EP0184034A2 — Perpendicular magnetic recording medium and metho…

Claim 1

Independent Claim 65 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film, consisting essentially of: a) 21 to 60 atomic percent rare earth elements R wherein 70-100 atomic percent of said R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Hot Er and Yb; and b) the balance being Fe.

Claim 2

Dependent Claim 65 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film, consisting essentially of: a) 21 to 60 atomic percent rare earth elements R wherein 70-100 atomic percent of said R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Hot Er and Yb; and b) the balance being Fe.

Claim 3

Dependent Claim 87 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film consisting essentially of: a) 21 to 60 atomic percent rare earth elements R wherein 70-100 atomic percent of said R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Hot Er and Yb; and b) the balance being Fe and Co wherein Co amounts to less than 50 atomic percent of the sum of Fe and Co counted as the balance.

Claim 4

Dependent Claim 87 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film consisting essentially of: a) 21 to 60 atomic percent rare earth elements R wherein 70-100 atomic percent of said R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Hot Er and Yb; and b) the balance being Fe and Co wherein Co amounts to less than 50 atomic percent of the sum of Fe and Co counted as the balance.

Claim 5

Dependent Claim 94 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film consisting essentially of: a) 21 to 60 atomic percent rare earth elements R wherein 70-100 atomic percent of said R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Ho, Er and Yb; b) not exceeding 10 atomic percent of one or more of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sb, Ge, Sn, Si and Hf; and c) the balance being Fe.

Claim 6

Dependent Claim 94 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film consisting essentially of: a) 21 to 60 atomic percent rare earth elements R wherein 70-100 atomic percent of said R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Ho, Er and Yb; b) not exceeding 10 atomic percent of one or more of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sb, Ge, Sn, Si and Hf; and c) the balance being Fe.

Claim 7

Dependent Claim 117 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film consisting essentially of: a) 21 to 60 atomic percent rare earth elements R wherein 70-100 atomic percent of said R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Ho, Er and Yb; b) not exceeding 10 atomic percent of one or more of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sb, Ge, Sn, Si, Ti and Hf; and c) the balance being Fe and Co wherein Co amounts to less than 50 atomic percent of the sum of Fe and Co counted as the balance.

Claim 8

Dependent Claim 117 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film consisting essentially of: a) 21 to 60 atomic percent rare earth elements R wherein 70-100 atomic percent of said R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Ho, Er and Yb; b) not exceeding 10 atomic percent of one or more of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sb, Ge, Sn, Si, Ti and Hf; and c) the balance being Fe and Co wherein Co amounts to less than 50 atomic percent of the sum of Fe and Co counted as the balance.

Claim 9

Dependent Claim 134 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film expressed essentially by a formula: R x (Fe 1-y Co y ) z M k wherein, by atomic percent, x is 21-60 %, k is 0-10 %, and z is 30-79 % provided that y is zero to less than 0.5 by atomic ratio; wherein 70-100 atomic percent of the entire R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Ho, Er and Yb; and wherein said M is at least one selected from the group consisting of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sb, Ge, Sn, Si, Ti and Hf; said film comprises an oxidized layer in the surface thereof.

Claim 10

Dependent Claim 134 words

A perpendicular magnetic recording medium with perpendicular magnetic anisotropy comprising a thin film expressed essentially by a formula: R x (Fe 1-y Co y ) z M k wherein, by atomic percent, x is 21-60 %, k is 0-10 %, and z is 30-79 % provided that y is zero to less than 0.5 by atomic ratio; wherein 70-100 atomic percent of the entire R consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Ho, Er and Yb; and wherein said M is at least one selected from the group consisting of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sb, Ge, Sn, Si, Ti and Hf; said film comprises an oxidized layer in the surface thereof.

Claim 11

Dependent Claim 20 words

The recording medium as defined in any one of the preceding claims, wherein R is 31 to 60 atomic percent.

Claim 12

Dependent Claim 29 words

The recording medium as defined in any one of the claims 1 to 5, which has a perpendicular magnetic anisotropy constant Ku of at least 1 x 10 erg/cc.

Claim 13

Dependent Claim 24 words

The recording medium as defined in claim 6, which has a perpendicular magnetic anisotropy constant Ku of at least 2.5 x 10 6 erg/cc.

Claim 14

Dependent Claim 26 words

The recording medium as defined in any one of the preceding claims, which has a Kerr rotation angle |θ k | of at least 0.3 degree.

Claim 15

Dependent Claim 32 words

The recording medium as defined in claim 2 or 4, wherein Co amounts to less than 30 atomic percent of the sum of Fe and Co to be counted as the balance.

Claim 16

Dependent Claim 19 words

The recording medium as defined in claim 5, wherein y for Co is less than 0.3 by atomic ratio.

Claim 17

Dependent Claim 32 words

The recording medium as defined in any one of claims 1-4, wherein Fe or the sum of Fe and Co to be counted as the balance is at least 40 atomic percent.

Claim 18

Dependent Claim 16 words

The recording medium as defined in claim 5, wherein z is at least 40 atomic percent.

Claim 19

Dependent Claim 33 words

The recording medium as defined in any one of claims 1 to 5, which has a temperture difference of at least about 50°C between the crystallization temperature Tcry and the Curie temperature Tc.

Claim 20

Dependent Claim 17 words

The recording medium as defined in claim 14, wherein the temperature difference is at least about 200°C.

Claim 21

Dependent Claim 17 words

The recording medium as defined in any one of claims 1-5, wherein R is 33-50 atomic percent.

Claim 22

Dependent Claim 14 words

The recording medium as defined in claim 16, wherein R is 35-45 atomic percent.

