JPH10241937A - Magnetic recording medium and magnetic recorder using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a magnetic recording medium having a high coercive force and a high squareness ratio by improving the in-plane orientational property by using a Cr alloy film formed on a highly oriented Cr film as the substrate of a successively epitaxially grown magnetic film. SOLUTION: After a bcc (100)-oriented Cr film 5 is formed on a nonmagnetic substrate 11, a Cr alloy film 6 is formed on the Cr film 5 and the in-plane orientation property of the film 6 is improved. At the time of forming the films 5 and 6, the thickness of the film 5 is adjusted to about 5-80nm and the optimum thickness of the film 6 is decided to about 1-20nm from the relation among the magnitudes of the lattice constants of the films 5 and 6 and a magnetic film 13. The lattice constant of the film 6 is adjusted to 2.95Å by adding at least one kind of element selected from among Ti, Si, Mo, V, W, Ta, Zr, Mn, Au, Ag, Pd, Cu, Ir, Re, and Ga to Cr which is the main component of the film 6. Therefore, medium noise can be reduced by suppressing disturbances at bit boundaries.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic recording device and a magnetic recording medium using the same.

[0002]

2. Description of the Related Art With the progress of the information society, the amount of information handled on a daily basis is steadily increasing. Along with this, there is a strong demand for higher density and higher recording capacity for magnetic recording devices. When the density of a magnetic disk device, which is a typical magnetic recording device, is increased, in general, the reproduction output of a conventional electromagnetic induction type magnetic head is reduced, making reproduction difficult. For this reason, as described in Japanese Patent Application Laid-Open No. 51-44917, a recording magnetic head and a reproducing magnetic head are separated from each other. Use of a magnetic head utilizing the effect has been studied.

The magnetoresistive head has a high reproduction output and low thermal noise due to the low resistance of the head. Therefore, the noise caused by the magnetic recording medium, which has been hidden by the large noise generated from the electromagnetic induction type magnetic head, occupies a large proportion of the noise of the entire apparatus. Therefore, in order to achieve high recording density using a magnetoresistive head, it is necessary to reduce noise (medium noise) caused by a magnetic recording medium.

It is considered that the medium noise is generated because the bit boundary itself is distorted in a sawtooth shape due to the demagnetizing field generated from the bit boundary. The higher the recording density is, the larger the medium noise becomes. As a method for reducing the medium noise, there is a method for reducing the size of magnetic particles described in JP-A-8-63734. Further, a method of reducing the influence of thermal fluctuation due to miniaturization by using a high magnetic anisotropic energy material described in Japanese Patent Application Laid-Open No. 8-138228 has been studied.

[0005]

The high magnetic anisotropic energy material has a larger lattice constant than the conventional CoCrTa-based magnetic material. If a Cr film is used as an underlayer, a lattice mismatch occurs, and the coercive force decreases. If a Cr alloy film is used as a base, in-plane orientation decreases, and a sufficient coercive force and squareness cannot be obtained, which is a problem.

An object of the present invention is to improve the in-plane orientation of a Cr alloy film and obtain a high coercive force and a squareness ratio, so that a magnetic recording medium suitable for high-density recording and a square recording medium using the same are used. It is an object of the present invention to provide a magnetic recording apparatus which realizes a recording density of 1.5 gigabits per inch or more.

[0007]

The object of the present invention is to provide a highly oriented Cr.
This is achieved by forming a Cr alloy film on the film as a base for a magnetic film which is subsequently epitaxially grown.

The principle of the present invention will be described with reference to FIG. The Cr film 5 formed on the non-magnetic substrate 11 has a bcc (10
0) Orientation has been developed, and when the Cr alloy film 6 is subsequently formed, it is epitaxially grown and the bcc (100) orientation is developed. At this time, since the bulk lattice constant of the Cr alloy film 6 is larger than that of the Cr film 5,
It is considered that the lattice constant of the surface of the r alloy film 6 increases as the thickness of the Cr alloy film 6 increases, and approaches the bulk value. Therefore, if the bulk lattice constant of the Cr alloy film 6 is set to be larger than 1 / √2 times the c-axis length of the hcp structure of the magnetic film 13, the lattice constant becomes large before the Cr alloy film 6 becomes too thick and the orientation is disturbed. The thickness is such that the mismatch is eliminated, and the reduction of the anisotropic magnetic field can be suppressed.

If the Cr film 5 has a thickness of 5 nm or more, bcc
The (100) orientation develops to some extent. If the thickness exceeds 80 nm, the grains of the magnetic film 13 become too large, and the medium noise increases. The reason why the bcc (100) orientation is sufficiently developed and the medium noise is small is that the Cr film 5 has a thickness of 15n.
m or more and less than 50 nm.

[0010] The optimum thickness of the Cr alloy film 6 is the same as that of the Cr film 5 and C
It is determined from the magnitude relation between the lattice constants of the r alloy film 6 and the magnetic film 13. When the magnetic films 13 are the same, the larger the lattice constant of the Cr alloy film 6, the thinner it can be. However, as the difference between the lattice constants of the Cr film 5 and the Cr alloy film 6 increases, epitaxial growth becomes more difficult. If the lattice mismatch exceeds 6%, epitaxial growth does not occur. At this time, the thickness of the Cr alloy film 6 is about 1 nm. On the other hand, the Cr alloy film 6
If the thickness exceeds m, the orientation of the surface of the Cr alloy film 6 on the Cr film 5 having sufficiently developed bcc (100) orientation will be disturbed. If the lattice constant of the Cr alloy film 6 is less than 2.95 °, the Cr alloy film 6 may be 2
It is necessary to grow 0 nm or more. The composition of Cr at which the lattice constant of the Cr alloy film 6 becomes 2.95 ° is about 85 at% for an additive element having a relatively small atomic radius such as Ti, and about 95 at% for an additive element having a relatively large atomic radius such as W. It is.

The c-axis length of the hcp structure of the magnetic film 13 is represented by Lm, C
When the bcc structure lattice constant of the r alloy layer 6 is Lc,
If 0.72Lm <Lc <0.79Lm, the above condition is satisfied.

The composition of the Cr alloy film is Cr, Ti,
Si, Mo, V, W, Ta, Zr, Mn, Au, Ag,
When at least one element selected from Pd, Cu, Ir, W, Re, and Ga is included, the lattice constant becomes larger than Cr in the bcc structure. If the same element as that contained in the magnetic film is contained, epitaxial growth is likely to occur.
In particular, when Ti, Si, Mo, and V are included, noise is reduced because the size of the grains is uniform.

The magnetic film is an alloy mainly composed of hcp structure Co and contains Cr, Pt, Pd, and Sm.
It becomes a highly anisotropic energy material. At this time, the c-axis length is P
It is about 1% larger than the case where t, Pd, and Sm are not included. More preferably, Ta, Ti, Zr, Ni, Fe,
When at least one element selected from Mn, Au, Ag, Cu, Ir, W, Re, and Ga is included, the magnetostatic characteristics can be changed without changing the film forming conditions, and thus, it is adjusted to the device specifications. Useful for Above all, Ta, T
When i is contained, the segregation of Cr is promoted and the interaction between the magnetic particles is reduced, so that the noise is reduced. In particular, when the content of Ta is 6 at% or more, the fragmentation of the magnetic particles themselves is promoted, and the noise is reduced. To promote Cr segregation, Zr, A
u, Ag, Cu, Ir are also effective. The present invention that suppresses thermal fluctuation is effective even when the magnetic film is divided into two layers by the nonmagnetic film.

As the protective film 16 and the lubricating film 17, those generally used for magnetic disks are used as they are.

The substrate 11 is a non-magnetic, usually disk-shaped, Al-Mg alloy having a surface plated with a Ni-P alloy,
Ti alloy, tempered glass, organic resin, ceramics, or the like is used.

The head traveling direction is the circumferential direction of the disk. If the value of the product Brδ of the residual magnetic flux density Br measured in this direction and the total film thickness δ of the magnetic film exceeds 100 Gm, the MR or GMR magnetic head having high reproduction sensitivity may become unstable.

The magnetic recording medium of the present invention has a high recording density,
Since the medium noise can be reduced, by combining with an MR or GMR type magnetic head having high reproduction sensitivity,
Recording and reproduction are possible even at a high recording density of 1.5 gigabits or more per square inch.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) An embodiment of the multilayer magnetic recording medium of the present invention will be described below with reference to FIG. The magnetic recording medium of this embodiment is an Al-Mg alloy having a surface plated with a Ni-P alloy,
A first Cr underlayer film 5 and a second Cr film formed by a sputtering method on a nonmagnetic substrate 11 made of a Ti alloy, tempered glass, or an organic resin, ceramics, or the like.
Mo base film 6, magnetic film 13, and carbon protective film 1
6 and a lubricating film 17 formed thereon.

Here, the Cr composition of the CrMo underlayer 6 is 7
At 9 at%, the magnetic film 13 is made of Co-18a having a thickness of 20 nm.
It is a t% Cr-8at% Pt alloy film. A Cr alloy and a magnetic film are grown alone on a glass substrate by about 300 nm, and X-ray diffraction measurement is performed. The Cr alloy has a lattice constant of 2.957 ° in a bcc structure, and the magnetic film has a ccp length of 4.957 in a hcp structure. It turned out to be 146 °.

The thickness of the carbon protective layer 16 was 10 nm. Further, the lubricating layer 17 is an adsorbing perfluoroalkyl ether. Also, instead of the Ni-P alloy film, W-
An amorphous alloy film such as Si may be formed by a sputtering method.

The magnetic properties for the combinations of the thicknesses of the underlayers were as follows: coercive force (FIG. 2) and squareness ratio (FIG. 3).

The material of the magnetic film is CoCrPt.
Instead of CoCrPtTa, CoCrPtTi, C
oCrFe, CoCr, CoCrIr, CoCrW, C
The same effect was obtained when oCrSmTa, CoNiZr, CoCrTa or CoNiCr was used.

(Embodiment 2) Another embodiment of the multilayer magnetic recording medium of the present invention will be described below with reference to FIG. The magnetic recording medium of the present embodiment is formed by sputtering a non-magnetic substrate 11 made of an Al-Mg alloy, a Ti alloy, a tempered glass, an organic resin, a ceramic, or the like, the surface of which is plated with a Ni-P alloy. A first Cr underlayer 5, a second CrTi underlayer 6, a magnetic film 13, and
C protective layer 16 and further a lubricating layer 17 formed thereon
It consists of.

Here, the magnetic film 13 is made of a 30 nm-thick Co
-16 at% Cr-6 at% Ta alloy layer. The thickness of the C protective layer 16 was 30 nm. Further, the lubricating layer 17 is an adsorbing perfluoroalkyl ether.

The optimum thickness of the Cr alloy film 6 is determined by the difference between the Cr film 5 and the C film.
It is determined from the magnitude relation between the lattice constants of the r alloy film 6 and the magnetic film 13. When the magnetic films 13 are the same, the smaller the lattice constant of the Cr alloy film 6, the thinner the film. However, as the difference between the lattice constants of the Cr film 5 and the Cr alloy film 6 increases, epitaxial growth becomes more difficult. If the lattice mismatch exceeds 6%, epitaxial growth does not occur. At this time, the thickness of the Cr alloy film 6 is about 1 nm. On the other hand, the Cr alloy film 6
If the thickness exceeds m, the orientation of the surface of the Cr alloy film 6 on the Cr film 5 having sufficiently developed bcc (100) orientation will be disturbed. If the lattice constant of the Cr alloy film 6 is less than 2.95 °, the Cr alloy film 6 may be 2
It is necessary to grow 0 nm or more. The composition of Cr at which the lattice constant of the Cr alloy film 6 became 2.95% was 83 at%.
When an element having a relatively large atomic radius such as W is added, the content is about 95 at%.

The c-axis length of the hcp structure of the magnetic film 13 is represented by Lm, C
When the bcc structure lattice constant of the r alloy layer 6 is Lc,
If 0.72Lm <Lc <0.79Lm, the above condition is satisfied.

The composition of the Cr alloy film 6 is, in addition to Cr, T
i, Si, Mo, V, W, Ta, Zr, Mn, Au, A
When at least one element selected from g, Pd, Cu, Ir, W, Re, and Ga is included, the lattice constant becomes larger than Cr in the bcc structure. If the same element as that contained in the magnetic film 13 is contained, epitaxial growth is likely to occur. In particular, when Ti, Si, Mo, and V are included, noise is reduced because the size of the grains is uniform.

The magnetic film 13 is an alloy having a hcp structure containing Co as a main component, and contains Cr, Pt, Pd, and Sm to become a material with high anisotropic energy. At this time, the c-axis length is
It was about 1% larger than the case without Pt, Pd and Sm. Further, Ta, Ti, Zr, Ni, Fe, Mn,
When at least one element selected from Au, Ag, Cu, Ir, W, Re, and Ga was included, the magnetostatic properties could be changed without changing the film forming conditions. Above all, T
When a and Ti are contained, the segregation of Cr is promoted and the interaction between magnetic particles is reduced, so that noise is reduced. Especially Ta
When the content is 6 at% or more, the fragmentation of the magnetic particles themselves is promoted, and the noise is reduced. To promote Cr segregation, Z
r, Au, Ag, Cu, Ir are also effective.

If the magnetic film 13 is divided into two layers by a nonmagnetic film such as Cr or C, it is possible to reduce medium noise by about 50%. In the SEM observation of the cross section, it is considered that the upper magnetic film is grown while inheriting the columnar structure of the lower magnetic film as it is, and the number of magnetic particles is substantially doubled. When the magnetic film 13 is multilayered,
The medium S / N is improved.

(Embodiment 3) Since the magnetic recording medium of the present invention has a high in-plane orientation and a high coercive force and a high squareness ratio, the medium noise can be reduced even at a high recording density, and an MR type or GMR having high reproduction sensitivity. Combined with a magnetic head of
Recording and reproduction are possible even at a high recording density of 1.5 gigabits or more per square inch.

