JP3476741B2 - Magnetic recording medium and magnetic storage device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a magnetic recording medium and a magnetic storage device, and more particularly to a magnetic recording medium and a magnetic storage device suitable for high density recording.

[0002]

2. Description of the Related Art The recording density of a horizontal magnetic recording medium such as a magnetic disk has significantly increased due to the reduction of medium noise and the development of a magnetoresistive head and a spin valve head. A typical magnetic recording medium has a structure in which a substrate, an underlayer, a magnetic layer, and a protective layer are laminated in this order.
The underlayer is made of Cr or a Cr-based alloy, and the magnetic layer is C
It consists of o-based alloy.

Various methods for reducing the medium noise have been proposed so far. For example, Okamoto et a
L., "Rigid Disk Medium For
5Gbit / in ² Recording ”, AB-
3, Intermag '96 Digest has C
It has been proposed to reduce the grain size and size distribution of the magnetic layer by reducing the film thickness of the magnetic layer with a suitable underlayer of rMo. Also, US Pat.
No. 693,426 proposes to use an underlayer made of NiAl. Furthermore, Hosoe et a
L., "Experimental Study o
f Thermal Decay in High- De
nity Magnetic Recording
Media ”, IEEE Trans. Magn.
Vol. 33, 1528 (1997), CrT
It has been proposed to use an underlayer consisting of i. The underlayer as described above promotes in-plane orientation of the magnetic layer to increase remanent magnetization and thermal stability of the bit. It has also been proposed to reduce the thickness of the magnetic layer to improve resolution or reduce the transition width between written bits. Furthermore,
Promotes the segregation of Cr in the magnetic layer made of a CoCr alloy,
It has also been proposed to reduce exchange coupling between particles.

However, as the grains in the magnetic layer become smaller and become more magnetically isolated from each other, the written bits are
Destabilization and thermal activation, which increase with linear density, cause instability. Lu et al., "Thermal
Instability at 10 Gbit / in
² Magnetic Recording ”, IE
EE Trans. Magn. Vol. 30, 4
230 (1994), 400kfci at 10nm diameter by micromagnetic simulation.
It has been announced that a medium in which exchange coupling of particles with a ratio of Ku V / kB T to 60 in bit is suppressed is susceptible to a large thermal decay. Here, Ku is a constant of magnetic anisotropy, V is an average volume of magnetic particles, kB is a Boltzmann constant, and T is a temperature. The ratio of Ku V / kB T is also called a thermal stability coefficient.

Abarra et al., "The
rmal Stability of Narrow
Track Bits in a 5 Gbit / in
² Medium ”, IEEE Trans. Mag
n. Vol. 33, 2995 (1997), the existence of exchange interactions between particles stabilizes the written bit by 5 Gbit / in ² CoCrPtTa.
/ Reported by MFM analysis of annealed 200 kfci bits of CrMo media. However, at a recording density of ²⁰ Gbit / in ² or more, further suppression of magnetic coupling between particles is essential.

A reasonable solution to this has been to increase the magnetic anisotropy of the magnetic layer. However, in order to increase the magnetic anisotropy of the magnetic layer, a large load is applied to the write magnetic field of the head.

Further, the coercive force of a thermally unstable magnetic recording medium is described by He et al., "High Speed S".
watching in Magnetic Reco
rding Media ", J. Magn. Ma
gn. Mater. Vol. 155, 6 (199
6) on magnetic tape media, and in J.
H. Richter, "Dynamic Coer
civic Effects in Thin Fi
lm Media ", IEEE Trans. Mag.
n. Vol. 34, 1540 (1997) for magnetic disk media, a sharp increase with decreasing switch time. Therefore, the data speed is adversely affected. That is, how fast the data can be written in the magnetic layer and the magnetic field strength of the head necessary for reversing the magnetization of the magnetic particles rapidly increase as the switch time decreases.

On the other hand, as another method for improving the thermal stability, there has been proposed a method of increasing the orientation rate of the magnetic layer by subjecting the substrate under the magnetic layer to an appropriate texture treatment. For example, the Akimoto et a being issued
L., "Magnetic Relaxation i
n Thin Film Media as a Fu
nction of Orientation ”,
J. Magn. Magn. Mater. (19
99), it was reported by micromagnetic simulation that the effective Ku V / kB T value increases with a slight increase in the orientation ratio. As a result, A
barra et al. , "The Effect
of Orientation Ratio on t
he Dynamic Coercity of
Media for> 15Gbit / in ² Rec
ordering ”, EB-02, Intermag
As reported in '99, Korea,
It is possible to further weaken the time dependence of the coercive force that improves the overwrite performance of the magnetic recording medium.

