PERPENDICULAR MAGNETIC RECORDING MEDIUM AND MAGNETIC STORAGE DEVICE

• US 20140104724A1
• Filed: 10/16/2013
• Published: 04/17/2014
• Est. Priority Date: 10/17/2012
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: SHIROISHI, Yoshihiro, FUKUDA, Hiroshi, HIRAYAMA, Yoshiyuki, SATO, Yo
• Application Number:
  US14/055,012
• Publication Number:
  US 20140104724A1
• Time in Patent Office: Days
• US Class Current: 360/75
• CPC Class Codes: G11B 5/65 characterised by its composition G11B5/66 takes precedence
• CPC Class Codes: G11B 5/66 the record carriers consisting of several layers
• CPC Class Codes: G11B 5/672 having different compositions in a plurality of magnetic layers, e.g. layer compositions having differing elemental components or differing proportions of elements
• CPC Class Codes: G11B 5/737 Physical structure of underlayer, e.g. texture
• CPC Class Codes: G11B 5/851 Coating a support with a magnetic layer by sputtering

Abstract

Provided are a magnetic recording medium suitable for use with a microwave assisted magnetic recording head and suitable for such recording and a method for manufacturing the same. A perpendicular magnetic recording medium includes a recording layer including a plurality of magnetic layers. A magnetic layer as an uppermost layer of the recording layer includes three or more of sub-layers each having thickness of more than 0 and 1 nm or less, the sub-layers including a first sub-layer and a second sub-layer to make up a lamination unit layer, the first sub-layer including, as a major element, 50% or more of at least one type of element selected from the group consisting of Co, Fe and Ni, the second sub-layer including, as a major element, an element different from the major element of the first sub-layer. The magnetic layer as the uppermost layer includes a plurality of lamination unit layers having different composition of sub-layers at least one sub-layer among the lamination unit layers and/or a different film thickness of sub-layers at least one sub-layer among the lamination unit layers.

Claims

1. A perpendicular magnetic recording medium, comprising:

a recording layer including a plurality of magnetic layers on a substrate;

wherein

a magnetic layer as an uppermost layer of the recording layer includes three or more of sub-layers each having thickness of more than 0 and 1 nm or less, the sub-layers including a first sub-layer and a second sub-layer to make up a lamination unit layer, the first sub-layer including, as a major element, 50% or more of at least one type of element selected from the group consisting of Co, Fe and Ni, the second sub-layer including, as a major element, an element different from the major element of the first sub-layer, and the magnetic layer as the uppermost layer includes a plurality of lamination unit layers each having different composition of sub-layers or a different film thickness.

2. The perpendicular magnetic recording medium according to claim 1, wherein

a lamination unit that is the closest to a surface of the medium has highest perpendicular magnetic anisotropy field Hk in the magnetic layer as the uppermost layer.

3. The perpendicular magnetic recording medium according to claim 1, wherein

the sub-layers include at least 1 volume % or more and 35 volume % or less of a non-magnetic material including an oxide, a nitride, a carbide or a boride of at least one type of element selected from a first group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing.

4. The perpendicular magnetic recording medium according to claim 1, wherein

a set of the sub-layers include at least two types of sub-layers selected from a Co-based alloy, a Ni-based alloy and a Fe-based alloy including 50 at % or more of Co, Ni and Fe, respectively.

5. The perpendicular magnetic recording medium according to claim 1, wherein

the lamination unit of the magnetic layers includes lamination of sub-layers including (1) or (2):

(1) a thin film including at least one type of material selected from a Co-based alloy, a Ni-based alloy and a Fe-based alloy including 50 at % or more of Co, Ni and Fe, respectively; and

(2) a thin film including a material including 50% or more of at least one type of element selected from a third group consisting of Ru, Os, Rh, Ir, Pd, Pt, Ag and Au.

6. The perpendicular magnetic recording medium according to claim 1, wherein

the plurality of lamination unit layers have different compositions of sub-layers of at least one sub-layer among the lamination unit layers.

7. The perpendicular magnetic recording medium according to claim 1, wherein

the plurality of lamination unit layers have different film thicknesses of at least one sub-layer among the lamination unit layers.

8. The perpendicular magnetic recording medium according to claim 1, further comprising an underlayer in contact with a lowermost magnetic layer of the recording layer, the underlayer including 50% or more of at least one type of elements selected from a third group consisting of Ru, Os, Rh, Ir, Pd, Pt, Ag and Au, and a material of the following (1) or a material of the following (1) and a material of the following (2), and the underlayer being a (111) oriented thin film having a fcc structure:

(1) a material including 0.1 at % or more in total and 25 at % or less singly of at least one type of element selected from a second group consisting of Au, Cr, Ti, Zr, Hf, V, Nb, Ta, Ru, Os, Pd, Pt, Rh and Ir, and not included in the third group; and

(2) a material including at least 1 volume % or more and 35 volume % or less of a non-magnetic material including an oxide, a nitride, a carbide or a boride of at least one type of element selected from a first group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing.

