US4833020A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: HGST Japan Ltd
•
Filing: 1988-01-28
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Granted: 1989-05-23
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Expires: 2008-01-28
Abstract
Abstract In a magnetic recording medium including an underlayer and a magnetic layer formed sequentially on a substrate, the underlayer is composed of a composite underlayer having an at least two-layered structure, the underlayer on the side of the substrate is made of a material providing low modulation to the magnetic recording medium while the underlayer on the side of the magnetic layer is made of a material providing a high S/N ratio to the medium. This makes it possible to obtain a magnetic recording medium having low modulation and high S/N ratio.
Inventors
- 👤 Yoshihiro Shiroishi
- 👤 Sadao Hishiyama
- 👤 Hiroyuki Suzuki
- 👤 Tomoyuki Ohno
- 👤 Yoshibumi Matsuda
- 👤 Kazumasa Takagi
- 👤 Yoshio Gobara
- 👤 Norikazu Tsumita
- 👤 Masaki Ohura
- 👤 Masaaki Hayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:23
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/7368; G11B5/7369; G11B5/739; G11B5/73911; G11B5/73913; G11B5/73917; G11B5/73919; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12986; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
324 words
In a magnetic recording medium having a magnetic layer consisting of a metallic magnetic thin film formed on a non-magnetic surface of a substrate through an underlayer, the improvement wherein said underlayer is a composite underlayer having at least two non-magnetic layers consisting of an underlayer having a thickness of 50-2500 Å on the side of said substrate and an underlayer having a thickness of 100-500 Å on the side of said magnetic layer, said underlayer on the side of said substrate is made of a material providing low modulation to said magnetic recording medium and side underlayer on the side of said magnetic layer is formed on said underlayer on the side of said substrate either directly or through another underlayer and is made of a material providing a high S/N ratio to said magnetic recording medium, wherein said underlayer on the side of said substrate is made of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu or at least one oxide selected from the group consisting of aluminum oxide, silicon oxide and magnesium oxide, and said underlayer on the side of said magnetic layer is made of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir; or wherein both of said underlayers on the sides of said substrate and said magnetic layer are made of the same material which is at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu or the group consisting of Cr, Mo, W, Ru, Os, Pd, v, Nb, Hf, Rh, Pt and Ir, said underlayer on the side of said substrate is deposited under a condition providing low modulation and said underlayer on the side of said magnetic layer is deposited under the condition providing a high S/N ratio.
Claim 2
Dependent Claim
324 words
In a magnetic recording medium having a magnetic layer consisting of a metallic magnetic thin film formed on a non-magnetic surface of a substrate through an underlayer, the improvement wherein said underlayer is a composite underlayer having at least two non-magnetic layers consisting of an underlayer having a thickness of 50-2500 Å on the side of said substrate and an underlayer having a thickness of 100-500 Å on the side of said magnetic layer, said underlayer on the side of said substrate is made of a material providing low modulation to said magnetic recording medium and side underlayer on the side of said magnetic layer is formed on said underlayer on the side of said substrate either directly or through another underlayer and is made of a material providing a high S/N ratio to said magnetic recording medium, wherein said underlayer on the side of said substrate is made of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu or at least one oxide selected from the group consisting of aluminum oxide, silicon oxide and magnesium oxide, and said underlayer on the side of said magnetic layer is made of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir; or wherein both of said underlayers on the sides of said substrate and said magnetic layer are made of the same material which is at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu or the group consisting of Cr, Mo, W, Ru, Os, Pd, v, Nb, Hf, Rh, Pt and Ir, said underlayer on the side of said substrate is deposited under a condition providing low modulation and said underlayer on the side of said magnetic layer is deposited under the condition providing a high S/N ratio.
Claim 3
Dependent Claim
95 words
A magnetic recording medium according to claim 1, wherein said underlayer on the side of said substrate is made of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu or at least one oxide selected from the group consisting of aluminum oxide, silicon oxide and magnesium oxide, and said underlayer on the side of said magnetic layer is made of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir.
Claim 4
Dependent Claim
106 words
A magnetic recording medium according to claim 1, wherein both of said underlayers on the sides of said substrate and said magnetic layer are made of the same material which is at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu or the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir, said underlayer on the side of said substrate is deposited under the condition providing low modulation and said underlayer on the side of said magnetic layer is deposited under the condition providing a high S/N ratio.
Claim 5
Dependent Claim
77 words
A magnetic recording medium according to claim 2, wherein said underlayer on the side of said substrate is made of an alloy prepared by adding up to 20 at % of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt, Ir and Ta to at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu.