Using four disks on which the medium shown in Example 1 or 2 was formed on both sides of the substrate, Co-Ni-Fe
Alternatively, a composite thin-film magnetic head having a Co-Ta-Zr alloy as a recording magnetic pole material and having an MR effect or a GMR effect in a reproducing portion, and a servo thin-film head using a Ni-Fe alloy as a recording / reproducing magnetic pole are used. A prototype of the combined magnetic recording device was manufactured. As shown in a plan view 4A and an AA 'sectional view 4B, the magnetic recording medium 81, the magnetic recording medium drive 82, the magnetic head 83, and the magnetic head drive 8
4, components such as a recording / reproducing signal system 85. Using this magnetic recording device, the average time until an error occurred at a flying spacing of 40 nm was determined, and it was proved that the reliability was high. Also, the magnetic recording device prototyped in this example has a low head flying height, so that the phase margin in recording and reproducing signals is widened, and the surface recording density is three times that of a conventional flying spacing 80 nm device using a medium. Thus, a small-sized and large-capacity magnetic recording device could be provided. When the track width is 2
150kBPI when reproduced with MR head of μm or less
At the above high recording density, a large-capacity magnetic recording apparatus having an S / N of 4 or more and an overwrite (O / W) characteristic of 26 dB or more was obtained. The same or better effect was obtained when reproducing with a GMR head.

[0032]

According to the present invention, a magnetic recording medium suitable for high-density recording by suppressing disturbance of bit boundaries to reduce medium noise, and an ultra-high-density recording medium of 1.5 gigabits or more per square inch using the magnetic recording medium. A magnetic recording medium compatible with a high-density, large-capacity magnetic recording device can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a layer structure of a magnetic recording medium according to the present invention.

FIG. 2 is a graph showing a correlation between the thickness of a Cr and Cr alloy layer and the coercive force of a magnetic layer in one embodiment of the present invention.

FIG. 3 is a graph showing the correlation between the thickness of the Cr and Cr alloy layers and the squareness ratio of the magnetic layer in one embodiment of the present invention.

FIG. 4 is a view showing a longitudinal sectional structure of a magnetic recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

2 Cr underlayer, 5 Cr underlayer, 11 nonmagnetic substrate, 13 magnetic film, 16 C protective layer, 17 lubricating layer, 1
8 Structure control film, 81 Magnetic recording medium, 82 Magnetic recording medium drive, 83 Magnetic head, 84 Magnetic head drive, 85 Recording / reproducing signal system.

Claims (6)

[Claims] 1. A magnetic recording medium having a base film, a magnetic film, a protective film, and a lubricating film laminated in that order on a substrate, wherein the base film has a thickness of 5 nm or more and less than 80 nm, preferably 15 nm.
As described above, the 1n layer laminated following the Cr layer of less than 50 nm
m, and less than 20 nm Cr as a main component, Ti, Si,
Mo, V, W, Ta, Zr, Mn, Au, Ag, Pd,
A magnetic recording medium comprising an alloy layer containing at least one element selected from Cu, Ir, Re, and Ga. 2. The magnetic recording medium according to claim 1, wherein the alloy layer mainly composed of Cr has a bcc structure and a lattice constant (a-axis length) of 2.95 ° or more. 3. The magnetic film according to claim 1, wherein the magnetic film is an alloy mainly composed of Co having an hcp structure and contains at least one element selected from the group consisting of Cr and (Pt, Pd, Sm).
Ti, Zr, Ni, Fe, Mn, Au, Ag, Cu, I
3. The magnetic recording medium according to claim 1, comprising at least one element selected from r, W, Re, and Ga. 4. When the c-axis length of the hcp structure of the magnetic film is Lm and the lattice constant of the bcc structure of the alloy layer mainly composed of Cr is Lc, 0.71 Lm <Lc <0.74 Lm.
3. The magnetic recording medium according to claim 1. 5. A magnetic recording medium, a magnetic recording medium driving unit,
In a magnetic recording medium used for a magnetic recording device having a magnetic head, a magnetic head driving unit, and a recording / reproducing signal processing system, the product Brδ of the residual magnetic flux density Br measured in the head running direction and the total film thickness δ of the magnetic film is obtained. 5. The magnetic recording medium according to claim 1, wherein the value is 100 Gm or less. 6. A magnetic recording medium, a magnetic recording medium driving unit,
4. A magnetic recording apparatus having a magnetic head, a magnetic head driving section, and a recording / reproducing signal processing system, wherein a magnetoresistive head or a giant magnetoresistive head is used as a reproducing magnetic head. A magnetic recording apparatus using the magnetic recording medium according to 4 or 5.