GB2153852A - Anisotropic magnetic layer for magnetic recording media - Google Patents
Anisotropic magnetic layer for magnetic recording media Download PDFInfo
- Publication number
- GB2153852A GB2153852A GB08502154A GB8502154A GB2153852A GB 2153852 A GB2153852 A GB 2153852A GB 08502154 A GB08502154 A GB 08502154A GB 8502154 A GB8502154 A GB 8502154A GB 2153852 A GB2153852 A GB 2153852A
- Authority
- GB
- United Kingdom
- Prior art keywords
- magnetic
- phase
- magnetic layer
- recording medium
- magnetic recording
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005291 magnetic effect Effects 0.000 title claims abstract description 98
- 239000000758 substrate Substances 0.000 claims abstract description 16
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910020630 Co Ni Inorganic materials 0.000 claims abstract description 11
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 11
- 239000000956 alloy Substances 0.000 claims abstract description 11
- 239000013078 crystal Substances 0.000 claims abstract description 7
- 239000000203 mixture Substances 0.000 claims abstract description 6
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 4
- 229910052787 antimony Inorganic materials 0.000 claims description 3
- 229910052738 indium Inorganic materials 0.000 claims description 3
- 229910052745 lead Inorganic materials 0.000 claims description 3
- 229910052718 tin Inorganic materials 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- 229910002440 Co–Ni Inorganic materials 0.000 abstract description 7
- 238000005240 physical vapour deposition Methods 0.000 abstract description 2
- 239000002184 metal Substances 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 7
- 230000005294 ferromagnetic effect Effects 0.000 description 5
- 239000010409 thin film Substances 0.000 description 4
- 239000010953 base metal Substances 0.000 description 3
- 238000010894 electron beam technology Methods 0.000 description 3
- 229910002056 binary alloy Inorganic materials 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000002050 diffraction method Methods 0.000 description 2
- 229920001721 polyimide Polymers 0.000 description 2
- 238000001771 vacuum deposition Methods 0.000 description 2
- 238000007738 vacuum evaporation Methods 0.000 description 2
- 229910052797 bismuth Inorganic materials 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 229910052716 thallium Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/64—Record carriers characterised by the selection of the material comprising only the magnetic material without bonding agent
Landscapes
- Magnetic Record Carriers (AREA)
- Thin Magnetic Films (AREA)
Abstract
In a magnetic recording medium comprising a non-magnetic substrate and a magnetic layer formed by physical vapour deposition and having anisotropic magnetic characteristics along a surface of the magnetic layer formed on the non-magnetic substrate, the magnetic layer is composed of Co or Co-Ni alloy having a composition represented as Co100xNix, where x standing atomic percent of nickel, and 5 for composed of a face-centred cubic structure (f.c.c.) crystal phase and a hexagonal closed-pack structure (h.c.p.) crystal phase. The ratio of the two phases is defined as y = f.c.c. phase/(f.c.c. phase + h.c.p. phase) x 100 volume %, where x and y lie in an area on Cartesian coordinates surrounded by lines Y = 40 + 0.8x, Y = 10 + x, x = 0 and x = 50. <IMAGE>
Description
SPECIFICATION
Magnetic recording media
This invention relates to magnetic recording media, and more particularly to a so-called anisotropic magnetic recording medium having a magnetic layer of Co or Co-Ni alloy and having anistropic magnetic characteristics along a surface of the magnetic layer.
Recently, there has been extensively studied a thin film type magnetic recording medium, that is, a magnetic recording medium produced by forming a ferromagnetic thin film of, for example, Co or Co-Ni, on a non-magnetic substrate by a method such as vacuum deposition for the purpose of enabling a magnetic recording of high density to be made.
Especially, high coercive force Hc and high rectangular ratio Mr/Ms have been required in an anisotropic magnetic recording medium having a ferromagnetic thin film formed by substantially vertical vacuum deposition.
According to the present invention there is provided a magnetic recording medium comprising a non-magnetic substrate and a magnetic layer having anisotropic magnetic characteristics along a surface of said magnetic layer formed on said non-magnetic substrate, said magnetic layer being composed of Co or
Co-Ni alloy having a composition represented as Coioo.xNi where x is the atomic percentage of nickel, and also being composed of a facecentred cubic structure (f.c.c.) crystal phase and a hexagonal closed-pack structure (h.c.p.) crystal phase, the ratio of said two phases being defined as y = f.c.c. phase/(f.c.c. phase + h.c.p. phase) x 100 volume percent, wherein x and y lie in an area on Cartesian coordinates surrounded by lines y = 40 + 0.Sx, y = 10 + x, x = 0 and x = 50.
