TW201402835A - Alloy for soft magnetic film layer having low saturation magnetic flux density to be used for magnetic recording medium, and sputtering target material - Google Patents

Abstract

Provided are: an alloy for soft magnetic film layers, which has low saturation magnetic flux density and is to be used in a magnetic recording medium; and a sputtering target material. This alloy contains one or more elements selected from the group consisting of Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Ni, Cu, Al, B, C, Si, P, Zn, Ga, Ge and Sn, with the balance made up of Co and Fe, while satisfying, in at%, the following formulae (1)-(3). (1) 0.50 <= Fe%/(Fe% + Co%) <= 0.90 (2) 5 <= TAM <= 25 (3) 15 <= TAM + TNM <= 25 In this connection, the above-mentioned TAM and TNM are respectively defined as TAM = Y% + Ti% + Zr% + Hf% + V% + Nb% + Ta% + B%/2 and TNM = Cr% + Mo% + W% + Mn% + Ni%/3 + Cu%/3 + Al% + C% + Si% + P% + Zn% + Ga% + Ge% + Sn%.

Description

Alloy for soft magnetic film layer with low saturation magnetic flux density for magnetic recording media and sputtering target

The present application is based on Japanese Patent Application No. 2012-22096, filed on Feb. 3, 2012, the entire disclosure of which is hereby incorporated by reference.

The present invention relates to an alloy for a soft magnetic film layer having a low saturation magnetic flux density for a magnetic recording medium and a sputtering target.

In recent years, due to significant advances in magnetic recording technology, magnetic recording media have advanced toward higher recording densities in order to increase the capacity of the magnetic recording medium, and it is possible to realize a higher magnetic recording density than the conventional in-plane magnetic recording medium. The way has been put into practical use. Furthermore, the method of applying a perpendicular magnetic recording medium using thermal or microwave-assisted recording has also been reviewed.

The above-described perpendicular magnetic recording method is a method in which the easy magnetization axis is formed in such a manner that the medium surface of the magnetic film of the perpendicular magnetic recording medium is disposed in the vertical direction, and is suitable for a method of high recording density. Further, regarding the perpendicular magnetic recording method, a two-layer recording medium having a magnetic recording film layer and a soft magnetic film layer for improving recording sensitivity has been developed. This magnetic recording medium generally uses a CoCrPt-SiO ₂ -based alloy.

Further, a Ru film is generally interposed between the soft magnetic film layers, and the soft magnetic film and the Ru film are combined with an antiferromagnetic (hereinafter referred to as AFC bonding) to have a region insensitive to an external magnetic field (hereinafter referred to as Hbias). ). For example, as disclosed in Japanese Laid-Open Patent Publication No. 2011-86356 (Patent Document 1), it is intended to improve the resistance of a magnetic recording medium to an external noise magnetic field in a use environment. The alloy for a soft magnetic film layer of the present invention can be used in a medium for such perpendicular magnetic recording methods.

Further, in the conventional soft magnetic film layer, it is necessary to have a high saturation magnetic flux density (hereinafter referred to as Bs) and a high amorphous formation energy (hereinafter referred to as amorphous property), and further, according to the use and use of the perpendicular magnetic recording medium. Depending on the environment, various characteristics such as high corrosion resistance and high hardness are required. Among the above-mentioned required characteristics, it is particularly important that high Bs is used, for example, in Patent Document 1 or JP-A-2011-181140 (Patent Document 2) and JP-A-2008-299905 (Patent Document 3). For the goal. The reason why such a high Bs is required is that Bs having a certain value or more is required to stabilize the magnetization of the recording film, and has a large Hbias.

However, the use of a soft magnetic film of high Bs also causes disadvantages. When a soft magnetic film exhibiting a high Bs is used, there is a tendency that Hbias becomes large, and although a high external noise magnetic field resistance is obtained, at the same time, when the magnetic magnetization is recorded, the soft magnetic film has an excessively large magnetic flux to the periphery. A large influence is caused, and the space necessary for writing is increased, resulting in a decrease in recording density. Furthermore, when using a high Hbias film, it is also seen that the magnetization is applied to Hbias or higher. The reaction of applying a magnetic field (hereinafter referred to as magnetization initiation) tends to become dull.