Further, a keeper magnetic recording medium for improving thermal stability has also been proposed. The keeper layer is composed of a soft magnetic layer parallel to the magnetic layer. This soft magnetic layer is arranged above or below the magnetic layer. In many cases, a Cr magnetic insulating layer is provided between the soft magnetic layer and the magnetic layer. The soft magnetic layer reduces the demagnetizing field of the bits written in the magnetic layer. However, the purpose of decoupling the grains of the magnetic layer cannot be achieved due to the coupling of the soft magnetic layer that is continuously exchange coupled with the magnetic recording layer. As a result, medium noise increases.

[0010]

Various methods for improving thermal stability and reducing medium noise have been proposed. However, the proposed method cannot significantly improve the thermal stability of the written bits, which makes it difficult to significantly reduce the medium noise. Further, depending on the proposed method, there is also a problem that the performance of the magnetic recording medium is adversely affected because of measures for reducing the medium noise.

Specifically, in order to obtain a magnetic recording medium having high thermal stability, (i) the magnetic anisotropy constant Ku is increased, (ii) the temperature T is decreased, or (iii) magnetic property. Measures such as increasing the particle volume V of the layer can be considered.
However, with the measure (i), the coercive force increases, and it becomes more difficult to write information in the magnetic layer. On the other hand, the measure (ii) is impractical considering that the operating temperature of a disk drive or the like may exceed 60 ° C., for example. Further, the measure (iii) increases the medium noise as described above. It is also possible to increase the film thickness of the magnetic layer instead of the measure (iii),
This method reduces the resolution. Therefore, the present invention improves the thermal stability of written bits, reduces medium noise, and enables reliable high-density recording without adversely affecting the performance of the magnetic recording medium. An object of the present invention is to provide a magnetic recording medium and a magnetic storage device capable of improving recording resolution by improving in-plane orientation.

[0012]

Above problems SUMMARY OF THE INVENTION may, that Do from a ferromagnetic layer, a nonmagnetic coupling layer provided on the ferromagnetic layer
And exchange換層structure, with a magnetic layer provided on the exchange layer structure, the ferromagnetic layer and the magnetic layer are exchange-coupled,
The magnetization directions are antiparallel to each other, and the nonmagnetic coupling layer is R
This is achieved by a magnetic recording medium characterized in that it is made of a material in which u is added with an element selected from the group consisting of Co, Cr, Fe, Ni, Mn or an alloy of these elements. According to the present invention, the thermal stability of written bits can be improved, medium noise can be reduced, and reliable high-density recording can be performed without adversely affecting the performance of the magnetic recording medium. A magnetic recording medium capable of improving the recording resolution can be realized by improving the in-plane orientation.

[0013]

The above-mentioned problems are caused by the first ferromagnetic layer and the first ferromagnetic layer.
A first non-magnetic coupling layer provided on the ferromagnetic layer of
A second ferromagnetic layer provided on the first non-magnetic coupling layer;
A second non-magnetic coupling layer provided on the second ferromagnetic layer,
And the second non-magnetic coupling of the exchange layer structure.
A magnetic layer provided on the composite layer, the first ferromagnetic layer
And the second ferromagnetic layer are exchange-coupled and the magnetization directions are mutually
It is antiparallel to each other, and the second ferromagnetic layer and the magnetic layer are exchanged.
Are coupled and their magnetization directions are antiparallel to each other,
The non-magnetic coupling layer is made of Ru, Co, Cr, Fe, Ni, M
elements selected from the group consisting of n or their elements
It is composed of a material to which an elemental alloy is added.
The nonmagnetic coupling layer is made of Ru, Co, Cr, Fe, Ni, Mn.
An element selected from the group consisting of or these elements
Is composed of a material to which the alloy of
The magnetization directions of the second ferromagnetic layer should cancel each other.
It is also achieved by a magnetic recording medium characterized by: Ru
The proportion of elements added to is 50 at% or less for Co, 50 at% or less for Cr, and 60 a for Fe.
It may be selected to be t% or less, 10 at% or less for Ni, and 50 at% or less for Mn.

The nonmagnetic coupling layer has a thickness of 0.4 to 1.0 nm.
The film thickness may be selected within the range.

The ferromagnetic layer is made of Co, Ni, Fe, Ni.
Alloys, Fe alloys, CoCrTa, CoCrP
t, made of a material selected from the group consisting of Co-based alloys containing CoCrPt-M2, and M2 = B, Mo, N
It may be b, Ta, W, Cu or an alloy thereof.

The magnetic layer comprises Co and CoCrTa,
It is made of a material selected from the group consisting of Co-based alloys including CoCrPt and CoCrPt-M4, and M4 =
It may be B, Mo, Nb, Ta, W, Cu or an alloy thereof.