The invention will now be described by way of example with reference to the accompanying drawings, the sole figure of which is a graph showing a relation between the proportion of Ni and the proportion of f.c.c. phase in a composition of Co1oo-xNix.
In the embodiment of the present invention, a non-magnetic base metal layer, for example, of Bi, is formed on a non-magnetic substrate, and a ferromagnetic metal layer of Co or Co
Ni alloy is formed on the non-magnetic base metal layer by physical vapour deposition to form a magnetic recording medium. The magnetic recording medium so prepared has a high coercive force Hc, because a non-magnetic metal in the base metal layer is diffused into the ferromagnetic metal layer, and thereby crystalline particles in the ferromagnetic metal layer are finely fractionized. Moreover, the magnetic recording medium has anisotropic magnetic characteristics along a surface of the magnetic layer, since it is prepared by applying a vapour beam of the magnetic metal substantially perpendicularly to a surface of the substrate.
In a bulky binary alloy of Co-Ni, modification between hexagonal closed-pack structure (h.c.p.) (E) and face-centred cubic structure (f.c.c.) (a) occurs in a region of 22 to 32 atomic % Ni at room temperature. The binary alloy shows h.c.p. phase if the Ni content is not more than 22 atomic %, and shows f.c.c.
phase if the Ni content is not less than 32 atomic %. Referring to magnetic anisotrophy, the h.c.p. phase is of unaxial anisotropy, while the f.c.c. phase is of cubic anisotropy.
Anisotropy constants (uniaxial anisotropy constant Ku,; cubic anisotropy constant K,) are
Ku, = 4.3 X 106 erg/cc, and
K, = - 1.0 x 106 erg/cc, respectively. The coercive force Hc which is an important factor as a property of the magnetic recording medium is proportional to the magnitude of the anisotropy constant. In the anisotropic magnetic recording medium where the easy axis of magnetization is randomly two-dimensionally distributed, the rectangular ratio Mr/Ms is theoretrically Mr/Ms = 0.64 in the h.c.p.
phase having uniaxial anisotropy, while it is
Mr/Ms = 0.98 in the f.c.c. phase having cubic anisotropy.
We have investigated phases of Co and Co
Ni alloy in the magnetic layer by electron beam diffraction analysis, and found that change in the phases is not necessarily the same as that of the bulky Co-Ni alloy having the same composition. Although there occurs some variation in dependence upon conditions of preparation of the magnetic layer, the proportion of the f.c.c. phase tends to become large with increase in Ni content. In this manner, when both the h.c.p. phase and the f.c.c. phase exist in the magnetic layer, the magnetic characteristics are varied in the following manner, provided that the proportion of the f.c.c. phase (y) as a parameter is defined to y = amount of f.c.c. phase/(amount of h.c.p. phase + amount of f.c.c.
phase) x 100 (vol.%). The anisotropy constant of the entire magnetic thin film is decreased with increase in the value of (y), and accordingly the coercive force Hc is decreased. The rectangular ratio Mr/Ms becomes high with increase in the value of (y). A high density magnetic recording medium requires high coercive force Hc and high rectangular ratio Mr/Ms, and both the factors depend on the value of (y), that is, the proportion of the f.c.c. phase.
Accordingly, in embodiment of anisotropic magnetic recording medium having a magnetic layer of Co or Co-Ni alloy and according to the present invention, provided that the composition of the magnetic layer is represented by COioo#Nix, and the proportion of the f.c.c. phase to the h.c.p. phase is represented by y = amount of the f.c.c. phase/(amount of the h.c.p. phase + amount of the f.c.c.
phase) x 100 (vol.%), values of (x) and (y) are selected so as to exist in a region enclosed by two straight lines as represented by y = a + bx, that is to say, y = 40 + 0.8x and y = 10 + x in the range of O is less than or equal to x is less than or equal to 50, thus obtaining an anisotropic magnetic recording medium having magnetic characteristics where both the coercive force and the rectangular ratio are high and well-balanced.
A non-magnetic metal, for example, Bi which volumetrically expands on solidifying was deposited on a non-magnetic substrate, for example, polyimide film by vacuum evaporation, and subsequently a magnetic layer of Co10~-xNix (O is less than or equal to x is less than or equal to 50) was deposited on the Bi layer. The thickness of the Bi layer as a base layer was 100 angstroms, and the temperature of the substrate upon deposition was varied from 1 00do to 300o C. A crystal structure of the magnetic layer as prepared was investigated by electron beam diffraction analysis, and as a result, diffraction peaks of both the h.c.p. phase and the f.c.c. phase were observed in all of the magnetic layer. According to this observation, coexistence of both the phases was confirmed.The proportion of the f.c.c. phase to the h.c.p. phase (y), that is, y = amount of f.c.c. phase/(amount of h.c.p.
phase + amount of f.c.c. phase) x 100 (vol.%) was obtained from integral values of relative strengths of the diffraction peaks.
As a result, it became clear that when the proportion of the f.c.c. phase (y) and the proportion of Ni (x) in the magnetic layer of Co,O0-xNix were selected in a region (I) enclosed by the two straight lines as represented byy=40+0.8x and y = 10 + x in the range of O is less than or equal to x is less than or equal to 50 as shown by an oblique line in the drawings, magnetic characteristics where both the coercive force Hc and the rectangular ratio Mr/Ms in the magnetic recording medium are high and well-balanced may be obtained irrespective of the fact that the nonmagnetic layer is formed of Bi. More specifically, the coercive force Hc and the rectangular ratio Mr/Ms in the magnetic characteristics were Hc = 800 to 1300 Oe and
Mr/Ms = 0.70 to 0.94.
Example I
A Bi base layer of 100 angstroms thickness was deposited on a non-magnetic substrate of polyimide film having a thickness of 30 microns under vacuum of 10-4 Pa at a substrate temperature of 1 50 C, and subsequently, Co
Ni alloy (80 atomic % of Co; 20 atomic % of
Ni) was deposited on the Bi layer to form a magnetic layer having a thickness of 300 angstroms.
The proportion of the f.c.c. phase to the h.c.p. phase (y) in the magnetic in the magnetic layer was analyzed by electron beam diffraction to obtain y = 41%. The magnetic characteristics of the magnetic recording medium were such that the coercive force Hc was He = 1020 Oe and the rectangular ratio
Mr/Ms was Mr/Ms = 0.84. The magnetic characteristics were almost Indentical even when measurement was carried out in any directions in a surface of the magnetic layer.
Example 2
A magnetic recording medium was prepared in the same manner as in Example 1.
except that the base layer was formed of Ga and the thickness thereof was 100 angstroms.
The proportion of the f.c.c. phase to the h.c.p.
phase in the magnetic layer was analyzed to obtain y = 36%. The magnetic characteristics of the the magnetic recording medium were such that the coercive force Hc was Hc = 880
Oe and the rectangular ratio Mr/Ms was
Mr/Ms = 0.82.
Comparison 1
A magnetic recording medium was prepared in the same manner as in Example 1, except that the substrate temperature was set to 250or, and the thickness of the Bi base layer was 200 angstroms. The proportion of the f.c.c. phase to the h.c.p. phase in the magnetic layer was analyzed to obtain y = 20%. The magnetic characteristics of the magnetic recording medium were such that the coercive force He was Hc = 1050 Oe and the rectangular ratio Mr/Ms was
Mr/Ms = 0.68.
Comparison 2
A magnetic recording medium was prepared in the same manner as in Example 1, except that the substrate temperature was set to 1 40 C, and the thickness of the Bi base layer was 40 anstroms. The proportion of the f.c.c. phase to the h.c.p. phase in the magnetic layer was analyzed to obtain y = 60%.
The magnetic characteristics of the magnetic recording medium were such that the coercive force Hc was Hc = 430 Oe and the rectangular ratio Mr/Ms was Mr/Ms = 0.92.
The non-magnetic metal which volumetrically expands on solidifying as the base layer may be selected from Sb, Tl, Sn, Pb, In, Zn and alloys thereof, as well as Bi and Ga.
As will be apparent from Examples 1 and 2, when values of the proportion of Ni (x) and the proportion of f.c.c. phase (y) exist in the region (I) as shown in the drawing, a magnetic recording medium having high coercive force and high rectangular ratio may be obtained. On the contrary, in Comparisons 1 and 2, when the values of (x) and (y) are not in the region (I), either the coercive force or the rectangular ratio is low, and an anisotropic
magnetic recording medium having magnetic characteristics where both the coercive force and the rectangular ratio are high is not obtained.
Moreover, when the Ni content exceeds 50 atomic %, high coercive force is not obtained, and such a magnetic layer is not suitable for a high density magnetic recording medium.
Consequently, the substrate temperature on vacuum evaporation is preferably set to 100 to 300 C, and the material for the base layer is preferably selected from Bi, Ga, Sb, Sn, Pb,
In, Zn and alloys thereof. In addition, provided that conditions in the region (I) in the drawing are satisfied it is possible to obtain an anisotropic magnetic recording medium having satisfactory magnetic characteristics.