The mode of activation of the magnetization for Hbias and above is shown in Figure 1. When the recording film is magnetized by the general write head, a magnetic field that saturates only the soft magnetic film is applied. Therefore, when the activation of the magnetization becomes dull, it is necessary to apply a magnetic field of a magnitude other than magnetization. As described above, when the magnetization magnetic field becomes large, it is unavoidable that the surrounding area is excessively affected, and as a result, it is difficult to limit the recording to a small area, and the recording density is still lowered. The phenomenon that the above two kinds of recording densities are reduced is also called so-called "unclear writing". Although suppressing one phenomenon has an effect of improving the unclear writing, if the two are suppressed, the effect of writing unclearness is further improved. .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] JP-A-2011-86353

[Patent Document 2] JP-A-2011-181140

[Patent Document 3] JP-A-2008-299905

In order to solve the problem as described above, the inventors of the present invention have actively developed the results, and found that if there is a Bs of 0.5T exceeding the minimum Bs which stabilizes the magnetization of the recording film, it is high even at a lower Bs. Hbias, in addition, a soft magnetic alloy which is also activated by a sharp magnetization with high Hbias, is considered to have high resistance to external magnetic fields and high recording density due to suppression of "unclear writing".

According to the same aspect of the present invention, there is provided an alloy which is an alloy for a soft magnetic film layer in a magnetic recording medium, wherein the alloy comprises Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, One or more selected from the group consisting of Mn, Ni, Cu, Al, B, C, Si, P, Zn, Ga, Ge, and Sn, and the remainder of Co and Fe, and satisfying at at% Equation (1)~(3):

(1) 0.50≦Fe%/(Fe%+Co%)≦0.90

(2) 5≦TAM≦25

(3) 15≦TAM+TNM≦25

However, the aforementioned TAM and TNM are TAM=Y%+Ti%+Zr%+Hf%+V%+Nb%+Ta%+B%/2, respectively.

TNM=Cr%+Mo%+W%+Mn%+Ni%/3+Cu%/3+Al%+C%+Si%+P%+Zn%+Ga%+Ge%+Sn%.

Further, according to the aspect of the invention, the above alloy preferably satisfies the following formula (4):

(4) 0.25 ≦ (Nb% + Ta%) / (TAM + TNM) ≦ 1.00.

According to another aspect of the invention, the above alloy preferably satisfies the following formula (5) and/or (6):

(5)0≦Ti%+Zr%+Hf%+B%/2≦5

(6) 0 < Cu% + Sn% + Zn% + Ga% ≦ 10.

According to another aspect of the invention, the above alloy is preferably composed only of: Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, One or more selected from the group consisting of Ni, Cu, Al, B, C, Si, P, Zn, Ga, Ge, and Sn, and the remainder of Co and Fe, and satisfying the following formula in at% (1)~(3):

(1) 0.50≦Fe%/(Fe%+Co%)≦0.90

(2) 5≦TAM≦25

(3) 15≦TAM+TNM≦25

However, the aforementioned TAM and TNM are TAM=Y%+Ti%+Zr%+Hf%+V%+Nb%+Ta%+B%/2, respectively.

TNM=Cr%+Mo%+W%+Mn%+Ni%/3+Cu%/3+Al%+C%+Si%+P%+Zn%+Ga%+Ge%+Sn%.

According to another aspect of the invention, the saturation magnetic flux density of the above alloy preferably exceeds 0.5 T and does not reach 1.1 T.

According to another aspect of the present invention, there is provided a sputtering target which is formed from an alloy of any of the above states.

As described above, the present invention provides a soft magnetic alloy for a magnetic recording medium and a sputtering target for forming the alloy thin film, the soft magnetic alloy having a soft magnetic amorphous alloy having a low saturation magnetic flux density, and In the antiferromagnetically bonded multilayer film in which a non-magnetic thin film such as Ru is interposed between the alloy films, the alloy having a large area for the external magnetic field is not well oscillated, and the magnetization of the external magnetic field of the non-inductive region or higher is preferably started. Thus, in the soft magnetic alloys of the present application, the idea of actively targeting low Bs has never been seen before. This idea is the most characteristic idea of the invention.

