JP2569828B2 - Magnetic alloys for magnetic devices - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic alloy for a magnetic device which is particularly suitable for a magnetic head for high density magnetic recording.

(Prior Art) In recent years, the need for higher density and wider bandwidth of magnetic recording has been increased, and by using a magnetic material having a high coercive force for a magnetic recording medium and narrowing a recording track width, high density recording / reproduction has been achieved. Has been realized.

As a magnetic head material for recording and reproducing data on and from a magnetic recording medium having a high coercive force (Hc), a magnetic alloy having a high saturation magnetic flux density (Bs) is required. There has been proposed a magnetic head using a part of or the entire core.

However, when the coercive force of the magnetic recording medium is further increased, and when the coercive force becomes 2000 Oe or more, it becomes difficult to perform good magnetic recording and reproduction with a magnetic head using a sendust alloy or an amorphous alloy.

In addition, a perpendicular magnetization recording method in which recording is performed by magnetizing the magnetic recording medium not in the longitudinal direction but in the thickness direction has been proposed. However, in order to perform this perpendicular magnetization recording method satisfactorily, the tip of the main pole of the magnetic head is required. The thickness of the portion must be 0.5 μm or less, and a magnetic head having a high saturation magnetic flux density is also required for recording on a magnetic recording medium having a relatively low coercive force.

As a magnetic head alloy having a higher saturation magnetic flux density than a sendust alloy, an amorphous alloy, or the like, a magnetic alloy containing iron as a main component such as iron nitride or an Fe-Si alloy is known.

(Problems to be Solved by the Invention) However, conventionally known magnetic alloys having a high saturation magnetic flux density have a large coercive force and are inadequate as materials for magnetic heads as they are. A magnetic head having a multilayer structure using a magnetic material having a small coercive force as an interlayer film has been proposed.

However, there is a problem that it takes a lot of man-hours and costs to form a multilayer structure, and it is difficult to maintain reliability. In particular, in order to achieve a film thickness of several μm or more, 100
It was necessary to have a multilayer structure having more than two layers, and the range of use was limited. In order to solve this problem, the present inventors have
It has been proposed that a single layer of high Bs and low Hc magnetic alloy can be obtained by using a -NO alloy, but there is a problem that it is not suitable for a glass molding process from the viewpoint of thermal stability.

Accordingly, it is an object of the present invention to provide a magnetic alloy for a magnetic device having a high saturation magnetic flux density without having a multilayer structure, and having a small coercive force and excellent thermal stability.

(Means for Solving the Problems) The present invention has been made in view of the above problems Fe _v N _w O
_The atomic% represented by the composition formula _x Si _y , represented by v, w, x, y, is 1 ≦ w ≦ 20 0.1 ≦ x ≦ 20 0.5 ≦ y ≦ 6 v + w + x + y = 100 Alloy, or represented by the composition formula of F _v N _w O _x Si _y Ru _z , and v, w, x,
The atomic percentages represented by y and z provide magnetic alloys for magnetic devices having a relationship of 1 ≦ w ≦ 20 0.1 ≦ x ≦ 20 0.5 ≦ y ≦ 6 0.3 ≦ z ≦ 3 v + w + x + y + z = 100.

(Example) FIG. 1 shows an example of an apparatus for producing a magnetic alloy for a magnetic device according to the present invention.

The pair of targets 5,5 are iron (Fe) and silicon (Si),
It is an alloy target of an additive element such as ruthenium (Ru) or a composite target in which chip-shaped Si or Ru is fitted into a concave portion of a pure iron target provided with an appropriate concave portion.
The targets 5 and 5 are supported by a target holder 9. A negative potential is applied to the targets 5 and the target holder 9 from a DC power supply 13, and a shield 4 is attached around the target holder 9. .

Further, inside the target holder 9, magnets 6,6 for focusing the plasma 14 between the targets 5,5 are inserted, and cooling water 8 flows into the target holder 9 to prevent the surface of the target 5 from being heated. I have.

Two target holders 9 are provided on the left and right sides of the grounded vacuum chamber 15 insulated by the insulator 7.