The above object can also be achieved by a magnetic storage device including at least one magnetic recording medium having any one of the above configurations. According to the present invention, the thermal stability of written bits can be improved, medium noise can be reduced, and reliable high-density recording can be performed without adversely affecting the performance of the magnetic recording medium. It is possible to realize a magnetic memory device capable of improving the recording resolution by improving the in-plane orientation.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

[0020]

First, the operating principle of the present invention will be described.

The present invention uses multiple layers having magnetized structures that are antiparallel to each other. For example, S. S.
P. Parkin, "Systematic Va
riation of the Strength a
nd Oscillation Period of
Indirect Magnetic Exchange
e Coupling through the 3d,
4d, and 5d Transition Me
tals ", Phys. Rev. Lett. V.
ol. 67, 3598 (1991), R
Magnetic transition metals such as Co, Fe and Ni which are coupled to the magnetic layer through a thin non-magnetic intermediate layer such as u and Rh have been described. On the other hand, in US Pat. No. 5,701,223,
In order to stabilize the sensor, there has been proposed a spin valve using the above layers as a laminated pinning layer.

When the Ru or Rh layer provided between the two ferromagnetic layers has a specific film thickness, the magnetization directions of the ferromagnetic layers can be made parallel or antiparallel to each other. For example,
In the case of a structure including two ferromagnetic layers having different film thicknesses and antiparallel magnetization directions, the effective particle size of the magnetic recording medium can be increased without substantially affecting the resolution. The signal amplitude reproduced from such a magnetic recording medium is reduced by the magnetization in the opposite direction. For this, an additional layer having an appropriate film thickness and magnetization direction is provided under the laminated magnetic layer structure. Thus, the influence of one layer can be canceled out. As a result, the amplitude of the signal reproduced from the magnetic recording medium can be increased and the effective particle volume can be increased. Therefore, a written bit with high thermal stability can be realized.

The present invention improves the thermal stability of written bits by either exchange coupling the magnetic layer with the other ferromagnetic layers in the opposite magnetization direction or by using a laminated ferrimagnetic structure. The ferromagnetic layer or laminated ferrimagnetic structure consists of a magnetic layer of exchange-decoupled particles. That is, the present invention uses the exchange pinning ferromagnetic layer or the ferrimagnetic multilayer structure to improve the thermal stability performance of the magnetic recording medium.

FIG. 1 shows a first magnetic recording medium according to the present invention.
It is sectional drawing which shows the principal part of an Example. The magnetic recording medium includes a nonmagnetic substrate 1, a first seed layer 2, a NiP layer 3, a second seed layer 4, an underlayer 5, a nonmagnetic intermediate layer 6, a ferromagnetic layer 7, a nonmagnetic coupling layer 8, and a magnetic layer. Layer 9, protective layer 10 and lubricating layer 11
However, as shown in FIG. 1, it has a structure laminated in this order.

For example, the non-magnetic substrate 1 is made of Al, Al alloy or glass. This non-magnetic substrate 1 may or may not be textured. First
The seed layer 2 is made of NiP, especially when the non-magnetic substrate 1 is made of glass. The NiP layer 3 may or may not be textured or oxidized. The second seed layer 4 is formed by forming NiA on the underlayer 5.
It is provided to improve the orientation of the (001) plane or the (112) plane of the underlayer 5 when an alloy having a B2 structure such as 1, FeAl or the like is used. The second seed layer 4 is made of a suitable material similar to that of the first seed layer 2.

When the magnetic recording medium is a magnetic disk, the texture treatment applied to the non-magnetic substrate 1 or the NiP layer 3 is
This is performed along the circumferential direction of the disk, that is, the direction in which the tracks on the disk extend.

The non-magnetic intermediate layer 6 has an epitaxial growth of the magnetic layer 9, a reduction in grain distribution width, and an anisotropic axis (easy axis of magnetization) of the magnetic layer 9 along a plane parallel to the recording surface of the magnetic recording medium. It is provided to promote orientation. The non-magnetic intermediate layer 6 is made of an alloy having an hcp structure such as CoCr-M and has a film thickness selected in the range of 1 to 5 nm. Here, M = B, Mo, Nb, Ta, W or an alloy thereof.

The ferromagnetic layer 7 is made of Co, Ni, Fe, Co-based alloy, Ni-based alloy, Fe-based alloy, or the like. That is, C
C containing oCrTa, CoCrPt, CoCrPt-M
An o-based alloy can be used for the ferromagnetic layer 7. Here, M = B, Mo, Nb, Ta, W or an alloy thereof. This ferromagnetic layer 7 has a film thickness selected in the range of 2 to 10 nm. The nonmagnetic coupling layer 8 is made of Ru, Rh, I
r, Ru-based alloy, Rh-based alloy, Ir-based alloy, or the like.
For example, the non-magnetic coupling layer 8 has a film thickness selected in the range of 0.4 to 1.0 nm, preferably about 0.6 to
It has a film thickness of 0.8 nm. By selecting the film thickness of the nonmagnetic coupling layer 8 in such a range, the magnetization directions of the ferromagnetic layer 7 and the magnetic layer 9 are antiparallel to each other. The ferromagnetic layer 7 and the non-magnetic coupling layer 8 form an exchange layer structure.