Figure 1 is a schematic view of a magnetization curve of a multilayer film.

Figure 2 is a graph showing the Hbias correlation of Bs of a multilayer film with a multilayer film.

Figure 3 is a graph showing the effect of Ra of a single layer film and Hbias of a multilayer film on the sharpness of magnetization initiation after Hbias.

The invention is specifically described below. Unless otherwise specified, "%" in this specification means at%.

The present invention relates to an alloy for a soft magnetic film layer in a magnetic recording medium, the alloy comprising: Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Ni, Cu, One or more selected from the group consisting of Al, B, C, Si, P, Zn, Ga, Ge, and Sn, and the remainder of Co and Fe are preferably substantially composed only of the elements (consisting essentially Of), better consisting only of these elements. As described above, the alloy in the present invention is expressed by at% and satisfies the following formulas (1) to (3):

(1) 0.50≦Fe%/(Fe%+Co%)≦0.90

(2) 5≦TAM≦25

(3) 15≦TAM+TNM≦25

However, the aforementioned TAM and TNM are TAM=Y%+Ti%+Zr%+Hf%+V%+Nb%+Ta%+B%/2, respectively.

TNM=Cr%+Mo%+W%+Mn%+Ni%/3+Cu%/3+Al%+C%+ Si%+P%+Zn%+Ga%+Ge%+Sn%.

Hereinafter, the present invention will be described in detail.

First, in order to investigate the effect of soft magnetic film composition on Hbias, after evaluating Hbias for soft magnetic films of various compositions, it is understood that the size of Hbias varies not only with the size of Bs, but also with Fe%/(Fe%+Co%). And change. That is, when it is found that more than 0.5T and less than 1.1T, even a soft magnetic film having a lower Bs than the conventional example can be in a specific Fe%/(Fe%+Co%) range. Get high Hbias.

Next, after reviewing the magnetization initiation by the applied magnetic field of Hbias or more, it is known that there are many Nb and Ta among the additive elements other than Fe and Co, and there are few Ti, Zr, Hf, and B, and Cu, Sn, and When Zn or Ga is added in a small amount, it has an effect. Therefore, it is understood that the elements have a high Hbias by setting the elements to a specific addition amount, and additionally, a display magnetization start effect is additionally obtained.

Based on such new insights, it is completely different from the required characteristics of alloys for soft magnetic films used in perpendicular magnetic recording media in the past, and it has been found that Hs has a lower Bs and also shows a large Hbias, and thus has a high Hbias and a higher Hbias. The magnetization-induced soft magnetic alloy caused by the application of the magnetic field can have high resistance to external noise magnetic fields and high recording density due to suppression of unclear writing in the past, thus completing the present invention. . Hereinafter, the reasons for limitation of the alloy of the present invention will be described.

(a) About 0.50≦Fe%/(Fe%+Co%)≦0.90

Fe and Co are used to have a minimum of the magnetization stability of the recording film. The element of the desired magnetization, the behavior of Bs and Fe%/(Fe%+Co%) is shown as a so-called Slater-Pauling Curve. Furthermore, in the lower Bs, Fe%/(Fe%+Co%) is also used as an important factor with high Hbias. When Fe%/(Fe%+Co%) is less than 0.50, Hbias becomes smaller than a soft magnetic film having the same degree of Bs and 0.50 or more. Although the detailed reason for this phenomenon is not clear, it is considered that the AFC bond participates in the interlayer interaction due to the 3d electron orbital in the magnetic element together with the Bs of the soft magnetic film, and it is presumed that this will vary with the ratio of Fe to Co. Have an impact. Further, when Fe%/(Fe%+Co%) exceeds 0.90, Bs is remarkably lowered, and sufficient Hbias cannot be obtained. Further, the preferred Fe%/(Fe%+Co%) range is 0.55 or more and 0.85 or less, more preferably 0.60 or more and 0.80 or less.

