having a high saturation magnetic flux density and high corrosion resistance. 5) has been proposed.

JP 2006-190486 A Japanese Patent No. 4490985 JP 2008-276859 A Japanese Patent No. 4101836 International Publication No. 2010/007980

The alloy composition of the soft magnetic underlayer film disclosed in Patent Documents 1 and 2 described above is a Co alloy such as a Co—Ta—Zr alloy or a Co—Nb—Zr alloy, or an Fe alloy, and has a high magnetic permeability but is saturated. It is an alloy having a low magnetic flux density, or an alloy having a high saturation magnetic flux density but a low magnetic permeability.
Further, the soft magnetic underlayer film specifically disclosed in Patent Document 4 has a high saturation magnetic flux density at Co: Fe = 44: 56 to 78:22 in atomic%, but has a low magnetic permeability.
Further, the soft magnetic underlayer alloy specifically disclosed in Patent Document 5 is a Co—Fe—Ni alloy having a high Fe content or a high Ni content, and has a high saturation magnetic flux density but a high magnetic permeability. It is a low alloy or an alloy with high permeability but low saturation magnetic flux density.
An object of the present invention is to provide a soft magnetic underlayer film for a magnetic recording medium having an amorphous structure capable of achieving both a saturation magnetic flux density and a magnetic permeability that have not been studied so far at a high level.

  The present inventors have made various studies on the composition ratio of Co and Fe, the additive element to the Co—Fe alloy, and the range of addition of the Co—Fe alloy soft magnetic underlayer film used in the magnetic recording medium. As a result, the inventors have found a composition range suitable for an amorphous soft magnetic underlayer film having both a high saturation magnetic flux density and a high magnetic permeability, and have reached the present invention.

That is, the present invention is a soft magnetic underlayer film for a magnetic recording medium made of a Co—Fe-based alloy, wherein the ratio of the composition of Co and Fe expressed in atomic% in the soft magnetic underlayer film is 88: One or two selected from the group consisting of 12 to 92: 8 and an additive element of 3.0 atomic% or more of Zr and 2.0 atomic% or more of B, Y, Nb, Hf, Ta A soft magnetic underlayer film for a magnetic recording medium containing any of the above elements and having a total content of the additive elements in the range of 5.0 to 9.0 atomic%.
The Co—Fe-based alloy is a soft magnetic underlayer film for a magnetic recording medium in which a part of Co is substituted with Ni so that Ni / (Co + Ni) ≦ 0.1 in atomic percent.
The present invention also provides a sputtering target material for forming a soft magnetic underlayer film for a magnetic recording medium made of a Co—Fe-based alloy, the composition of Co and Fe expressed in atomic% in the soft magnetic underlayer film. Is in the range of 88:12 to 92: 8, and is selected from the group of 3.0 atomic% or more of Zr and 2.0 atomic% or more of B, Y, Nb, Hf, and Ta as the additive element. A soft magnetic underlayer for a magnetic recording medium containing one or more elements, and the total content of the additional elements is in the range of 5.0 to 9.0 atomic% It is a film-forming target material, and a soft for magnetic recording medium in which a part of Co is substituted with Ni so that the Co—Fe alloy satisfies Ni / (Co + Ni) ≦ 0.1 in atomic%. A sputtering target material for forming a magnetic underlayer film.
Moreover, this invention is a manufacturing method of the soft-magnetic underlayer film for magnetic recording media formed by sputtering method using the said sputtering target material.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a soft magnetic underlayer film of a Co-Fe based alloy used for an amorphous structure magnetic recording medium that has both a high saturation magnetic flux density and a high magnetic permeability, which is extremely effective in manufacturing a perpendicular magnetic recording medium. Technology.

  The most important feature of the present invention is that an optimum composition range for realizing an amorphous structure film having both a high saturation magnetic flux density and a high magnetic permeability is found as a soft magnetic underlayer film.

First, the Co—Fe alloy as the base of the present invention will be described.
The Co—Fe alloy used as the base of the alloy of the present invention has a composition in which the ratio of the composition of Co and Fe expressed in atomic% is in the range of 88:12 to 92: 8. In the alloy composition containing Co and Fe, the content of Fe with respect to Co is set to 8 to 12 atomic% while keeping the saturation magnetic flux density of the Co—Fe alloy film high by making this composition range. This is because magnetostriction can be reduced and the magnetic permeability can be increased. When the Fe content is less than 8 atomic%, the saturation magnetic flux density is greatly decreased. When the content exceeds 12 atomic%, the magnetostriction is increased and the magnetic permeability is decreased. It is important to control to the range of%.