The magnetic layer 9 is made of Co, CoCrTa, Co.
It is made of a Co-based alloy containing CrPt or CoCrPt-M. Here, M = B, Mo, Nb, Ta, W or an alloy thereof. The magnetic layer 9 has a film thickness selected in the range of 5 to 30 nm. Of course, it goes without saying that the magnetic layer 9 is not limited to a single layer structure, and may have a multilayer structure.

The protective layer 10 is made of C, for example. The lubricant layer 11 is made of an organic lubricant for using the magnetic recording medium with a magnetic transducer such as a spin valve head. The protective layer 10 and the lubricating layer 11 form a protective layer structure on the magnetic recording medium.

The layer structure provided below the exchange layer structure is, of course, not limited to that shown in FIG. For example, the base layer 5
Is made of Cr or a Cr-based alloy, and is 5 to 40 on the substrate 1.
The exchange layer structure is formed with a thickness selected in the range of nm.
It may be provided on such a base layer 5.

Next, a second embodiment of the magnetic recording medium according to the present invention will be described.

FIG. 2 shows a second magnetic recording medium according to the present invention.
It is sectional drawing which shows the principal part of an Example. In the figure, those parts which are the same as those corresponding parts in FIG. 1 are designated by the same reference numerals, and a description thereof will be omitted.

In the second embodiment of this magnetic recording medium, the exchange layer structure comprises two non-magnetic coupling layers 8, 8-1 and two ferromagnetic layers 7, 7-1 constituting a ferrimagnetic multilayer structure. Become. By using such a structure, the magnetizations of the two non-magnetic coupling layers 8 and 8-1 cancel each other without canceling a part of the magnetic layer 9, so that the effective magnetization and the signal can be increased. Becomes As a result, the grain volume of the magnetic layer 9 and the thermal stability of magnetization are effectively increased. As long as the orientation of the easy axis of magnetization of the recording layer is preferably maintained, the effective two-layer structure composed of the pair of the ferromagnetic layer and the nonmagnetic layer can increase the effective grain volume.

The ferromagnetic layer 7-1 is made of the same material as that of the ferromagnetic layer 7, and its film thickness is selected in the same range as that of the ferromagnetic layer 7. The non-magnetic coupling layer 8-1 is made of the same material as the non-magnetic coupling layer 8 and the film thickness is selected in the same range as the non-magnetic coupling layer 8. Between the ferromagnetic layers 7 and 7-1, the c-axis is substantially along the in-plane direction, and the grains grow in a columnar shape.

In this embodiment, the magnetic anisotropy of the ferromagnetic layer 7-1 is set higher than that of the ferromagnetic layer 7. The magnetic anisotropy of the ferromagnetic layer 7-1 may be stronger, weaker, or the same as the magnetic anisotropy of the magnetic layer 9. The point is that the magnetic anisotropy of the ferromagnetic layer 7 should be weaker than that of the upper and lower layers 9 and 7-1.

The product of the residual magnetization and the film thickness of the ferromagnetic layer 7 is
It is set smaller than the product of the residual magnetization and the film thickness of the ferromagnetic layer 7-1.

FIG. 3 shows a film thickness 10 formed on a Si substrate.
FIG. 6 is a diagram showing in-plane magnetic characteristics of a single CoPt layer of nm. In FIG. 3, the vertical axis represents the magnetization (emu) and the horizontal axis represents the coercive force (O
e) is shown. The conventional magnetic recording medium exhibits the characteristics shown in FIG.

FIG. 4 shows two Co layers separated by a Ru layer having a film thickness of 0.8 nm as in the first embodiment of the recording medium.
It is a figure which shows the in-plane magnetic characteristic of a Pt layer. In FIG. 4, the vertical axis represents the residual magnetization (Gauss) and the horizontal axis represents the coercive force (Oe). As can be seen from FIG. 4, the loop causes a shift near the coercive force, and antiferromagnetic coupling occurs. Fig. 5 shows the two separated Ru layers with a thickness of 1.4 nm.
It is a figure which shows the in-plane magnetic characteristic of one CoPt layer. Figure 5
The middle axis represents the remanent magnetization (emu) on the vertical axis and the coercive force (Oe) on the horizontal axis.
Indicates. As can be seen from FIG. 5, the magnetization directions of the two CoPt layers are parallel.