Oxygen (O ₂ ), nitrogen (N ₂ ), and argon (Ar) are introduced from the upper part of the vacuum chamber 15 at a predetermined flow rate by flow meters 1 to 3, respectively.

Argon is used to adjust the amounts of nitrogen and oxygen in the magnetic alloy film formed simultaneously with sputtering of the target 5.

The substrate 11 is placed on the substrate holder 12 below the vacuum chamber 15, and a shutter 10 for preventing impurities is provided on the substrate 11.
Covers 11.

In such a sputtering apparatus, when the plasma 14 is generated between the targets 5 supported by the left and right target holders 9 by the DC power supply 13, the target 5
Is a negative potential, so that argon ions (Ar ⁺ ) in the plasma 14 collide with the target 5, and iron atoms of the target 5 and atoms such as Si or Ru jump out. And
The iron atoms jumping out of the target 5 are combined with the oxygen and nitrogen atoms or molecules in the plasma and grow on the substrate 11.

Note that for a few minutes after the start of sputtering, the shutter 10 is closed to cover the substrate 11 so that impurities on the surface of the target 5 do not adhere to the substrate 11, and then the shutter 10 is opened.

Then, oxygen at a flow rate meter 1-3, nitrogen, by adjusting the introduction amount of argon, it is possible to obtain a desired containing oxygen and nitrogen Fe _v N _w O _x Si _y a composition formula of the alloy.

Thus Fe _v N _w O _x Si _y a composition formula of the alloy of nitrogen obtained, oxygen and saturation magnetic flux density after performing the heat treatment at 300 ° C. in a content of the additive element and rotating magnetic field, such as Ru ( The relationship between Bs) and coercive force (Hc) is shown in the table.

This table is a table showing the relationship between the contents of oxygen, nitrogen, Ru, and Si, the saturation magnetic flux density (Bs), and the coercive force (Hc). The contents are ESCA (X-ray photoelectron spectroscopy), EPMA
(X-ray microanalyzer method) It is expressed in atomic% by quantitative analysis. In the table, an error of ± 20% is expected. The coercive force is a value when heat treatment is performed in a vacuum, and the heat treatment temperature is 300 ° C. In the table, Sample No. 1 is the result when iron contains only nitrogen, Sample No. 2 is the result when iron contains oxygen and nitrogen, and Sample No. 3 is the result when iron contains only Si. The result. Sample numbers 5 to 11 show the magnetic alloys of the present invention.

At the heat treatment temperature of the Fe-Si-O alloy of sample number 4 below 300 ℃
Although Hc is low, when it exceeds 300 ° C., Hc sharply increases and is not suitable for a glass mold which is a general processing method of a magnetic head.
Further, the Fe-Si alloy of Sample No. 3 has a large Hc of 8.0 Oe, and the Fe-N alloy of Sample No. 1 has a relatively small Hc but larger than 1 Oe, and particularly has insufficient heat resistance. On the other hand, as represented by sample No. 5 shown in FIG. 2, the magnetic alloy of the present invention has the heat resistance capable of glass molding as described above such that Hc is 0.1 Oe at a heat treatment temperature of 500 ° C. Satisfies the required low Hc at the same time, and Bs shows a high value of 19KG.

Here, when the oxygen content is less than 0.1 atomic%, a remarkable effect of oxygen is not seen, and Hc hardly decreases.
On the other hand, if the oxygen content exceeds 20 atomic%, the soft magnetic properties are significantly deteriorated, and Bs decreases and Hc increases. Therefore,
Oxygen content is 0.1 to 20 atomic%, more preferably 0.1 to
When the content is 10 atomic%, a magnetic alloy having a high Bs and a small Hc can be obtained. When the nitrogen content is less than 1 atomic%, no remarkable improvement in magnetic properties is not seen, and when it exceeds 20 atomic%, Bs decreases and Hc increases, and particularly, Bs achieves the high Bs which is the object of the present invention. become unable. Therefore, when the nitrogen content is 1 to 20 at%, more preferably 1 to 10 at%, Bs is high and Hc is high.
Is obtained.