  The Co—Fe-based alloy of the soft magnetic underlayer film of the present invention includes the above-described Co—Fe alloy with an addition element of 3.0 atomic% or more of Zr and 2.0 atomic% or more of B, Y, Nb, One or two or more elements selected from the group of Hf and Ta are contained, and the total content of the additive elements is in the range of 5.0 to 9.0 atomic%. The reason why the addition of 3.0 atomic% or more of Zr is essential is that Zr has a particularly high ability to form an amorphous phase with respect to a Co—Fe alloy, and can be made amorphous by adding a small amount. In addition, since containing Zr alone is not sufficient for promoting the amorphization, it is further one or two or more selected from the group of B, Y, Nb, Hf, Ta of 2.0 atomic% or more. These elements are included in a composite manner. By containing B, Y, Nb, Hf, and Ta together with Zr, it becomes possible to significantly promote the amorphization of the soft magnetic underlayer film of the Co—Fe based alloy. When the total amount of addition of Zr and an element selected from the group of B, Y, Nb, Hf, and Ta is less than 5.0 atomic%, the soft magnetic underlayer film of the Co—Fe alloy Amorphization becomes difficult, and when the total amount of addition exceeds 9.0 atomic%, the saturation magnetic flux density decreases greatly. Therefore, it is important to control within the range of 5.0 to 9.0 atomic%. The amount of Zr added is preferably 4.0 atomic% or more in order to promote the amorphization of the soft magnetic underlayer film.

  Further, in the Co—Fe alloy of the soft magnetic underlayer film of the present invention, it is desirable to replace a part of Co with Ni so that Ni / (Co + Ni) ≦ 0.1 is satisfied in atomic%. This is because by replacing a part of Co with Ni in this range, the corrosion resistance of the soft magnetic underlayer film can be improved while maintaining a high saturation magnetic flux density and a high magnetic permeability. Note that, when Ni is contained exceeding the above range, the saturation magnetic flux density of the Co—Fe alloy is remarkably lowered. Therefore, when Ni is added, it is desirable to control the content within this range.

  In addition, in the Co—Fe based alloy of the soft magnetic underlayer film of the present invention, one or more elements selected from the group of Ti, V, Mo and W are added in order to improve the corrosion resistance as a film. It is also possible to do. However, if Ti, V, Mo, and W are added in a large amount, the saturation magnetic flux density is greatly reduced. Therefore, the addition amount is desirably 5.0 atomic% or less.

  The soft magnetic underlayer film of the present invention has a high saturation magnetic flux density of 1.4 T or more in order to efficiently draw a recording magnetic field, and a high maximum ratio of 5000 or more in order to improve the writability to the magnetic recording medium. It is desirable to have magnetic permeability.

  As a method for forming the above-described Co—Fe-based soft magnetic underlayer film, a vacuum deposition method, a sputtering method, and a chemical vapor deposition method can be used. Among these, a sputtering method in which a thin film is formed by sputtering a target material having the same composition as that of the soft magnetic underlayer film of a Co—Fe-based alloy is preferable because a stable film can be formed at high speed.

  As a manufacturing method of the sputtering target material used for forming the soft magnetic underlayer film of the Co—Fe-based alloy described above, a melt casting method or a powder sintering method can be applied. In the melt casting method, it is possible to produce a cast ingot or a bulk body obtained by applying plastic processing or pressure processing to the cast ingot. Moreover, in the powder sintering method, an alloy powder having the final composition of the Co—Fe based alloy is manufactured by a gas atomizing method and used as a raw material powder, or a plurality of alloy powders and pure metal powders are combined with the final composition of the Co—Fe based alloy The mixed powder thus mixed can be used as a raw material powder. As a method for sintering the raw material powder, it is possible to use pressure sintering such as hot isostatic pressing, hot pressing, discharge plasma sintering, and extrusion press sintering.