FIG. 6 is a diagram showing in-plane magnetic characteristics of two CoCrPt layers separated by a Ru layer having a thickness of 0.8 nm as in the second embodiment. In FIG. 6, the vertical axis represents the residual magnetization (emu / cc) and the horizontal axis represents the coercive force (Oe). As can be seen from FIG. 6, it can be seen that the loop shifts near the coercive force and antiferromagnetic coupling occurs.

From FIGS. 3 and 4, it is understood that antiparallel coupling can be obtained by providing the exchange layer structure. Further, as can be seen by comparing FIG. 5 with FIGS. 4 and 6, the thickness of the non-magnetic coupling layer 8 is preferably in the range of 0.4 to 1.0 nm in order to obtain antiparallel coupling. Is selected.

Therefore, according to the first and second embodiments of the magnetic recording medium, the exchange coupling between the magnetic layer and the ferromagnetic layer via the non-magnetic coupling layer does not sacrifice the resolution.
The effective particle volume can be increased. That is, the apparent film thickness of the magnetic layer can be increased from the viewpoint of particle volume so that a medium having good thermal stability can be realized. Further, since the reproduction output from the lower magnetic layer is canceled, the effective film thickness of the magnetic layer does not change. As a result, the apparent magnetic layer thickness increases, but the effective magnetic layer thickness can be reduced without change, so that high resolution that cannot be obtained with a thick medium can be obtained. As a result, it is possible to obtain a magnetic recording medium with reduced medium noise and improved thermal stability.

Next, an embodiment of the magnetic storage device according to the present invention will be described with reference to FIGS. FIG. 7 is a sectional view showing a main part of an embodiment of the magnetic storage device, and FIG. 8 is a plan view showing a main part of the embodiment of the magnetic storage device.

As shown in FIGS. 7 and 8, the magnetic storage device generally comprises a housing 13. In the housing 13, a motor 14, a hub 15, a plurality of magnetic recording media 16,
Multiple recording / reproducing heads 17, multiple suspensions 1
8, a plurality of arms 19 and an actuator unit 20
Is provided. The magnetic recording medium 16 is attached to the hub 15 rotated by the motor 14. The recording / reproducing head 17 includes a reproducing head such as an MR head or a GMR head, and a recording head such as an inductive head. Each recording / reproducing head 17 is attached to the tip of a corresponding arm 19 via a suspension 18.
The arm 19 is driven by the actuator unit 20. The basic configuration itself of this magnetic storage device is well known,
Detailed description thereof will be omitted in the present specification.

This embodiment of the magnetic storage device is characterized by the magnetic recording medium 16. Each magnetic recording medium 16 has the structure of the first or second embodiment of the magnetic recording medium described with reference to FIGS. 1 and 2, or the third embodiment of the magnetic recording medium described later with reference to FIGS. Have a structure. Of course, the number of magnetic recording media 16 is not limited to three, and may be one, two, or four or more.

The basic structure of the magnetic storage device is shown in FIGS.
It is not limited to those shown in. The magnetic recording medium used in the present invention is not limited to the magnetic disk.

By the way, when Ru is used for the non-magnetic coupling layer 8 and CoCr-based alloy is used for the magnetic layer 9 in the magnetic recording medium having the exchange layer structure as in the first embodiment shown in FIG. Both layers 8 and 9 have an hcp structure. In order to increase both the coercive force and the resolution of the magnetic recording medium, it is desirable that the c-axis of the hcp structure be parallel to the surface of the substrate 1. When a CoCr-based alloy is used for the ferromagnetic layer 7, the ferromagnetic layer 7 is made of an alloy having an hcp structure (00
2) Since the epitaxial layer is epitaxially grown on the intermediate layer 6 oriented in the plane, the in-plane orientation of the c-axis of the ferromagnetic layer 7 is good.

On the other hand, Ru used for the non-magnetic coupling layer 8
Has an hcp structure similar to the CoCr alloy, but R
The lattice constant of u is about 5% wider than that of CoCr alloy. Therefore, the ferromagnetic layer 7 and the non-magnetic coupling layer 8
Or between the non-magnetic coupling layer 8 and the magnetic layer 9,
The epitaxial growth may be slightly hindered due to the lattice mismatch. As described above, if the epitaxial growth is slightly hindered due to the lattice mismatch, the coercive force of the magnetic recording medium is lowered and the in-plane orientation of the c-axis of the CoCr-based alloy becomes unstable.