(b) About 5≦TAM≦25 and 15≦TAM+TNM≦25

The effects on elements other than Fe and Co are as follows. Ti, Zr, Hf, and B are elements that cause amorphization promotion and Bs reduction, and are also elements that greatly inactivate the magnetization initiation. Further, in B, since B has a effect of lowering Bs and increasing amorphousness by about 1/2 compared with Ti, Zr, and Hf, it is treated at B%/2 in TAM. However, in the sputtering target, since B generates a particularly hard compound (for example, boride), the processing speed at the time of machining must be lowered. Therefore, B is added as a composite element in the TAM. Add better. From this point, (B/2)/TAM is preferably 0.8 or less, more preferably 0.5 or less.

Y, V, Cr, Mo, W also cause Bs to decrease while making Magnetization initiates a slightly passivated element. Moreover, Y and V also contribute to the promotion of amorphization. Nb and Ta are important elements which contribute to the effect of making the magnetization start sensitive while causing the increase in the amorphization and the decrease in the Bs. Mn, Al, Si, Ge, and P are also elements which cause a decrease in Bs and a slight passivation of the magnetization initiation. Ni and Cu are elements having a small decrease in Bs, and when Cu is added in a small amount, it has an effect of making the magnetization start sensitive, but when a large amount is added, the magnetization start-up is slightly lowered.

Further, compared with the elements classified in other TAM or TNM, Ni and Cu have a reduction in Bs of about 1/3, so in TNM, Ni%/3 and Cu%/3 can be treated. Ga, Sn, and Zn are used to lower the Bs, and at the same time, a small amount of addition has the effect of making the magnetization start sensitive, but when added in a large amount, the magnetization initiates a slightly passivated element. Therefore, all of the elements have an effect of lowering Bs, and are also elements which affect the improvement of the amorphous property or the start of magnetization. The alloy of the present invention is obtained by optimizing the amount of addition.

When TAM is less than 5, sufficient amorphousness cannot be obtained. When it exceeds 25, Bs becomes low and sufficient Hbias cannot be obtained. Therefore, the TAM is 5 or more and 25 or less, preferably 7 or more and 23 or less, more preferably 9 or more, and less than 20. Further, since Nb and Ta are brittle intermetallic compounds with Fe or Co in the sputtering target, it is necessary to add only Nb or/and Ta as TAM, so that cracking does not occur during machining. Or the way the defect reduces the processing speed. When this point is considered, in the case where only Nb or/and Ta is added as the TAM, the TAM is preferably set to less than 20.

TAM+TNM is less than 15 when Hs is increased due to Bs becoming larger Plus, but the magnetization starts to become dull. When TAM+TNM exceeds 25, Bs decreases and Hbias becomes smaller. Therefore, the TAM+TNM is 15 or more and 25 or less, preferably 17 or more and 23 or less, more preferably 18 or more and 21 or less.

(c) About 0.25 ≦ (Nb% + Ta%) / (TAM + TNM) ≦ 1.00

As described above, Nb and Ta are important elements having an additional effect of sharpening the magnetization in the present alloy, but when (Nb%+Ta%)/(TAM+TNM) is less than 0.25, this effect cannot be obtained. Further, since the amount of addition of Nb and Ta is included in the TAM, the upper limit of (Nb%+Ta%)/(TAM+TNM) is inevitably 1.00. Therefore, (Nb%+Ta%)/(TAM+TNM) is 0.25 or more and 1.00 or less, preferably 0.40 or more, less than 1.00, more preferably 0.60 or more, and less than 1.00.

(d) About 0≦Ti%+Zr%+Hf%+B%/2≦5 and 0<Cu%+Sn%+Zn%+Ga%≦10

As described above, in the present alloy, Ti, Zr, Hf, and B are elements which greatly inactivate the magnetization start. Therefore, by strictly defining the upper limit of the total amount of the alloy, it is possible to obtain a more sensitive magnetization start by an additional effect. When Ti%+Zr%+Hf%+B%/2 exceeds 5, the effect of making the magnetization start sensitive is not obtained. Therefore, Ti%+Zr%+Hf%+B%/2 is 0 or more and 5 or less, preferably 3 or less, more preferably 0.