The following examples further illustrate the present invention.
Example 1
Each gas atomized powder with a 99.9% purity Co, Co ₉₀ -Zr ₁₀ (atomic%), Co ₉₀ -Nb ₂₀ (atomic%), and Fe ₉₀ -Zr ₁₀ (atomic%) alloy composition was prepared, and (Co _{90 -Fe 10) 92 -Nb 3 -Zr} 5 ( atomic%) so that the alloy composition, weighed and mixed to prepare a mixed powder. The obtained mixed powder was filled in a mild steel capsule and sealed by deaeration, and then sintered by hot isostatic pressing under conditions of a temperature of 950 ° C., a pressure of 122 MPa, and a holding time of 1 hour to prepare a sintered body. The obtained sintered body was machined to produce a Co—Fe based alloy sputtering target material having a diameter of 180 mm × thickness of 5 mm.
The target material prepared above is placed in a chamber of a DC magnetron sputtering apparatus (3010 manufactured by Anerva), and the inside of the chamber is evacuated to a vacuum level of 2 × 10 ⁻⁵ Pa or less, and then a size of 75 × 25 mm. A soft magnetic underlayer film having a thickness of 200 nm was formed on the glass substrate. In addition, a soft magnetic backing layer film having a thickness of 300 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were Ar gas pressure 0.6 Pa and input power 500 W.

(Comparative Example 1)
A gas atomized powder having a purity of 99.9% (Co ₇₀ —Fe ₃₀ ) ₉₀ —Ta ₃ —Zr ₅ —Al ₂ (atomic%) alloy composition was filled into a mild steel capsule, degassed and sealed, and then at a temperature of 950 ° C. Sintered by hot isostatic pressing under the conditions of a pressure of 122 MPa and a holding time of 1 hour to prepare a sintered body. The obtained sintered body was machined to produce a Co—Fe based alloy sputtering target material having a diameter of 180 mm × thickness of 5 mm. And using the produced target material, the soft-magnetic backing layer film | membrane with a film thickness of 200 nm was formed on the glass substrate of a dimension 75x25 mm. In addition, a soft magnetic backing layer film having a thickness of 300 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were the same as in Example 1.

(Comparative Example 2)
Using a raw material with a purity of 99.9%, a molten alloy having a composition of (Co ₈₀ —Fe ₁₀ —Ni ₁₀ ) ₉₂ —Nb ₃ —Zr ₅ (atomic%) was vacuum-melted, and the outer diameter was 280 mm and the inner diameter was 200 mm on a Cu surface plate. The ingot was produced by casting in a mold provided with a cast iron ring having a height of 25 mm. Then, machining was performed to obtain a Co—Fe based alloy target material having a diameter of 190 mm × thickness of 5 mm. And using the produced target material, the soft-magnetic backing layer film | membrane with a film thickness of 200 nm was formed on the glass substrate of a dimension 75x25 mm. In addition, a soft magnetic backing layer film having a thickness of 300 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were the same as in Example 1.

  Using the Rigaku X-ray diffractometer RINT2500V for the samples of the soft magnetic underlayer films of Example 1, Comparative Example 1 and Comparative Example 2 formed on the glass substrate (dimension 75 × 25 mm) as described above, a radiation source X-ray diffraction measurement was performed using Co. As a result, the X-ray diffraction patterns obtained in all the samples were broad peaks, and it was confirmed that the soft magnetic underlayer film had an amorphous structure.

  Next, with respect to the samples of the soft magnetic underlayer films of Example 1, Comparative Example 1 and Comparative Example 2 formed on the glass substrate (φ10 mm) as described above, the vibration sample type magnetometer VSM-5 manufactured by Toei Kogyo Co., Ltd. Using a -15 type, the BH curve in the in-plane direction was measured. The saturation magnetic flux density was determined from the BH curve with the maximum applied magnetic field of 8000 A / m, and the maximum relative magnetic permeability was determined from the BH curve with the maximum applied magnetic field of 800 A / m. The results are shown in Table 1.

  From Table 1, the soft magnetic underlayer film of the Co—Fe-based alloy of Example 1 of the present invention has a high saturation magnetic flux density of 1.60 T, and the maximum relative magnetic permeability is also high as 18000. It can be seen that a high saturation magnetic flux density and a high magnetic permeability can be realized while having an amorphous structure. On the other hand, the soft magnetic underlayer film of the Co—Fe-based alloy of Comparative Example 1 has a low maximum relative magnetic permeability because of the large Fe content of Fe: Co = 30: 70, and the Co—Fe of Comparative Example 2 It can be seen that the soft magnetic underlayer film of the alloy is high in maximum relative magnetic permeability due to the Ni content but has a low saturation magnetic flux density due to the high Ni content in contrast to Co.

(Example 2)
Each gas atomized powder having a 99.9% purity Co, Co ₉₀ -Ta ₁₀ -Zr ₂ (atomic%), Co ₉₀ -Zr ₁₀ (atomic%), and Fe ₉₀ -Zr ₁₀ (atomic%) alloy composition was prepared. , (Co ₉₂ -Fe ₈ ) ₉₂ -Ta ₃ -Zr ₅ (atomic%) were weighed and mixed to produce a mixed powder so as to have an alloy composition. The obtained mixed powder was filled in a mild steel capsule and sealed by deaeration, and then sintered by hot isostatic pressing under conditions of a temperature of 950 ° C., a pressure of 122 MPa, and a holding time of 1 hour to prepare a sintered body. The obtained sintered body was machined to produce a Co—Fe based alloy sputtering target material having a diameter of 180 mm and a thickness of 4 mm.
The target material prepared above is placed in a chamber of a DC magnetron sputtering apparatus (3010 manufactured by Anerva), and the inside of the chamber is evacuated to a vacuum level of 2 × 10 ⁻⁵ Pa or less, and then a size of 75 × 25 mm. A soft magnetic underlayer film having a thickness of 40 nm was formed on the glass substrate. In addition, a soft magnetic backing layer film having a thickness of 40 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were Ar gas pressure 0.6 Pa and input power 1000 W.

(Example 3)
Each gas atomized powder having a purity of 99.9%, Co ₉₀ -Zr ₁₀ (atomic%), Co ₈₈ -B ₁₂ (atomic%), Fe ₉₀ -Zr ₁₀ (atomic%) alloy composition and purity of 99.9% prepare the Ni _{powder, (Co 85 -Fe 12 -Ni 3} ) 92 -Zr 5 -B 3 ( atomic%) so that the alloy composition, weighed and mixed to prepare a mixed powder. The obtained mixed powder was filled in a mild steel capsule and sealed by deaeration, and then sintered by hot isostatic pressing under conditions of a temperature of 950 ° C., a pressure of 122 MPa, and a holding time of 1 hour to prepare a sintered body. The obtained sintered body was machined to produce a Co—Fe based alloy sputtering target material having a diameter of 180 mm and a thickness of 4 mm.
The target material prepared above is placed in a chamber of a DC magnetron sputtering apparatus (3010 manufactured by Anerva), and the inside of the chamber is evacuated to a vacuum level of 2 × 10 ⁻⁵ Pa or less, and then a size of 75 × 25 mm. A soft magnetic underlayer film having a thickness of 40 nm was formed on the glass substrate. In addition, a soft magnetic backing layer film having a thickness of 40 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were the same as in Example 2.

Example 4
Each gas atomized powder having a purity of 99.9% Co, Co ₉₀ -Zr ₁₀ (atomic%), Co ₈₀ -Nb ₂₀ (atomic%), Fe ₉₀ -Zr ₁₀ (atomic%) alloy composition and purity 99.9% prepare the Ni _{powder, (Co 85 -Fe 10 -Ni 5} ) 92 -Nb 3 -Zr 5 ( atomic%) so that the alloy composition, weighed and mixed to prepare a mixed powder. The obtained mixed powder was filled in a mild steel capsule and sealed by deaeration, and then sintered by hot isostatic pressing under conditions of a temperature of 950 ° C., a pressure of 122 MPa, and a holding time of 1 hour to prepare a sintered body. The obtained sintered body was machined to produce a Co—Fe based alloy sputtering target material having a diameter of 180 mm and a thickness of 4 mm.
The target material prepared above is placed in a chamber of a DC magnetron sputtering apparatus (3010 manufactured by Anerva), and the inside of the chamber is evacuated to a vacuum level of 2 × 10 ⁻⁵ Pa or less, and then a size of 75 × 25 mm. A soft magnetic underlayer film having a thickness of 40 nm was formed on the glass substrate. In addition, a soft magnetic backing layer film having a thickness of 40 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were the same as in Example 2.