Therefore, the epitaxial growth between Ru and the CoCr-based alloy is improved, the coercive force of the magnetic recording medium is increased, and the c-axis in-plane orientation of the CoCr-based alloy is improved. An example in which the recording resolution characteristic can be improved will be described below. FIG. 9 is a sectional view showing the main part of a third embodiment of the magnetic recording medium according to the present invention. The magnetic recording medium includes a nonmagnetic substrate 16, a seed layer 17, an underlayer 18 made of a Cr-based alloy, a nonmagnetic intermediate layer 19, and a ferromagnetic layer 2.
0, the non-magnetic coupling layer 21, the magnetic layer 22, the protective layer 23, and the lubricating layer 24 are laminated in this order as shown in FIG.

The non-magnetic substrate 16 is made of, for example, Al alloy or glass. The nonmagnetic substrate 16 may or may not be textured. Seed layer 1
No. 7 is made of NiP formed by plating when the non-magnetic substrate 16 is made of Al alloy. The NiP seed layer 17 may or may not be textured. When the non-magnetic substrate 16 is made of glass, the seed layer 17 is made of an intermetallic compound material having a B2 structure such as NiAl and FeAl.

The non-magnetic intermediate layer 19 is formed by epitaxial growth of the magnetic layer 22, reduction of grain size distribution width, and anisotropy axis (c-axis, magnetization) of the magnetic layer 22 along a plane parallel to the recording surface of the magnetic recording medium. It is provided to promote the (easy axis) orientation. The non-magnetic intermediate layer 19 is made of an alloy having an hcp structure such as CoCr-M1 and has a film thickness selected in the range of about 1 to 5 nm. Here, M1 = B, Mo,
Bn, Ta, W or alloys thereof.

The ferromagnetic layer 20 is made of Co, Ni, Fe, Co.
It is made of a system alloy, a Ni system alloy, a Fe system alloy, or the like. That is,
A Co-based alloy containing CoCrTa, CoCrPt, CoCrPt-M2 can be used for the ferromagnetic layer 20. Here, M2 = B, Mo, Nb, Ta, W or an alloy thereof. This ferromagnetic layer 20 has a film thickness selected in the range of approximately 2 to 10 nm.

The non-magnetic coupling layer 21 is made of Ru-M3 hc.
It is made of an alloy having ap structure. Here, M3 = Co, C
r, Fe, Ni, Mn or alloys thereof. The non-magnetic coupling layer 21 has a film thickness selected in the range of, for example, about 0.4 to 1.0 nm, preferably about 0.6 to 0.8 nm.
Has a film thickness of. By selecting the film thickness of the non-magnetic coupling layer 21 to such a value, the ferromagnetic layer 20 and the magnetic layer 22 are
Magnetization directions are antiparallel to each other. Thus, the ferromagnetic layer 20 and the nonmagnetic coupling layer 19 form an exchange layer structure.

The magnetic layer 22 is made of Co or CoCrTa, C.
It is made of a Co-based alloy containing oCrPt and CoCrPt-M4. Here, M4 = B, Mo, Nb, Ta, W or an alloy thereof. This magnetic layer 22 has a thickness of about 5 to 30 nm.
The film thickness is selected within the range. Of course, it goes without saying that the magnetic layer 22 is not limited to a single-layer structure and may have a multi-layer structure.

The protective layer 23 is made of C or DLC.
Further, the lubricating layer 24 is made of an organic lubricant for using a magnetic transducer such as a spin valve head for the magnetic recording medium. The protective layer 23 and the lubricating layer 24 constitute a protective layer structure of the magnetic recording medium.

As described above, the nonmagnetic coupling layer 21 is made of Ru-
Made of an alloy M3, M3 = Co, Cr, Fe, N
i, Mn or alloys thereof. In this embodiment, Ru
The addition amount of the element M3 added to the above is preferably in the following composition range so that a stable hcp structure is maintained. The value in parentheses following the additional element M3 added to Ru is atomic%
(At%) is shown.

Ru-Co (0 to 50 at%) Ru-Cr (0 to 50 at%) Ru-Fe (0 to 60 at%) Ru-Ni (0 to 10 at%) Ru-Mn (0 to 50 at%) Is the non-magnetic coupling layer 21 of the magnetic recording medium shown in FIG.
It is a figure which shows the magnetization curve obtained when pure Ru is used for. In the figure, the vertical axis represents the magnetization M (arbitrary unit) and the horizontal axis represents the magnetic field H.
(KOe) is shown. The magnetization curve shown in the figure was measured by a vibrating sample magnetometer while applying a magnetic field parallel to the sample surface, that is, the recording surface of the magnetic recording medium. Since there is a region where the ferromagnetic layer 20 and the magnetic layer 22 are coupled antiparallel to each other, the magnetization curve has a constriction.

The magnetization curve obtained when an alloy of Ru-M3 was used for the non-magnetic coupling layer 21 was also measured in the same manner. Even when an alloy of Ru-M3 is used for the non-magnetic coupling layer 21, there is a region where the ferromagnetic layer 20 and the magnetic layer 22 are coupled antiparallel to each other, as in the case of FIG. Was confirmed to occur.