FIG. 2 shows a change in coercive force (Hc) depending on the heat treatment temperature of the magnetic alloy of the present invention and the conventional iron nitride alloy.

From FIG. 2, it can be seen that the magnetic alloy of the present invention has a small Hc and is excellent in thermal stability. Here, when the Si content is less than 0.5 atomic%, no remarkable effect on lowering Hc and improving thermal stability is not seen, and when it exceeds 6 atomic%, high Bs
Further, a magnetic alloy having a low Hc cannot be obtained.

Therefore, in an alloy having a composition represented by the formula of F _v N _w O _x Si, a magnetic alloy for a magnetic device which exhibits excellent soft magnetic properties when x, w, x, y is the following atomic% is obtained. .

 That is, the relationship 1 ≦ w ≦ 20 0.1 ≦ x ≦ 20 0.5 ≦ y ≦ 6 v + w + x + y = 100 may be satisfied.

FIG. 3 shows that Ru contributes to the improvement of corrosion resistance. After immersing a sample in 2 Wt% salt water, take out the sample and place the sample in a constant temperature and humidity of 60 ° C.-90%. I left it.
In the figure, the abscissa represents the standing time, and the ordinate represents the value of Bs [Bs (t)] after standing against Bs [Bs (0)] before immersion in salt water.

If the Ru content is less than 0.3 atomic%, a remarkable effect of Ru is not seen, and if it exceeds 3 atomic%, high Bs and low Hc cannot be achieved. Therefore, the content of Ru is preferably 0.3 atomic% to 3 atomic%.

Furthermore, mainly for the purpose of improving corrosion resistance and wear resistance, carbon, aluminum, titanium, vanadium, chromium, cohard, nickel, copper, gallium, germanium, yttrium, zirconium, molybdenum, silver, indium, tin, antimony, 3 at% of at least one element from the group consisting of hafnium, tungsten, platinum, gold, thallium, lead and palladium
The following can be contained.

Therefore, Fe _v in N _w O _x Si _y Ru _z becomes alloy having a composition represented by the formula, v, w, x, y , z is, 1 ≦ w ≦ 20 0.1 ≦ x ≦ 20 0.5 ≦ y ≦ 6 0.3 ≦ When z ≦ 3 v + w + x + y + z = 100 atomic%, a magnetic alloy for a magnetic device exhibiting excellent soft magnetic properties and having excellent corrosion resistance can be obtained.

Further, by alternately laminating the magnetic alloy of the present invention and another soft magnetic material (such as sendust) to form a multilayer structure, a further reduction in coercive force can be expected. A magnetic alloy for a magnetic device having excellent magnetic properties even with a layer structure can be obtained.

(Effects of the Invention) The present invention provides a magnetic head having a high saturation magnetic flux density, a low coercive force, and excellent thermal stability and corrosion resistance by using a magnetic alloy having the above composition formula. Magnetic alloys for magnetic devices such as Therefore, when the magnetic alloy for a magnetic device of the present invention is used, good recording and reproduction on a high coercivity magnetic medium can be performed, and a high-performance thin-film magnetic head can be manufactured. As a result, high-density magnetic recording and reproduction can be performed. There are features that can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic view of a sputtering apparatus which is an example of an apparatus for producing a magnetic alloy for a magnetic device according to the present invention, and FIG. FIG. 3 is a diagram showing characteristics of corrosion resistance by Ru in the alloy of the present invention.

Claims (2)

(57) [Claims] 1. The atomic percentage represented by the composition formula FevNwOxSiy, represented by v, w, x, y, is as follows: 1 ≦ w ≦ 200, 1 ≦ X ≦ 200, 5 ≦ y ≦ 6 V + W + X + Y = 100 Related magnetic alloys for magnetic devices. 2. The atomic% represented by the composition formula FevNwOxSiyRuz, represented by v, w, x, y, Z, is 1 ≦ w ≦ 200, 1 ≦ x ≦ 200, 5 ≦ y ≦ 60, 3 ≦ Z ≦ 3 V + W + X + Y + Z = 100 A magnetic alloy for a magnetic device having the following relationship: