JP2000099935A - Intra-surface magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intra-surface magnetic recording medium having a multilayered structure which is excellent in magnetic characteristics. SOLUTION: This medium is the intra-surface magnetic recording medium formed by forming regular lattices of a body centered cubic system represented by B2 regular lattices of an Ni-al system, etc., as a first ground surface layer on a nonmagnetic substrate side and a nonmagnetic second ground surface layer having an hcp structure represented by a CoCr alloy formed on this first ground surface layer as the ground surface layers on a nonmagnetic substrate and arranging a Co magnetic layer as a magnetic layer thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a longitudinal magnetic recording medium for a magnetic disk drive or the like.

[0002]

2. Description of the Related Art Conventionally, magnetic recording media have been developed so as to enable high-density magnetic recording, and as one of the means, an underlayer has been improved. Recently, IEEE
Trans. Magn. , Vol. 30, 3951 (1
994), IEEE Trans. Magn. , Vo
l. 31, 2728 (1995) and others report that the use of a layer having a B2 ordered structure of Ni and Al as an underlayer makes the film crystal grains fine, and a magnetic recording medium with high coercive force and low noise can be obtained. Have been.

[0003] IEEE Trans. Mag
n. , 33, 5, (1997), the use of a CoCr alloy having a hexagonal close-packed structure for the underlayer improves the crystalline consistency with the Co-based magnetic layer, and provides a high coercive force and low noise magnetic recording medium. Is reported to be obtained.

[0004]

SUMMARY OF THE INVENTION The inventor of the present invention
CoC with Al-based alloy underlayer and hexagonal close-packed structure
Examination of the r-alloy underlayer confirmed that it was good as a magnetic recording medium with high coercive force and low noise. However, with the recent increase in recording density of magnetic disks, means for achieving higher coercive force and lower noise are required. An object of the present invention is to provide a magnetic recording medium that improves the magnetic characteristics of a Co-based magnetic layer and is suitable for high-density recording.

[0005]

Means for Solving the Problems The present inventors have studied to improve the magnetic characteristics of a Co-based magnetic layer by reducing the crystal grain size of the underlayer and increasing the consistency with the magnetic layer. As a result, the first with a body-centered cubic regular lattice on the substrate side
It has been found that the object can be achieved by forming an underlayer, a nonmagnetic second underlayer having an hcp structure in this order, and forming a Co-based magnetic layer on the underlayer.

That is, the present invention relates to an in-plane magnetic recording medium having a magnetic layer formed on a nonmagnetic substrate with an underlayer interposed therebetween, wherein the underlayer has a body-centered cubic rule on the nonmagnetic substrate side. A longitudinal magnetic recording medium, comprising: a first underlayer having a lattice; and a nonmagnetic second underlayer having an hcp structure formed on the first underlayer, wherein the magnetic layer is a Co-based magnetic layer. It is.

In the present invention, a body-centered cubic metal layer mainly composed of Cr can be provided between the first underlayer and the second underlayer.

The first underlayer according to the present invention is preferably a B2-ordered lattice as a body-centered cubic ordered lattice, and more preferably a B2-ordered lattice of a Ni-Al alloy. The second underlayer according to the present invention is preferably a CoCr-based alloy or a Ru-based alloy having an hcp structure.

In the Co-based magnetic layer of the present invention, (Cr, Pt, Pd, Ni, Ti, V,
Ta, W, B), and at least 15 at% in total.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, an important feature of the present invention is that a sublayer having a fine body-centered cubic regular lattice capable of reducing the crystal grain size is used as a first sublayer, The non-magnetic second underlayer having the hcp structure having good coordination with the layer is used to reduce the crystal grain size of the magnetic film and improve the coordination between the magnetic layer and the underlayer. The Co-based magnetic layer in the in-plane magnetic recording medium has an hcp structure, and the c-axis direction, which is the direction of easy magnetization, is oriented in the plane. Usually, when a Co-based magnetic layer is formed, the c-axis direction is easily oriented in the direction perpendicular to the plane. Therefore, the orientation is controlled by epitaxial growth from the underlayer.

According to the present invention, a first underlayer having a fine body-centered cubic ordered lattice is formed, and a second nonmagnetic underlayer having an hcp structure having good consistency with a magnetic layer is formed thereon by epitaxial growth. When the c-axis direction is oriented in the plane, the Co-based magnetic layer thereon is also formed with a fine and well-oriented orientation. In the present invention, the first having a body-centered cubic regular lattice
Good matching between the underlayer and the nonmagnetic second underlayer having the hcp structure is required.