In FIG. 10, in the first and fourth quadrants, the linear portion of the magnetization curve on the higher magnetic field side than the constriction is extrapolated to the magnetic field axis, and the intersection with the magnetic field axis is defined as the in-plane coercive force Hc //. Define.

FIG. 11 is a diagram showing a magnetization curve measured by a vertical Kerr looper while applying a magnetic field in a direction perpendicular to the sample surface with respect to the magnetic recording medium for which the data of FIG. 10 was measured. is there. In FIG. 11, the vertical axis represents Kerr rotation (degrees) and the horizontal axis represents the vertical magnetic field (Oe). The perpendicular coercive force Hc⊥ is shown in FIG.

The degree of in-plane orientation of the easy axis of magnetization of the magnetic layer 22 can be evaluated by the ratio of (Hc⊥) / (Hc //). The smaller the ratio (Hc⊥) / (Hc //), the better the in-plane orientation of the magnetic layer 22.

The measurement results of the in-plane coercive force Hc // and the ratio (Hc⊥) / (Hc //) when various materials are used for the non-magnetic coupling layer 21 are shown below. The in-plane coercive force Hc // for various materials is shown as a relative value when the in-plane coercive force Hc // when pure Ru is used for the non-magnetic coupling layer 21 is 1. Non-magnetic coupling layer 21 Hc // (relative value) (Hc⊥) / (Hc //) Ru 1 0.33 Ru-Co (20 at%) 1.10 0.23 Ru-Cr (20 at%) 1.05 0.25 Ru-Fe (20 at%) 1.07 0.28 Ru-Mn (20 at%) 0.96 0.30 Ru-Ni (10 at%) 0.94 0.30 Thus, in this Example. According to this, no matter which alloy of Ru-M3 is used for the non-magnetic coupling layer 21, an improvement in the ratio (Hc⊥) / (Hc //) is confirmed as compared with the case of using pure Ru. It was It was also confirmed that such an improvement in the in-plane orientation of the magnetic layer 22 improves the recording resolution by about 1.5 to 2.5%.

Moreover, hc of Ru used for the non-magnetic coupling layer 21
Even if the spacing of the (002) planes of the p structure is about 8% in the worst case with the upper and lower ferromagnetic layers 20 and 22 and usually about 5% at the maximum, the above It was confirmed that the lattice mismatch can be reduced to about 6% or less, preferably 2% or less by adding the element M3 to Ru. Further, as the element M3 which can be added to Ru, the above Co, Cr, Fe, Ni, Mn or alloys thereof are preferable, but not limited to these, and for example Ir, Mo, N
The lattice mismatch may be adjusted by using b, Pt, Rh, Ta, Ti, V, W or an alloy thereof.

This embodiment is the second embodiment of the magnetic recording medium.
It goes without saying that the structure of the embodiment can be applied in the same manner.

The present invention has been described above with reference to the embodiments.
Needless to say, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made.

[0066]

According to the present invention, the thermal stability of written bits is improved, the medium noise is reduced, and highly reliable high density recording can be performed without adversely affecting the performance of the magnetic recording medium. Particularly, it is possible to realize a magnetic recording medium and a magnetic storage device capable of improving the recording resolution by improving the in-plane orientation of the magnetic layer.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a first embodiment of a magnetic recording medium according to the present invention.

FIG. 2 is a sectional view showing an essential part of a second embodiment of the magnetic recording medium according to the present invention.

FIG. 3 is a diagram showing in-plane magnetic characteristics of a single CoPt layer having a film thickness of 10 nm formed on a Si substrate.

FIG. 4 is a diagram showing in-plane magnetic characteristics of two CoPt layers separated by a Ru layer having a thickness of 0.8 nm.

FIG. 5 is a diagram showing in-plane magnetic characteristics of two CoPt layers separated by a Ru layer having a film thickness of 1.4 nm.

FIG. 6 is a diagram showing in-plane magnetic characteristics of two CoCrPt layers separated by a Ru layer having a film thickness of 0.8 nm.

FIG. 7 is a sectional view showing a main part of an embodiment of a magnetic memory device according to the present invention.

FIG. 8 is a plan view showing a main part of an embodiment of a magnetic storage device.

FIG. 9 is a sectional view showing an essential part of a third embodiment of the magnetic recording medium according to the present invention.

FIG. 10 is a diagram showing a magnetization curve obtained when pure Ru is used for a nonmagnetic coupling layer of a magnetic recording medium.

FIG. 11 is a diagram showing a magnetization curve measured by a vertical curlper while applying a magnetic field in a direction perpendicular to the sample surface.

