JPH0770395B2 - Magnetoresistive alloy film - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive alloy film for MR (magnetoresistive) heads.

Conventional technology Magneto-resistive effect expressed by the following formula as a material for MR headIt is desirable to use a soft magnetic material that has a large magnetic field and a small coercive force Hc.
Yes. Where ρ_⊥Is the resistance when the current is perpendicular to the magnetization direction, ρ
Is the resistance when parallel, ρ_oIs the demagnetized resistance
It From this point of view, it exhibits soft magnetism and Δρ / ρ_oIs about
2% permalloy (Ni₈₀Fe₂₀) Alloy is currently mainly MR
It is used in the head.

Problems to be Solved by the Invention [Delta] [rho] / [rho] _o of permalloy is not practically sufficient, and a material having higher characteristics is desired. It has been found that the value of Δρ / ρ _o 6% can be obtained with the Ni ₈₀ Fe ₂₀ alloy if only focusing on the magnetoresistive effect, but this alloy does not show soft magnetism with sufficiently small Hc, so it is not so much. It was not put to practical use.

Means for Solving Problems Ni _100-X Co _X (10 ≦ × ≦ 40 (at%) alloy film and M _100-UV T _U X _V (0 ≦ u ≦ 25,0 ≦ V ≦ Amorphous alloy film represented by 30 (at%) (where M is Fe, Co, Ni, Mn, C
One or more elements selected from r, Mo, W, T is Ti, Z
1 or 2 or more elements selected from r, Hf, Nb, Ta, Ru, Re, X is 1 or 2 or more elements selected from P, C, B, Si, Ge, Al Represent. ) And are alternately laminated to form a film.

The characteristic of the working Ni-Co alloy film, which has a large Δρ / ρ _o , and the soft magnetism of the amorphous alloy film, are effectively exhibited.
/ Ρ _o exceeds Permalloy, and an alloy film exhibiting soft magnetism is obtained.

Example In the present invention, the value of Δρ / ρ _o is large, but Hc is large and it is not practical. The Ni _100-X Co _X alloy system of 10 ≦ X ≦ 40 and soft magnetism and relatively high electric resistance. An amorphous alloy film is alternately laminated to obtain a magnetoresistive material which exhibits soft magnetism as a whole and has Δρ / ρ _o higher than that of a conventional permalloy alloy. Of course, by simply stacking the layers, the magnetization curve as a whole becomes smaller than that of the amorphous alloy part with a small Hc and Ni-Co with a relatively large Hc.
A two-step curve piled up with the alloy part is shown, but as the thickness of one layer of each alloy film is made thinner, as a whole
It has been found that Hc has a small soft magnetism and does not exhibit the above-described two-step magnetization curve. At this time, it is generally desirable that the thickness of one layer of each alloy film is 1000 Å or less. If the magnetoresistive effect is large, 10 ≦ X ≦ 40
Ni _100-X Co _X alloy system, not an amorphous alloy, so △
In order to obtain a sufficiently large value for ρ / ρ _o, it is desirable that the thickness of the former layer is at least thicker than the thickness of the latter layer. Furthermore, if a high-temperature heating process is required in the MR head manufacturing process, etc., Ag, Cu, Mg that are difficult to form a solid solution with both alloys to prevent diffusion between both alloy layers.
It is effective to provide a thin interlayer diffusion preventive layer made of, for example,
It should be noted that it is not necessary to provide such a layer when using at room temperature because the heating step is unnecessary.

Further, as an amorphous alloy exhibiting soft magnetism, one having a composition represented by the following formula is known.

M _100-UV T _U X _V , 0≤u≤25,0≤V≤30 (atomic%) (2) However, M is one kind selected from Fe, Cu, Ni, Mn, Cr, Mo, W Or two or more elements, T is one or more elements selected from Ti, Zr, Hf, Nb, Ta, Ru, Re, X is selected from P, C, B, Si, Ge, Al It is one or more elements. In formula (2), the alloy system of M _100-UV X _V with u = 0 is called a metal-metalloid system, and representative ones are Fe-Si-B and Co-Si-B.
In equation (2), the alloy system of M _100-U T _U with v = 0 is called a metal-metal system, and a typical one is Co-Nb-
Amorphous soft magnetic alloys such as Co--Nb--B are known as intermediate ones of both systems where Zr exists and u ≠ 0 and V ≠ 0 in the equation (2). The following amorphous alloys such as Gd-Co and Tb-Fe do not exhibit soft magnetism and are not suitable for lamination with the above NiCo alloy.

As described above, the amorphous alloy represented by the formula (2) and 10 ≦ X
By stacking ≦ 40 Ni _100-X Co _X alloy, the desired Δρ
Although it has been found that an alloy having a large / ρ _o and exhibiting soft magnetism can be obtained, the effects of the present invention will be described below with reference to specific examples.

<Example 1> Ni _100-X Co _X (X = 10, 20, 40) and Co ₈₅ as targets
A binary sputtering system for forming various laminated films of Ni—Co alloy and amorphous alloy by using six kinds of Nb ₁₀ Zr ₅ Co ₇₀ Fe ₅ Si _12.5 B _12.5 and Co ₆₈ Fe ₂ Nb ₁₀ B ₂₀ Was used to form on a photosensitive glass substrate, and its magnetic characteristics and Δρ / ρ _o effect were measured. The results are summarized in the table below.

As can be seen from the results shown in the table, Δρ / ρ _o are all 3% or more, which is larger than the conventional Ni ₈₀ Fe ₂₀ alloy film, and when the thickness of one layer is 1000 Å or less, Hc is also small and soft. It can be seen that an alloy film exhibiting magnetism can be obtained.

<Example 2> using a _{Ni 80 Co 20, Co 85 Nb} 10 Zr 5, Ag as a target, various multi-layer film having a repeating period of the Ni-Co / Ag / Co- Nb-Zr / Ag by ternary sputtering apparatus Was formed on a photosensitive glass substrate and annealed with the sample of No. 6 of Example 1 at 400 ° C. to examine the thermal stability of the characteristics. The results are shown below.

From the results shown in the table, it can be seen that those having Ag between the layers have excellent thermal stability. If the Ag layer becomes too thick,
It can be seen that Hc is slightly increased and Δρ / ρ _o is slightly decreased, which is not desirable. Moreover, even if Cu and Mg were used, the same effect as Ag was obtained.

Effect of the Invention According to the present invention, a soft magnetic alloy film having a large Δρ / ρ _o effect can be realized.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C23C 14/14 G 9271-4K

Claims (3)

[Claims] 1. An alloy film Ni _100-X Co _X (10 ≦ × ≦ 40 (at%)) represented by the following formula and an amorphous alloy film M _100-UV T _U X _V represented by the following formula: (0 ≦ u ≦ 25, 0 ≦ V ≦ 30 (at%)) (where M is one or more elements selected from Fe, Co, Ni, Mn, Cr, Mo, W, T is Ti, One or more elements selected from Zr, Hf, Mb, Ta, Ru and Re, and X represents one or more elements selected from P, C, B, Si, Ge and Al. ) And are alternately laminated to form a magnetoresistive alloy film. 2. The thickness of one layer of Ni _100-X Co _X is t ₁ , M _100-UV T _U
The magnetoresistive alloy film according to claim ₁ , wherein t ₁ ≦ 1000Å, t ₂ 1000Å and t ₁ ≧ t ₂ when the thickness of one layer of X _V is t ₂ . 3. C between the Ni _100-X Co _X layer and the M _100-UV T _U X _V layer
The magnetoresistive alloy film according to claim 1, wherein a layer made of any one of u, Ag, and Mg is interposed.