As described above, in the present alloy, Cu, Sn, Zn, and Ga are elements which have an additional effect of sharpening the magnetization when added in a small amount. A more sensitive magnetization start is obtained by actively adding in a small amount range. Therefore, when Cu%+Sn%+Zn%+Ga% exceeds 10, this effect cannot be obtained. Therefore, Cu%+Sn%+Zn%+Ga% is more than 0 and 10 or less, preferably 1 or more and 8 or less, more preferably 2 or more and 6 or less. Further, in both of the two equations, the effect of making the magnetization activation sharp can be obtained only if either one is satisfied.

The detailed reason for the influence of the magnetization start other than the influence of various elements described above on Bs is not clear, but it is presumed as follows. The magnetization initiation is sensitive to the applied magnetic field above Hbias, and the surface roughness of the sputter film of the soft magnetic alloy is observed to have an influence. The phenomenon of magnetization initiated by an external magnetic field above Hbias is considered to be due to the fact that the AFC bond at the interface between the soft magnetic film and the Ru film cannot withstand a large applied magnetic field, causing magnetization reversal, but the surface of the soft magnetic film is rough, on both films. When there is unevenness at the interface, there is a possibility that a portion where the local magnetization reversal occurs relatively quickly and a portion where the magnetization reversal is caused to be slow is mixed.

As described above, when the magnetization reversal behavior does not coincide depending on the portion, the magnetization start becomes slow as a whole of the film. Therefore, consider whether the correlation between the surface roughness of the sputter film and the acuity of magnetization initiation can be seen. Furthermore, the influence of the additive element on the surface roughness of the sputtered film is presumed to be an influence of the free volume of the amorphous alloy and the excess free volume. These two volumes correspond to the volume of the interatomic gap between the atoms in the amorphous alloy. When the volume is large, the atoms in the alloy are not densely packed. Therefore, it is considered that the surface roughness of the sputtering film is increased in atomic size.

Although suggesting that the two volumes are related to the stability of the amorphous However, in the present invention, Ti, Zr, Hf, and B which greatly inactivate the magnetization start are elements which are particularly stable to amorphous, and a small amount of Cu, Ga, Sn, and Zn which are sensitive to magnetization activation are used. An element of reduced amorphousness. Further, Nb and Ta which are important elements for magnetization activation are compared with Ti, Zr, Hf, and B, and are elements which promote a low amorphous effect.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples.

A soft magnetic alloy powder having the composition shown in Table 1 was produced by a gas atomization method. The molten base material was inductively melted in a reduced pressure Ar at 25 kg, and the molten alloy was allowed to flow out from a nozzle having a diameter of 8 mm, and immediately sprayed with a high-pressure Ar gas to be atomized. This powder was classified into 500 μm or less, and used as a raw material powder for HIP molding (hot pressure pressing). A billet for HIP forming is produced by filling a raw material powder into a carbon steel can having a diameter of 200 mm and a length of 10 mm, and then degassing it by vacuum and sealing it. The powder-filled steel ring blank was subjected to HIP molding under the conditions of a temperature of 1,100 ° C, a pressure of 120 MPa, and a holding temperature of 2 hours. Subsequently, a soft magnetic alloy sputtering target having a diameter of 95 mm and a thickness of 2 mm was produced from the molded body. A soft magnetic film was produced using the sputtering target made of the soft magnetic alloy. Further, in the production of the Ru film, a commercially available sputtering target made of Ru metal was used.

The chamber was evacuated to a pressure of 1 × 10 ^-4 Pa or less, and an Ar gas of 0.6 Pa purity and 99.99% was thrown and sputtered. First, a 20 nm soft magnetic alloy film (lower soft magnetic layer) was formed on a cleaned glass substrate, and a 0.8 nm Ru film was formed thereon, and a 20 nm soft magnetic alloy was formed thereon as well as the above film. A film (upper soft magnetic layer) was used to produce a multilayer film. Further, in the entire examples and the comparative examples, the same alloy was used for the upper soft magnetic film of the multilayer film. Further, a single layer film of only the soft magnetic film under film formation was also used as the Bs of the soft magnetic film, the crystal structure, and the surface roughness evaluation.

The monolayer film thus produced was used as a sample, and VSM (sample vibration type magnetic flux meter) was used for Bs, X-ray diffraction was used for crystal structure, and arithmetic mean roughness Ra (surface roughness) was evaluated by AFM (atomic force microscope). Regarding the crystal structure, ○ is amorphous, and Δ is a part of microcrystals in the amorphous, and × is crystallization. Furthermore, the sensitivity of Hbias and magnetization initiation was evaluated from the multilayer film. These results are shown in Table 2.

Figure 1 is a schematic view of a magnetization curve of a multilayer film. As shown in the figure, Hbias is evaluated by the applied magnetic field when the magnetization of the multilayer film is initiated, and the sensitivity of the magnetization initiation is evaluated by the ratio of the applied magnetic field (Hsat) of the multilayer film to Hbias, that is, Hsat/Hbias. . Fig. 1(a) shows an example in which Hbias is large and magnetization is sharp, and Fig. 1(b) shows an example in which Hbias is small and magnetization is relatively blunt. That is, the closer the value is to 1, the more sensitive the magnetization start is. When the value is less than 1.2, it is ◎, and it is 1.2 or more. When it is less than 1.4, it is ○, 1.4 or more, when it is less than 1.8, it is △, and when it is 1.8 or more, it is represented by ×.

[Table 1]

[Table 2]

As shown in Tables 1 and 2, numbers 1 to 28 are examples of the invention, and numbers 29 to 39 are comparative examples.

2 is a graph obtained by plotting Hbias of a multilayer film as a vertical axis and Bs of a single layer film as a horizontal axis in the results of Table 2. As shown by the ellipse of the solid line in the figure, in order to obtain high Hbias, high Bs is necessary. Further, the data in the ellipse of the solid line is in the range of Fe%/(Fe%+Co%) in the range of 0.5 to 0.9. On the other hand, in Comparative Example Nos. 29 to 31 in FIG. 2 which is lower than the solid ellipse, since Fe%/(Fe%+Co%) is less than 0.5, Bs having the same data as in the solid ellipse is obtained. At the same time Hbias is limited to lower values. That is, by making Fe%/(Fe%+Co%) 0.50 to 0.90, high Hbias can be obtained even for a relatively low Bs.

On the other hand, in Comparative Example Nos. 32 to 36 in the ellipse of the lower left dotted line in Fig. 2, since Bs is remarkably low, Hbias is also limited to be low. Further, Comparative Example No. 39 is a composition in which Fe%/(Fe%+Co%) is 0.4, and TAM+TNM is small and does not reach 15, which is a high Bs composition which is common in the prior art. This composition is plotted on the right side of the solid ellipse in Figure 2. Compared to the composition of the ellipse in the solid line, it is necessary to obtain a significantly larger Hbia, which is a significantly larger Bs. "The writing is not clear."

Figure 3 is a graph showing the results of Table 2, with the Hbias of the multilayer film as the vertical axis and the Ra of the single layer film as the horizontal axis. The symbol of the graph is the magnetization initiation acuity of the multilayer film with the external magnetic field above Hbias applied. And the change. As is clear from the figure, even in the case of a multilayer film having the same Hbias, when the surface roughness (Ra) of the single layer film is large, the magnetization start is deteriorated.

Next, the data of each comparative example shown in Table 2 will be described. Comparative Examples Nos. 29 to 31 have low Fe%/(Fe%+Co%) values, and although they have a Bs of 0.80 to 0.86 T, high Hbias cannot be obtained. In Comparative Examples Nos. 32 and 33, since Fe%/(Fe%+Co%) was too high, Comparative Examples Nos. 34 and 35 were higher in TAM+TNM, and Comparative Example No. 36 was higher in TAM and TAM+TNM, so Bs was remarkable. Lower, unable to get high Hbias.

In Comparative Example No. 37, since TAM+TNM is low, although Bs is high and high Hbias is obtained, the magnetization start for the external magnetic field exceeding Hbias is blunt. Comparative Example No. 38 had a low TAM and was crystalline, and the irregularities on the surface of the single layer film caused by the crystal grains caused Ra to be high, and the magnetization for the external magnetic field exceeding Hbias was blunt. Comparative Example No. 39 because the Fe%/(Fe%+Co%) value is low, TAM+TNM is low, and although it has a significantly high Bs, only Hbias can be obtained to the same extent as the embodiment, so that the composition of Bs is significantly higher. Caused the so-called "writing is not clear."