As such a body-centered cubic regular lattice, B2 regular lattice, L2 ₁ regular lattice, DO ₃ regular lattice,
C11b regular lattice and the like. Above all, NiA
The 1-system B2 regular lattice is preferable in consideration of matching. Further, it is also possible to add an additional element for matching the lattice constant and miniaturizing the film crystal grain size. Especially NiAl-based B2
In the regular lattice, B, C,
It is effective to add light elements such as O and N, elements of the IVa group and Va group, and to add elements of the VIa group, VIIa group and platinum group mainly for lattice constant matching. Also,
Two or more of these additional elements can be added.

As a material having a nonmagnetic hcp structure, C
o alloy, Ru alloy, Os alloy, Re alloy, Ti alloy, Z
r alloy and the like. Among them, a CoCr-based alloy and a Ru alloy that have good compatibility with the Co-based magnetic layer are preferable.
Further, it is also possible to add an additional element for matching the lattice constant and miniaturizing the film crystal grain size. In particular, in the case of CoCr-based alloys, B, C, O,
Adding light elements such as N, and elements of the IVa and Va groups;
It is effective to add group a and platinum group elements,
In the case of u-based alloys, mainly for miniaturization of the film crystal grain size,
Addition of light elements such as B, C, O, and N, elements of group IVa and group Va, and group VIa and VII mainly for lattice constant matching.
It is effective to add a platinum group element other than group a and Ru. It is also possible to add two or more of these additional elements.

Here, the non-magnetic hcp structure is as follows.
If the underlayer has magnetic properties, the magnetic properties of the Co-based magnetic layer may be affected by the coupling or the like, for example, the magnetic hysteresis curve may have a two-step or flattened shape. This is because they cannot be pulled out sufficiently. C
Considering magnetic properties such as coercive force for the o-based magnetic layer, Co
(Cr, Pt, Pd, Ni,
A Co-based alloy containing at least one of Ti, V, Ta, W, and B) and a total of 15 at% or more is preferable.

[0015] hcp structure, B2 superlattice shows L2 ₁ ordered lattice, DO ₃ ordered lattice, the crystal structure of the C11b ordered lattice in FIGS 1-5. As an hcp structure, a typical C
o-Cr-Ta-Pt, Co-Cr, Ru, Ru-C
Table 1 shows the lattice constants a and c of r, Ru—Mn, and Ru—Co. NiAl, RuAl as examples of B2 ordered lattice
Table 2 shows the lattice constant a. _Co 2 AlTi Examples of L2 ₁ ordered lattice, Table 2 shows the lattice constant a of _Mn 3 Si as a DO ₃ ordered lattice. It is preferable that the lattice constant c with the Co-based magnetic layer to be matched and the diagonal distance of the body-centered cubic ordered lattice be short. Here, the diagonal distance of the regular lattice of the body-centered cubic system is a × 2 ^0.5 in the B2 regular lattice, and (a / 2) × 2 ^0.5 in the L2 ₁ regular lattice and the DO ₃ regular lattice. .

[0016]

[Table 1]

[0017]

[Table 2]

In the present invention, a body-centered cubic metal layer mainly composed of Cr as shown in FIG. 6 can be arranged between the first underlayer and the second underlayer. The body-centered cubic intermetallic compound phase may have poor compatibility with the metal having the hcp structure, and the epitaxial growth may not be performed well. Since the body-centered cubic metal layer mainly composed of Cr has good compatibility with the metal having the hcp structure, epitaxial growth may be easily performed by inserting the metal layer between the first underlayer and the second underlayer. Table 3 shows the lattice constant a of a typical body-centered cubic metal layer mainly composed of Cr.

[0019]

[Table 3]

Even when a body-centered cubic metal layer mainly composed of Cr is inserted between the first underlayer and the second underlayer, Cr
It is preferable to match the lattice constant a of the body-centered cubic metal layer mainly composed of Further, a body-centered cubic metal layer mainly composed of Cr that can be inserted between the first underlayer and the second underlayer is also made of a light element such as B, C, O, or N mainly for the purpose of reducing the film crystal grain size. , IVa and Va elements, and addition of elements of the VIa, VIIa and platinum groups other than Cr for lattice constant matching are effective. It is also possible to add two or more of these additional elements.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Ni-50 at% Al for the first underlayer,
Ru-50at% Al, Co-25at% Al-25a
A target of t% Ti was prepared. Co-37 at% Cr, Co-37 at% Cr-1 at for the second underlayer
% B, Co-37 at% Cr-2 at% Ti, Co-3
7at% Cr-2at% Nb, Co-37at% Cr-
2 at% W, Co-37 at% Cr-5 at% Ru, R
u, Ru-40 at% Cr, Ru-50 at% Mn, R
u-50at% Co, Ru-50at% -1at% B,
Ru-50at% Co-2at% Zr, Ru-50at
% Co-2 at% Ta and Ru-50 at% Co-2
A target of at% Mo was prepared.