Claim 6
Dependent Claim
52 words
A magnetic recording medium according to claim 2, wherein said underlayer on the side of said magnetic layer is made of an alloy containing further up to 20 at % of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu.
Claim 7
Dependent Claim
51 words
A magnetic recording medium according to claim 4, wherein said underlayer on the side of said magnetic layer is made of an alloy containing up to 20 at % of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu.
Claim 8
Dependent Claim
140 words
A magnetic recording medium according to claim 3, wherein both of said underlayers on the sides of said substrate and said magnetic layer are made of an alloy prepared by adding up to 20 at % of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt, Ir and Ta to at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu; or an alloy prepared by adding up to 20 at % of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu to at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir.
Claim 9
Dependent Claim
55 words
A magnetic recording medium according to claim 2, wherein said underlayer on the side of said substrate is made of at least one selected from the group consisting of Zr, Si, Ti, Zr-, Si- and Ti-based alloy, and said underlayer on the side of said magnetic layer is made of Cr or a Cr-based alloy.
Claim 10
Dependent Claim
31 words
A magnetic recording medium according to claim 3, wherein both of said underlayers on the sides of said substrate and said magnetic layer are made of Cr or a Cr-based alloy.
Claim 11
Dependent Claim
24 words
A magnetic recording medium according to claim 1, wherein said non-magnetic substrate is a substrate produced by plating an Al alloy base by NiP.
Claim 12
Dependent Claim
19 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is made of Co or Co-based alloy.
Claim 13
Dependent Claim
67 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is made of a composition prepared by adding 0.1 to 20 at % of at least one element selected from the group consisting of Zr, Ti and Hf to a Co-Ni alloy containing 10 to 60 at % of Ni with respect to Co, on the basis of the total amount of Co and Ni.
Claim 14
Dependent Claim
67 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is made of a composition prepared by adding 3 to 12 at % of at least one element selected from the group consisting of Zr, Ti and Hf to a Co-Ni alloy containing 30 to 50 at % of Ni with respect to Co, on the basis of the total amount of Co and Ni.
Claim 15
Dependent Claim
67 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is made of a composition prepared by adding 6 to 30 wt % of at least one element selected from the group consisting of Zr, Ti and Hf to a Co-Cr alloy containing 3 to 20 at % of Cr with respect to Co, on the basis of the total amount of Co and Cr.
Claim 16
Dependent Claim
67 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is made of a composition prepared by adding 10 to 25 wt % of at least one element selected from the group consisting of Zr, Ti and Hf to a Co-Cr alloy containing 5 to 18 at % of Cr with respect to Co, on the basis of the total amount of Co and Cr.
Claim 17
Dependent Claim
23 words
A magnetic recording medium according to claim 1, wherein said underlayer on the side of said substrate is from 100 to 1,000 Å-thick.
Claim 18
Dependent Claim
24 words
A magnetic recording medium according to claim 1, wherein said underlayer on the side of said magnetic layer is from 500 to 3,000 Å-thick.
Claim 19
Dependent Claim
18 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is from 100 to 1,000 Å-thick.
Claim 20
Dependent Claim
18 words
A magnetic recording medium according to claim 1, wherein said magnetic layer is from 300 to 800 Å-thick.
Claim 21
Dependent Claim
34 words
A magnetic recording medium according to claim 1, wherein a non-magnetic coating layer which is from 100 to 1,000 Å-thick is disposed on the surface of said magnetic layer as a protective lubricant layer.
Claim 22
Dependent Claim
34 words
A magnetic recording medium according to claim 1, wherein a non-magnetic coating layer which is from 200 to 600 Å-thick is disposed on the surface of said magnetic layer as a protective lubricant layer.
Claim 23
Dependent Claim
34 words
A magnetic recording medium according to claim 1, wherein a non-magnetic intermediate layer is disposed between said underlayer on the side of said substrate and said underlayer on the side of said magnetic layer.
Claim 24
Dependent Claim
300 words
A magnetic recording medium comprising: a substrate, at least one major surface of which is a non-magnetic surface; a composite underlayer provided on said one major surface of said substrate, wherein said composite underlayer comprises a first underlayer provided on said one major surface of said substrate and a second underlayer provided over said first underlayer; and a metallic magnetic thin film provided on said composite underlayer; wherein said first underlayer is made of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu, or is made of an alloy formed by adding up to 20 at % of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt, Ir and Ta to at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu, or is made of at least one oxide selected from the group consisting of aluminum oxide, silicon oxide and magnesium oxide, has a thickness of 50-2500 Å, and provides low modulation to said magnetic recording medium; and wherein said second underlayer is made of at least one member selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir, or is made of an alloy formed by adding up to 20 at % of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu to at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir, has a thickness of 100-5000 Å, and provides a high S/N ratio to said magnetic recording medium.