Comparing with these, it can be seen that the embodiment numbers 1 to 28 are all within the scope of the present invention, so that the Bs which is less than 1.1 T is lower than the prior art, and has high Hbias, and thus is sharply sensitive to the applied magnetic field exceeding Hbias. Magnetization starts. According to this kind of composition, it is possible to have resistance to high external noise magnetic fields and to suppress unclear writing due to excessive Bs. Further, in the examples Nos. 8 to 12 (Nb% + Ta%) / (TAM + TNM) are in the range of 0.5 to 1.0, the roughness of the single layer film (Ra) can be obtained from the embodiment numbers 1 to 7. Small and magnetized to activate the sharp additional effect.

Further, Ti%+Zr%+Hf%+B%/2 of Example Nos. 13 to 28 are 5 or less and/or Cu%+Sn%+Zn%-+Ga% exceeds 0 and 1 or less. Therefore, from the embodiment numbers 1 to 7, the additional effect of the roughness (Ra) of the single layer film and the sharpness of the magnetization start can be obtained. Further, Example No. 23 has the highest Hbias in the examples, and Ti%+Zr%+Hf%+B%/2 is 5 or less. Therefore, it is understood that magnetization starting is equivalent to that of the embodiment numbers 1 to 7.

As described above, the soft magnetic alloy of the present invention has a soft magnetic alloy which has a minimum Bs for magnetizing the recording film and has a high Hbias even at a lower Bs, and has an additional effect of a sharp magnetization start. An alloy for soft magnetic film layers and a sputtering target that can provide both high resistance to external magnetic fields and high recording density due to "unclear writing" and low saturation magnetic flux density Very good effect.

Claims (6)

An alloy which is an alloy for a soft magnetic film layer in a magnetic recording medium, wherein the alloy comprises Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Ni, Cu, Al, One or more selected from the group consisting of B, C, Si, P, Zn, Ga, Ge, and Sn, and the remainder of Co and Fe, and satisfying the following formula (1) to (3) in at% ): (1) 0.50 ≦ Fe% / (Fe% + Co%) ≦ 0.90 (2) 5 ≦ TAM ≦ 25 (3) 15 ≦ TAM + TNM ≦ 25 However, the aforementioned TAM and TNM are TAM = Y% + Ti%+Zr%+Hf%+V%+Nb%+Ta%+B%/2 TNM=Cr%+Mo%+W%+Mn%+Ni%/3+Cu%/3+Al%+C %+Si%+P%+Zn%+Ga%+Ge%+Sn%. The alloy of claim 1, which satisfies the following formula (4): (4) 0.25 ≦ (Nb% + Ta%) / (TAM + TNM) ≦ 1.00. The alloy of claim 1 or 2, which satisfies the following formula (5) and/or (6) (5) 0 ≦ Ti% + Zr% + Hf% + B% / 2 ≦ 5 (6) 0 < Cu% +Sn%+Zn%+Ga%≦10. The alloy of claim 1 or 2, wherein the alloy is only composed of: Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Ni, Cu, Al, B, C, Si One or more selected from the group consisting of P, Zn, Ga, Ge, and Sn, and the remainder of Co and Fe, And satisfying the following formula (1) to (3) in at%: (1) 0.50 ≦ Fe% / (Fe% + Co%) ≦ 0.90 (2) 5 ≦ TAM ≦ 25 (3) 15 ≦ TAM + TNM ≦25, except for the above TAM and TNM are TAM=Y%+Ti%+Zr%+Hf%+V%+Nb%+Ta%+B%/2 TNM=Cr%+Mo%+W%+Mn% +Ni%/3+Cu%/3+Al%+C%+Si%+P%+Zn%+Ga%+Ge%+Sn%. An alloy according to claim 1 or 2, wherein the saturation magnetic flux density exceeds 0.5 T and does not reach 1.1 T. A sputtering target for use in the manufacture of a soft magnetic film composed of the alloy of any one of claims 1 to 5.