Pure Cr, Cr-10 at% Ti and Cr-10 at for a body-centered cubic metal layer mainly composed of Cr
A% Mo target was prepared. A Co-18 at% Cr-5 at% Ta-4 at% Pt target was prepared for a Co-based magnetic layer.

In the combinations shown in Tables 4 to 7, under the conditions of an Ar pressure of 0.66 Pa and a DC power of 500 W, a target for the first underlayer was formed on an Ni-P plated Al substrate.
0 nm is sputtered, and a second target is formed on each substrate under the conditions of an Ar pressure of 0.66 Pa and a DC power of 500 W.
0 nm was sputtered, and a Co-based magnetic layer target was further sputtered to 40 nm to form a magnetic layer. When providing a body-centered cubic metal layer mainly composed of Cr, a target for a body-centered cubic metal layer mainly composed of Cr was sputtered at 100 nm. As comparative examples, the same combinations as shown in Tables 7 and 8 were used, except that pure Cr was used for the first underlayer, and the same as above without the second underlayer.

[0024]

[Table 4]

[0025]

[Table 5]

[0026]

[Table 6]

[0027]

[Table 7]

[0028]

[Table 8]

Table 4 shows the measurement results of the coercive force squareness ratio S ^* (= Hc '/ Hc) for evaluating the coercive force Hc and noise of each substrate measured by a VSM (vibrating sample magnetometer). . Here, Hc ′ is H at the intersection of the tangent at the point Hc and the perpendicular at the point of the residual magnetization Mr in the magnetic hysteresis curve. From Tables 4 to 8, Sample No. 1-27
Is the sample No. It can be seen that the coercive force and the coercive force squareness ratio are higher than those of Nos. 28 to 36. Therefore, a Co-based magnetic layer is formed on an underlayer such as a first underlayer having a body-centered cubic regular lattice on a nonmagnetic substrate and a nonmagnetic second underlayer having an hcp structure formed on the first underlayer. It is understood that a magnetic recording medium having high coercive force and low noise can be achieved by forming the layer.

[0030]

According to the present invention, a first underlayer having a body-centered cubic regular lattice formed on the substrate side and a nonmagnetic second underlayer having an hcp structure formed on the first underlayer. By providing the underlayer, it has become possible to provide a magnetic recording medium having a high coercive force and low noise which can respond to recent high recording density.

[Brief description of the drawings]

FIG. 1 is a view showing a crystal structure of hcp.

FIG. 2 is a view showing a crystal structure of a B2 ordered lattice.

FIG. 3 is a diagram showing a crystal structure of an L2 ₁ ordered lattice.

FIG. 4 is a diagram showing a crystal structure of a DO ₃ regular lattice.

FIG. 5 is a diagram showing a crystal structure of a C11b ordered lattice.

FIG. 6 is a view showing a crystal structure of pure Cr.

Claims (7)

[Claims] 1. An in-plane magnetic recording medium having a magnetic layer formed on a nonmagnetic substrate via an underlayer, wherein the underlayer has a body-centered cubic regular lattice on the nonmagnetic substrate side. A first underlayer, and a nonmagnetic second underlayer having an hcp structure formed on the first underlayer.
An in-plane magnetic recording medium, which is an o-based magnetic layer. 2. The longitudinal magnetic recording medium according to claim 1, further comprising a body-centered cubic metal layer mainly composed of Cr between the first underlayer and the second underlayer. . 3. The longitudinal magnetic recording medium according to claim 1, wherein the body-centered cubic regular lattice as the first underlayer is a B2 regular lattice. 4. The method according to claim 1, wherein the first underlayer is made of a NiAl alloy B2.
3. The longitudinal magnetic recording medium according to claim 1, wherein the medium is a regular lattice. 5. The longitudinal magnetic recording medium according to claim 1, wherein the second underlayer is made of a CoCr-based alloy. 6. The longitudinal magnetic recording medium according to claim 1, wherein the second underlayer is made of a Ru-based alloy. 7. The method according to claim 7, wherein (C) is an additive element of the Co-based magnetic layer.
7. The composition according to claim 1, wherein at least one of r, Pt, Pd, Ni, Ti, V, Ta, W, and B) is contained in a total of 15 at% or more. In-plane magnetic recording medium.