Claim 23

Dependent Claim 25 words

The recording medium as defined in claim 16 or 17, wherein the perpendicular magnetic anisotropy constant Ku is at least 3.0 x 10 6 erglcc.

Claim 24

Dependent Claim 31 words

The recording medium as defined in claim 9, wherein Co amounts to at least about 8 atomic percent of the sum of Fe and Co to be counted as the balance.

Claim 25

Dependent Claim 32 words

The recording medium as defined in claim 19, wherein Co amounts to about 12 - about 27 atomic percent of the sum of Fe and Co to be counted as the balance.

Claim 26

Dependent Claim 23 words

The recording medium as defined in any one of the preceding claims, wherein the thin film is at least about 0.3 µm thick.

Claim 27

Dependent Claim 19 words

The recording medium as defined in claim 21, wherein the thin film is not thicker than about 3 µm.

Claim 28

Dependent Claim 19 words

The recording medium as defined in claim 22, wherein the thin film is at least about 0.7 µm thick.

Claim 29

Dependent Claim 18 words

The recording medium as defined in any one of the preceding claims, wherein R is Nd and/or Pr.

Claim 30

Dependent Claim 12 words

The recording medium as defined in claim 24, wherein R is Nd.

Claim 31

Dependent Claim 40 words

The recording medium as defined in any one of the preceding claims, wherein the thin film comprises a microfine-crystalline phase distributed in the amorphous matrix, said microfine-crystalline phase having an average crystal grain size of not exceeding about 10 nm.

Claim 32

Dependent Claim 14 words

The recording medium as defined in claim 8, which is a magneto-optic recording medium.

Claim 33

Independent Claim 182 words

A method of producing a perpendicular magnetic recording medium with perpendicular magnetic anisotropy on a substrate comprising the following steps of: a) maintaining a substrate at a temperature between 180°C and a temperature lower than crystallization temperatures of said material elements; and b) forming a thin film having a composition as specified below on the substrate by a metal gas deposition technique: said composition being expressed essentially by a formula: R x (Fe 1-y Co y ) z M k wherein, by atomic percent, x is 21-60 %, k is 0-10 %, and z is 30-79 % provided that y is zero to less than 0.5 by atomic ratio; wherein 70-100 atomic percent of the entire R consists of Nd and/or Pr, the balance of said R being one or more selected from the group consisting of Y, La, Ce, Sm, Gd, Tb, D y, Ho, Er and Yb; and wherein said M is at least one selected from the group consisting of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sb, Ge, Sn, Si, Ti and Hf.

Claim 34

Independent Claim 182 words

A method of producing a perpendicular magnetic recording medium with perpendicular magnetic anisotropy on a substrate comprising the following steps of: a) maintaining a substrate at a temperature between 180°C and a temperature lower than crystallization temperatures of said material elements; and b) forming a thin film having a composition as specified below on the substrate by a metal gas deposition technique: said composition being expressed essentially by a formula: R x (Fe 1-y Co y ) z M k wherein, by atomic percent, x is 21-60 %, k is 0-10 %, and z is 30-79 % provided that y is zero to less than 0.5 by atomic ratio; wherein 70-100 atomic percent of the entire R consists of Nd and/or Pr, the balance of said R being one or more selected from the group consisting of Y, La, Ce, Sm, Gd, Tb, D y, Ho, Er and Yb; and wherein said M is at least one selected from the group consisting of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sb, Ge, Sn, Si, Ti and Hf.

Claim 35

Dependent Claim 17 words

The method as defined in claim 28, wherein the substrate is maintained at a temperature of 200-300°C.

Claim 36

Dependent Claim 25 words

The method as defined in claim 28 or 29, wherein the thin film is formed to a thickness of about 0.3 to about 3 µm.

Claim 37

Independent Claim 159 words

A method of producing a perpendicular magnetic recording medium with perpendicular magnetic anisotropy on a substrate comprising the steps of: a) providing a thin film having a composition as specified below on a substrate by a metal gas deposition technique, and b) oxidizing the surface of said film to form an oxidized layer; said thin film composition being expressed essentially by a formula: wherein, by atomic percent, x is 21-60 %, k is 0-10 %, and z is 30-79 % provided that y is zero to less than 0.5 by atomic ratio; wherein 70-100 atomic percent of the entire k consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Ho, Er and Yb; and wherein said M is at least one selected from the group consisting of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sbr Ge, Sn, Si, Ti and Hf.

Claim 38

Independent Claim 159 words

A method of producing a perpendicular magnetic recording medium with perpendicular magnetic anisotropy on a substrate comprising the steps of: a) providing a thin film having a composition as specified below on a substrate by a metal gas deposition technique, and b) oxidizing the surface of said film to form an oxidized layer; said thin film composition being expressed essentially by a formula: wherein, by atomic percent, x is 21-60 %, k is 0-10 %, and z is 30-79 % provided that y is zero to less than 0.5 by atomic ratio; wherein 70-100 atomic percent of the entire k consists of Nd and/or Pr, the balance of said R being one or more of Y, La, Ce, Sm, Gd, Tb, Dy, Ho, Er and Yb; and wherein said M is at least one selected from the group consisting of Ni, Zr, Nb, V, Ta, Cr, Mo, W, Mn, Bi, Al, Pb, Sbr Ge, Sn, Si, Ti and Hf.

Claim 39

Dependent Claim 27 words

The method as defined in claim 31, wherein the oxidization is effected so as to form the oxidized layer with a thickness up to several tens nm.

Perpendicular magnetic recording medium and method of producing same

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