[Explanation of symbols]

16 substrates 17 Seed layer 18 Underlayer 19 Non-magnetic intermediate layer 20 Ferromagnetic layer 21 Non-magnetic Coupling Layer 22 Magnetic layer 23 Protective layer 24 Lubrication layer

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-6-349047 (JP, A) JP-A-9-138935 (JP, A) JP-A-9-198641 (JP, A) JP-A-11- 328646 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 5/66

Claims (11)

(57) [Claims] With a 1. A ferromagnetic layer, and the exchange換層structure ing from a non-magnetic coupling layer provided on the ferromagnetic layer, and a magnetic layer provided on the exchange layer structure, said strong The magnetic layer and the magnetic layer are exchange-coupled, and the magnetization directions are antiparallel to each other. The non-magnetic coupling layer includes Ru, Co, Cr, Fe, Ni, and M.
A magnetic recording medium, comprising a material to which an element selected from the group consisting of n or an alloy of these elements is added. 2. The proportion of elements added to Ru is 50 at% or less for Co and 50 at% or less for Cr,
60 at% or less for Fe, 10 at% for Ni
Hereinafter, the case of Mn, characterized in that it is chosen below 50at%, claim 1 magnetic recording medium according. 3. The nonmagnetic coupling layer is 0.4 to 1.0 n
3. The magnetic recording medium according to claim 1, which has a film thickness selected within the range of m. 4. The ferromagnetic layer is made of Co, Ni, Fe, N.
i-based alloy, Fe-based alloy, CoCrTa, CoCrP
t, made of a material selected from the group consisting of Co-based alloys containing CoCrPt-M2, and M2 = B, Mo, N
b, Ta, W, Cu or wherein the alloys thereof, the magnetic recording medium of any one of claims 1-3. 5. The magnetic layer comprises Co and CoCrT.
a, a material selected from the group consisting of Co-based alloys including CoCrPt and CoCrPt-M4, M4
= B, Mo, Nb, Ta, W, Cu or alloys thereof, The magnetic recording medium according to claim 1. 6. A first ferromagnetic layer and on the first ferromagnetic layer
And a first non-magnetic coupling layer provided on the first non-magnetic coupling layer.
A second ferromagnetic layer provided on the composite layer, and the second ferromagnetic layer
Exchange layer comprising a second non-magnetic coupling layer provided on the layer
Structure and a magnetic layer provided on the second non-magnetic coupling layer of the exchange layer structure.
A sexual layer, the first ferromagnetic layer and the second ferromagnetic layer exchange-coupled
The magnetization directions of both are antiparallel to each other , and the second ferromagnetic layer and the magnetic layer are exchange-coupled and magnetized.
The directions are antiparallel to each other, and the first nonmagnetic coupling layer is formed of Ru, Co, Cr, Fe, N.
an element selected from the group consisting of i and Mn, or this
The second non-magnetic coupling layer is made of a material to which an alloy of these elements is added, and the second non-magnetic coupling layer contains Ru, Co, Cr, Fe and N.
an element selected from the group consisting of i and Mn, or this
It is composed of a material to which an alloy of these elements is added, and the magnetization directions of the first and second ferromagnetic layers cancel each other out.
A magnetic recording medium characterized by mutual contact. 7. The ratio of elements added to Ru is Co
In case of 50 at% or less, in case of Cr 50 at% or less,
60 at% or less for Fe, 10 at% for Ni
Below, in the case of Mn, it should be selected at 50 at% or less.
7. The magnetic recording medium according to claim 6, wherein: 8. The first nonmagnetic coupling layer has a thickness of 0.4 to
Having a film thickness selected within the range of 1.0 nm,
The non-magnetic coupling layer of is selected within the range of 0.4 to 1.0 nm
6. The method according to claim 6 or 7, characterized in that
The magnetic recording medium described. 9. The first ferromagnetic layer comprises Co, Ni, F
e, Ni-based alloy, Fe-based alloy, CoCrTa, Co
Made of Co-based alloys including CrPt and CoCrPt-M2
Made of a material selected from the group consisting of
The magnetic layer is made of Co, Ni, Fe, Ni-based alloy, or Fe-based alloy.
Gold, CoCrTa, CoCrPt, CoCrPt-
Selected from the group consisting of Co-based alloys containing M2
Made of material, M2 = B, Mo, Nb, Ta, W, Cu
Or an alloy of these, 7.
9. The magnetic recording medium according to any one of items 8. 10. The magnetic layer comprises Co and CoCrT.
Co composition containing a, CoCrPt, CoCrPt-M4
Made of material selected from the group consisting of gold, M4
= B, Mo, Nb, Ta, W, Cu or alloys of these
And feature that there any one Kouki of claims 6-9
The magnetic recording medium mounted. 11. A magnetic storage device comprising at least one magnetic recording medium according to claim 1.