(Example 5)
Each gas atomized powder having a 99.9% purity Co, Co ₉₀ -Ta ₁₀ -Zr ₂ (atomic%), Co ₉₀ -Zr ₁₀ (atomic%), and Fe ₉₀ -Zr ₁₀ (atomic%) alloy composition was prepared. , (Co ₉₀ -Fe ₁₀ ) ₉₂ -Ta ₃ -Zr ₅ (atomic%) were weighed and mixed to produce a mixed powder. The obtained mixed powder was filled in a mild steel capsule and sealed by deaeration, and then sintered by hot isostatic pressing under conditions of a temperature of 950 ° C., a pressure of 122 MPa, and a holding time of 1 hour to prepare a sintered body. The obtained sintered body was machined to produce a Co—Fe based alloy sputtering target material having a diameter of 180 mm and a thickness of 4 mm.
The target material prepared above is placed in a chamber of a DC magnetron sputtering apparatus (3010 manufactured by Anerva), and the inside of the chamber is evacuated to a vacuum level of 2 × 10 ⁻⁵ Pa or less, and then a size of 75 × 25 mm. A soft magnetic underlayer film having a thickness of 40 nm was formed on the glass substrate. In addition, a soft magnetic backing layer film having a thickness of 40 nm was formed on a glass substrate having a size of φ10 mm.
The sputtering conditions were the same as in Example 2.

(Example 6)
An alloy melt having a composition of 99.9% purity (Co ₉₀ -Fe ₁₀ ) ₉₂ -Zr ₅ -B ₃ (atomic%) was vacuum-dissolved, and an outer diameter of 280 mm, an inner diameter of 200 mm, and a height on a Cu surface plate An ingot was produced by casting in a mold provided with a 25 mm cast iron ring. Then, machining was performed to obtain a Co—Fe based alloy target material having a diameter of 190 mm × thickness of 4 mm. And using the produced target material, the 40-nm-thick soft magnetic backing layer film | membrane was formed on the glass substrate of a dimension 75x25 mm. In addition, a soft magnetic backing layer film having a thickness of 40 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were the same as in Example 2.

(Example 7)
Using a raw material with a purity of 99.9%, a molten alloy having a composition of (Co ₉₀ -Fe ₁₀ ) ₉₃ -Zr ₅ -B ₂ (atomic%) was vacuum-dissolved, and an outer diameter of 280 mm, an inner diameter of 200 mm, and a height on a Cu surface plate An ingot was produced by casting in a mold provided with a 25 mm cast iron ring. Then, machining was performed to obtain a Co—Fe based alloy target material having a diameter of 190 mm × thickness of 4 mm. And using the produced target material, the 40-nm-thick soft-magnetic backing layer film | membrane was formed on the glass substrate of a dimension 75x25 mm. In addition, a soft magnetic backing layer film having a thickness of 40 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were the same as in Example 2.

(Example 8)
Using a raw material with a purity of 99.9%, a molten alloy having a composition of (Co ₉₀ -Fe ₁₀ ) ₉₄ -Zr ₄ -B ₂ (atomic%) was vacuum-dissolved, and an outer diameter of 280 mm, an inner diameter of 200 mm, and a height on a Cu surface plate An ingot was produced by casting in a mold provided with a 25 mm cast iron ring. Then, machining was performed to obtain a Co—Fe based alloy target material having a diameter of 190 mm × thickness of 4 mm. And using the produced target material, the 40-nm-thick soft-magnetic backing layer film | membrane was formed on the glass substrate of a dimension 75x25 mm. In addition, a soft magnetic backing layer film having a thickness of 40 nm was formed on a glass substrate having a size of φ10 mm. The sputtering conditions were the same as in Example 2.

(Comparative Example 3)
Each gas atomized powder having a 99.9% purity Co, Co ₉₀ -Zr ₁₀ (atomic%), Co ₈₈ -B ₁₂ (atomic%), Fe ₉₀ -Zr ₁₀ (atomic%) alloy composition was prepared, and (Co _{50 -Fe 50) 89 -Zr 6 -B} 5 ( atomic%) so that the alloy composition, weighed and mixed to prepare a mixed powder. The obtained mixed powder was filled in a mild steel capsule and sealed by deaeration, and then sintered by hot isostatic pressing under conditions of a temperature of 950 ° C., a pressure of 122 MPa, and a holding time of 1 hour to prepare a sintered body. The obtained sintered body was machined to produce a Co—Fe based alloy sputtering target material having a diameter of 180 mm and a thickness of 4 mm.
The target material prepared above is placed in a chamber of a DC magnetron sputtering apparatus (3010 manufactured by Anerva), and the inside of the chamber is evacuated to a vacuum level of 2 × 10 ⁻⁵ Pa or less, and then a size of 75 × 25 mm. A soft magnetic underlayer film having a thickness of 40 nm was formed on the glass substrate. In addition, a soft magnetic backing layer film having a thickness of 40 nm was formed on a glass substrate having a size of φ10 mm.
The sputtering conditions were the same as in Example 2.