9. The perpendicular magnetic recording medium according to claim 1, wherein

a magnetic layer at a lowermost part of the recording layer includes an oxide, a nitride, a carbide or a boride of at least one type of element selected from a first group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing, and is a thin film including a L1₁ type Co_0.5Pt_0.5-based ordered alloy or a m-D0₁₉ type Co_0.8Pt_0.2 having a degree of ordering of 0.4 or more and 0.6 or less.

10. The perpendicular magnetic recording medium according to claim 1, wherein

a magnetic layer at an intermediate part or a magnetic layer at a lowermost part of the recording layer includes a thin film having a Co-based alloy granular structure, including 1 volume % or more and 35 volume % or less of an oxide, a nitride, a carbide or a boride of at least one type of element selected from a first group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing.

11. The perpendicular magnetic recording medium according to claim 1, wherein

the plurality of magnetic layers of the recording layer each include a magnetic superlattice thin film including a set of sub-layers.

12. A magnetic storage device, comprising:

a magnetic recording medium;

a recording head including;

a recording pole to generate recording field to write information on the magnetic recording medium;

a high frequency magnetic field oscillation element disposed in the vicinity of the recording pole; and

a magnetic read element to read information from the magnetic recording medium; and

a controller that controls a recording operation by the recording pole and the high frequency magnetic field oscillation element and a reading operation by the magnetic read element, wherein

the magnetic recording medium includes a plurality of magnetic layers on a substrate, wherein a magnetic layer as an uppermost layer includes three or more of sub-layers each having thickness of more than 0 and 1 nm or less, the sub-layers including a first sub-layer and a second sub-layer to make up a lamination unit layer, the first sub-layer including, as a major element, 50% or more of at least one type of element selected from the group consisting of Co, Fe and Ni, the second sub-layer including, as a major element, an element different from the major element of the first sub-layer, and the magnetic layer as the uppermost layer includes at least two types of lamination unit layers each having different composition of sub-layers or a different film thickness of sub-layers.

13. The magnetic storage device according to claim 12, wherein

the high frequency magnetic field oscillation element includes a high-frequency magnetic field generation layer and a spin injection layer,

the high-frequency magnetic field generation layer has a height 1.5 times or more as long as a width, and

the spin injection layer includes two magnetic layers that are stacked via a non-magnetic intermediate layer so that the magnetic layers have mutually antiparallel magnetization.

14. The magnetic storage device according to claim 13, wherein

the magnetic recording medium includes:

a soft magnetic underlayer; and

a magnetic intermediate layer to control crystalline orientation disposed between the soft magnetic underlayer and recording layer including the plurality of magnetic layers.

15. The magnetic storage device according to claim 12, wherein

the high frequency magnetic field oscillation element includes a spin injection layer, a high-frequency magnetic field generation layer and an intermediate layer disposed between the spin injection layer and the high-frequency magnetic field generation layer, and

the intermediate layer has a thickness of more than 4 nm and 20 nm or less.

16. The magnetic storage device according to claim 12, wherein

the high frequency magnetic field oscillation element includes a spin injection layer having a magnetic anisotropy axis that is perpendicular to a film plane thereof, a high-frequency magnetic field generation layer having a magnetic easy plane at a film plane thereof effectively and a non-magnetic intermediate layer disposed between the spin injection layer and the high-frequency magnetic field generation layer,

the non-magnetic intermediate layer has a thickness of more than 4 nm and 20 nm or less, and

current is applied from the high-frequency magnetic field generation layer toward the spin injection layer.

17. The magnetic storage device according to claim 12, wherein

sufficient recording fails on the perpendicular magnetic recording medium only with recording field from the recording pole.

18. The magnetic storage device according to claim 12, further comprising a temperature sensor therein, wherein a value of recording current to excite the recording pole and a value of driving current of the high frequency magnetic field oscillation element are readjusted in accordance with a change in temperature environment of the device.

19. A method for manufacturing a perpendicular magnetic recording medium including a recording layer including a plurality of magnetic layers on a substrate;

wherein a magnetic layer as an uppermost layer of the recording layer includes three or more of sub-layers each having thickness of more than 0 and 1 nm or less, the sub-layers including a first sub-layer and a second sub-layer to make up a lamination unit layer, the first sub-layer including, as a major element, 50% or more of at least one type of element selected from the group consisting of Co, Fe and Ni, the second sub-layer including, as a major element, an element different from the major element of the first sub-layer, and the magnetic layer as the uppermost layer includes a plurality of lamination unit layers each having different composition of sub-layers or a different film thickness, the method comprising the steps of;

forming the first sub-layer using a first multi-sputtering target; and

forming the second sub-layer using a second multi-sputtering target,

wherein

an interval between ending time of the step to form the first sub-layer and starting time of the step to form the second sub-layer is 0.5% or longer of shorter time between film formation time of the first sub-layer and film formation time of the second sub-layer.