Claims (2)
1. A magnetic recording medium comprising a non-magnetic substrate and a magnetic layer having anisotropic magnetic characteristics along a surface of said magnetic layer formed on said non-magnetic substrate, said magnetic layer being composed of Co or Co
Ni alloy having a composition represented as Coioo.xNi where x is the atomic percentage of nickel, and also being composed of a facecentred cubic structure (f.c.c.) crystal phase and a hexagonal closed-pack structure (h.c.p.) crystal phase, the ratio of said two phases being defined as y = f.c.c. phase/(f.c.c. phase + h.c.p. phase) x 100 volume percent, wherein x and y lie in an area on Cartesian coordinates surrounded by lines y = 40 + 0.8x, y = 10 + x, x = 0 and x = 50.
2. A magnetic recording medium according to claim 1 wherein said magnetic layer contains a non-magnetic element selected from Bi, Ga, Sb, Sn, Pb, In, Zn and TI.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59015459A JPS60160015A (en) | 1984-01-31 | 1984-01-31 | Magnetic recording medium |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8502154D0 GB8502154D0 (en) | 1985-02-27 |
| GB2153852A true GB2153852A (en) | 1985-08-29 |
| GB2153852B GB2153852B (en) | 1987-04-29 |
Family
ID=11889378
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08502154A Expired GB2153852B (en) | 1984-01-31 | 1985-01-29 | Anisotropic magnetic layer for magnetic recording media |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS60160015A (en) |
| CA (1) | CA1255972A (en) |
| DE (1) | DE3503109A1 (en) |
| FR (1) | FR2558981B1 (en) |
| GB (1) | GB2153852B (en) |
| NL (1) | NL8500246A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4950555A (en) * | 1986-05-27 | 1990-08-21 | Denki Kagaku Kogyo Kabushiki Kaisha | Magnetic recording medium |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111095530B (en) * | 2017-09-15 | 2023-11-14 | 国立大学法人东京工业大学 | Method for manufacturing laminated structure of magnetic body and BiSb, magnetoresistive memory, and pure spin injection source |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1201957A (en) * | 1966-12-23 | 1970-08-12 | Commissariat Energie Atomique | Thin film having a high coercivity |
| EP0007755A1 (en) * | 1978-07-21 | 1980-02-06 | Xerox Corporation | Method for producing a magnetic recording medium and magnetic recording medium so produced |
| GB2096647A (en) * | 1981-04-14 | 1982-10-20 | Sony Corp | Magnetic recording media |
| GB2129832A (en) * | 1982-10-12 | 1984-05-23 | Sony Corp | Magnetic recording media |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4438066A (en) * | 1981-06-30 | 1984-03-20 | International Business Machines Corporation | Zero to low magnetostriction, high coercivity, polycrystalline, Co-Pt magnetic recording media |
-
1984
- 1984-01-31 JP JP59015459A patent/JPS60160015A/en active Pending
-
1985
- 1985-01-18 CA CA000472361A patent/CA1255972A/en not_active Expired
- 1985-01-29 GB GB08502154A patent/GB2153852B/en not_active Expired
- 1985-01-29 NL NL8500246A patent/NL8500246A/en not_active Application Discontinuation
- 1985-01-30 DE DE19853503109 patent/DE3503109A1/en not_active Withdrawn
- 1985-01-31 FR FR8501370A patent/FR2558981B1/en not_active Expired
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1201957A (en) * | 1966-12-23 | 1970-08-12 | Commissariat Energie Atomique | Thin film having a high coercivity |
| EP0007755A1 (en) * | 1978-07-21 | 1980-02-06 | Xerox Corporation | Method for producing a magnetic recording medium and magnetic recording medium so produced |
| GB2096647A (en) * | 1981-04-14 | 1982-10-20 | Sony Corp | Magnetic recording media |
| GB2129832A (en) * | 1982-10-12 | 1984-05-23 | Sony Corp | Magnetic recording media |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4950555A (en) * | 1986-05-27 | 1990-08-21 | Denki Kagaku Kogyo Kabushiki Kaisha | Magnetic recording medium |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2558981B1 (en) | 1988-11-25 |
| CA1255972A (en) | 1989-06-20 |
| FR2558981A1 (en) | 1985-08-02 |
| JPS60160015A (en) | 1985-08-21 |
| GB8502154D0 (en) | 1985-02-27 |
| NL8500246A (en) | 1985-08-16 |
| DE3503109A1 (en) | 1985-08-22 |
| GB2153852B (en) | 1987-04-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19960129 |