Claim 25
Dependent Claim
300 words
A magnetic recording medium comprising: a substrate, at least one major surface of which is a non-magnetic surface; a composite underlayer provided on said one major surface of said substrate, wherein said composite underlayer comprises a first underlayer provided on said one major surface of said substrate and a second underlayer provided over said first underlayer; and a metallic magnetic thin film provided on said composite underlayer; wherein said first underlayer is made of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu, or is made of an alloy formed by adding up to 20 at % of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt, Ir and Ta to at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu, or is made of at least one oxide selected from the group consisting of aluminum oxide, silicon oxide and magnesium oxide, has a thickness of 50-2500 Å, and provides low modulation to said magnetic recording medium; and wherein said second underlayer is made of at least one member selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir, or is made of an alloy formed by adding up to 20 at % of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu to at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir, has a thickness of 100-5000 Å, and provides a high S/N ratio to said magnetic recording medium.
Claim 26
Dependent Claim
26 words
A magnetic recording medium according to claim 23, wherein said first underlayer has crystal axes which are substantially isotropic in a plane of said first underlayer.
Claim 27
Dependent Claim
37 words
A magnetic recording medium according to claim 23, wherein said second underlayer has a grain size of up to 1000 ° and is oriented so as to have high lattice matching with said metallic magnetic thin film.
Claim 28
Dependent Claim
295 words
A magnetic recording medium comprising: a substrate, at least one major surface of which is a non-magnetic surface; a composite underlayer provided on said one major surface of said substrate, wherein said composite underlayer comprises a first underlayer provided on said one major surface of said substrate and a second underlayer provided over said first underlayer; and a metallic magnetic thin film provided on said composite underlayer; wherein each of said first underlayer and said second underlayer are made of the same material which is at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu, or is an alloy formed by adding up to 20 at % of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt, Ir and Ta to at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu, or is at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir, or is an alloy formed by adding up to 20 at % of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu to at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir; wherein said first underlayer has a thickness of 50-2500 Å, and said second underlayer has a thickness of 100-5000 Å; and wherein said first underlayer is deposited under a condition providing low modulation and said second underlayer is deposited under a condition providing a high S/N ratio.
Claim 29
Dependent Claim
295 words
A magnetic recording medium comprising: a substrate, at least one major surface of which is a non-magnetic surface; a composite underlayer provided on said one major surface of said substrate, wherein said composite underlayer comprises a first underlayer provided on said one major surface of said substrate and a second underlayer provided over said first underlayer; and a metallic magnetic thin film provided on said composite underlayer; wherein each of said first underlayer and said second underlayer are made of the same material which is at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu, or is an alloy formed by adding up to 20 at % of at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt, Ir and Ta to at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu, or is at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir, or is an alloy formed by adding up to 20 at % of at least one element selected from the group consisting of Zr, Si, Ti, Y, Sc, Al, C, Ge, Sb and Cu to at least one element selected from the group consisting of Cr, Mo, W, Ru, Os, Pd, V, Nb, Hf, Rh, Pt and Ir; wherein said first underlayer has a thickness of 50-2500 Å, and said second underlayer has a thickness of 100-5000 Å; and wherein said first underlayer is deposited under a condition providing low modulation and said second underlayer is deposited under a condition providing a high S/N ratio.
Claim 30
Dependent Claim
26 words
A magnetic recording medium according to claim 26, wherein said first underlayer has crystal axes which are substantially isotropic in a plane of said first underlayer.
Claim 31
Dependent Claim
37 words
A magnetic recording medium according to claim 26, wherein said second underlayer has a grain size of up to 1000 Å and is oriented so as to have high lattice matching with said metallic magnetic thin film.
Claim 32
Dependent Claim
47 words
A magnetic recording medium according to claim 26, wherein each of said first and second underlayers are formed by sputtering, and wherein said first underlayer is formed at a higher film deposition rate and a lower gas pressure than that at which said second underlayer is formed.
Claim 33
Dependent Claim
54 words
A magnetic recording medium according to claim 29, wherein said first underlayer is formed by sputtering with a supplied power above 3W/cm 2 and argon gas pressure below 10 mTorr, and said second underlayer is formed by sputtering with a supplied power below 3 W/cm 2 and an argon gas pressure above 10 mTorr.
References Cited (Backward Citations)
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