20. A method for manufacturing a perpendicular magnetic recording medium including a recording layer including a plurality of magnetic layers on a substrate;

wherein a magnetic layer as an uppermost layer of the recording layer includes three or more of sub-layers each having thickness of more than 0 and 1 nm or less, the sub-layers including a first sub-layer and a second sub-layer to make up a lamination unit layer, the first sub-layer including, as a major element, 50% or more of at least one type of element selected from the group consisting of Co, Fe and Ni, the second sub-layer including, as a major element, an element different from the major element of the first sub-layer, and the magnetic layer as the uppermost layer includes a plurality of lamination unit layers each having different composition of sub-layers or a different film thickness of sub-layers, the method comprising the steps of;

forming the first sub-layer by co-sputtering of a first sputtering target including the major element of the first sub-layer as a major component and a second sputtering target including a non-magnetic material including an oxide, a nitride, a carbide or a boride of at least one type of element selected from the group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing; and

forming the second sub-layer by co-sputtering of a third sputtering target including the major element of the second sub-layer as a major component and the second sputtering target,

wherein

in the step of forming the first-sub layer, film formation starting time by the second sputtering target is later than film formation starting time by the first sputtering target, and film formation ending time by the second sputtering target is earlier than film formation ending time by the first sputtering target, and

in the step of forming the second-sub layer, film formation starting time by the second sputtering target is later than film formation starting time by the third sputtering target, and film formation ending time by the second sputtering target is earlier than film formation ending time by the third sputtering target.

21. A multi-sputtering target including a non-magnetic material including an oxide, a nitride, a carbide or a boride of at least one type of element selected from the group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing, wherein the multi-sputtering target is used for film formation in combination with another multi-sputtering target including at least another one type of material.

22. A multi-sputtering target, comprising:

50 at % or more of at least one type of element selected from a third group consisting of Ru, Os, Rh, Ir, Pd, Pt, Ag and Au; and

0.1 at % or more in total and 25 at % or less singly of at least one type of element selected from a second group of additives consisting of Au, Cr, Ti, Zr, Hf, V, Nb, Ta, Ru, Os, Pd, Pt, Rh and Ir, from which an element overlapping with the element selected form the third group is excluded.

23. A multi-sputtering target, comprising:

50 at % or more of at least one type of element selected from the group consisting of Ru, Os, Rh, Ir, Pd, Pt, Ag and Au; and

at least 2 volume % or more and 10 volume % or less of a non-magnetic material including an oxide, a nitride, a carbide or a boride of an element selected from the group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing.

24. A multi-sputtering target, comprising:

50% or more of at least one type of element selected from a third group consisting of Ru, Os, Rh, Ir, Pd, Pt, Ag and Au;

0.1 at % or more in total and 25 at % or less singly of at least one type of element selected from a second group of additives consisting of Au, Cr, Ti, Zr, Hf, V, Nb, Ta, Ru, Os, Pd, Pt, Rh and Ir, from which an element overlapping with the element selected form the third group is excluded; and

at least 2 volume % or more and 10 volume % or less of a non-magnetic material including an oxide, a nitride, a carbide or a boride of an element selected from a first group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing.

25. A multi-sputtering target, comprising:

any one of Co, Ni and Fe, and 0.1 at % or more in total and 25 at % or less singly of at least one type of element selected from the group consisting of Au, Cr, Ti, Zr, Hf, V, Nb, Ta, Ru, Os, Pd, Pt, Rh and Ir.

26. A multi-sputtering target, comprising:

any one of Co, Ni and Fe, and at least 2 volume % or more and 10 volume % or less of a non-magnetic material including an oxide, a nitride, a carbide or a boride of an element selected from the group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing.

27. A multi-sputtering target, comprising:

any one of Co, Ni and Fe, and 0.1 at % or more in total and 25 at % or less singly of at least one type of element selected from the group consisting of Au, Cr, Ti, Zr, Hf, V, Nb, Ta, Ru, Os, Pd, Pt, Rh and Ir, and,

at least 2 volume % or more and 10 volume % or less of a non-magnetic material including an oxide, a nitride, a carbide or a boride of an element selected from the group consisting of Si, Ta, Ti, Zr and Hf or a mixture of the foregoing.