  Soft magnetic backing layer of Example 2, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, and Comparative Example 3 formed on a glass substrate (dimension 75 × 25 mm) as described above The film sample was subjected to X-ray diffraction measurement using Rigaku X-ray diffraction apparatus RINT2500V and Co as the radiation source. As a result, the X-ray diffraction patterns obtained in all the samples were broad peaks, and it was confirmed that the soft magnetic underlayer film had an amorphous structure.

  Next, the soft magnetic backing layers of Example 2, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, and Comparative Example 3 formed on the glass substrate (φ10 mm) as described above. For the film sample, a BH curve in the in-plane direction was measured using a vibrating sample magnetometer VSM-5-15 manufactured by Toei Kogyo Co., Ltd. The saturation magnetic flux density was determined from the BH curve with the maximum applied magnetic field of 8000 A / m, and the maximum relative magnetic permeability was determined from the BH curve with the maximum applied magnetic field of 800 A / m. The results are shown in Table 2.

  From Table 2, the soft magnetic backing layer films of the Co—Fe based alloys of Examples 2, 3, 4, 5, 6, 7, and 8 of the present invention are: It can be seen that it has a high saturation magnetic flux density of 40T or higher and a maximum relative magnetic permeability of a high value of 5000 or higher, and has a high saturation magnetic flux density and high magnetic permeability after having an amorphous structure. . On the other hand, it can be seen that the soft magnetic underlayer film of the Co—Fe-based alloy of Comparative Example 3 has a high saturation magnetic flux density but a low maximum relative magnetic permeability because of the high Fe content of Fe: Co = 50: 50.

  Since the soft magnetic underlayer film of the Co—Fe-based alloy of the present invention has a high saturation magnetic flux density and a high magnetic permeability, it is useful as a soft magnetic underlayer film for magnetic recording media and can be applied. .

Claims (7)

A soft magnetic underlayer film for a magnetic recording medium made of a Co-Fe alloy,
The ratio of the composition of Co and Fe expressed in atomic% in the soft magnetic underlayer film is in the range of 88:12 to 92: 8;
As an additive element, both contain 3.0 atomic% or more of Zr and 2.0 atomic% or more of one or more elements selected from the group of B, Y, Nb, Hf, and Ta. ,
And, when the total content of the additional element is the Co, the sum of 100 atomic% of the Fe, and the additive element, 5.0 to 8. A soft magnetic underlayer film for a magnetic recording medium, characterized by being in the range of 0 atomic%.   2. The soft magnetic underlayer film for a magnetic recording medium according to claim 1, wherein a part of Co is substituted with Ni so as to satisfy Ni / (Co + Ni) ≦ 0.1 in atomic%.   3. The soft magnetic underlayer film for a magnetic recording medium according to claim 1, which has a saturation magnetic flux density of 1.4 T or more and a maximum relative permeability of 5000 or more. A sputtering target material for forming a soft magnetic underlayer film for a magnetic recording medium made of a Co-Fe alloy,
The ratio of the composition of Co and Fe expressed in atomic% in the sputtering target material is in the range of 88:12 to 92: 8;
As an additive element, both contain 3.0 atomic% or more of Zr and 2.0 atomic% or more of one or more elements selected from the group of B, Y, Nb, Hf, and Ta. ,
And, when the total content of the additional element is the Co, the sum of 100 atomic% of the Fe, and the additive element, 5.0 to 8. A sputtering target material for forming a soft magnetic underlayer film for a magnetic recording medium, characterized by being in the range of 0 atomic%.   5. The sputtering for forming a soft magnetic underlayer for a magnetic recording medium according to claim 4, wherein a part of Co is substituted with Ni so as to satisfy Ni / (Co + Ni) ≦ 0.1 in atomic%. Target material.   A method for producing a soft magnetic underlayer film for a magnetic recording medium, comprising forming the soft magnetic underlayer film sputtering target material for a magnetic recording medium according to claim 4 by a sputtering method.   A method for producing a soft magnetic underlayer film for a magnetic recording medium, comprising forming the soft magnetic underlayer film forming sputtering target material for a magnetic recording medium according to claim 5 by a sputtering method.