Perpendicular magnetic recording medium and magnetic storage device

Abstract

A perpendicular magnetic recording medium is disclosed that is able to prevent the Wide Area Track Erasure phenomenon from occurring and is capable of high density recording. The perpendicular magnetic recording medium includes a substrate; a soft-magnetic backup stack structure including a first magnetic layer, a first non-magnetic coupling layer, and a second magnetic layer stacked on the substrate in order; an intermediate layer formed from a non-magnetic material on the soft-magnetic backup stacked structure; and a recording layer on the intermediate layer, the recording layer having an easy axis of magnetization perpendicular to the surface of the substrate. The first magnetic layer and the second magnetic layer are formed from a poly-crystal soft-magnetic material, each of the first magnetic layer and the second magnetic layer has an easy axis of magnetization in the surface thereof, and the magnetization of the first magnetic layer and the magnetization of the second magnetic layer are coupled and anti-parallel to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating an example of a perpendicular magnetic recording medium according to a first embodiment of the present invention;

FIG. 2A and FIG. 2B are plan views illustrating crystalline states and magnetizations of the poly-crystal soft magnetic layers 19 and 21 of the perpendicular magnetic recording medium 10 according to the first embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view illustrating another example of a perpendicular magnetic recording medium according to the first embodiment of the present invention;

FIG. 4 is a schematic cross-sectional view illustrating still another example of a perpendicular magnetic recording medium according to the first embodiment of the present invention;

FIG. 5 shows experimental results of X-ray diffraction on crystal orientation of the perpendicular magnetic recording medium of the present example;

FIG. 6 is a table showing properties of the perpendicular magnetic recording medium of the present example and examples for comparison 1 and 2; and

FIG. 7 is a schematic view of a principal portion of a magnetic storage device 50 according to a second embodiment of the present invention.

Claims

1. A perpendicular magnetic recording medium, comprising: a substrate;a soft-magnetic backup stack structure including a first magnetic layer, a first non-magnetic coupling layer, and a second magnetic layer stacked on the substrate in order;an intermediate layer formed from a non-magnetic material on the soft-magnetic backup stacked structure; anda recording layer on the intermediate layer, said recording layer having an easy axis of magnetization perpendicular to the surface of the substrate;whereinthe first magnetic layer and the second magnetic layer are formed from a poly-crystal soft-magnetic material, andeach of the first magnetic layer and the second magnetic layer has an easy axis of magnetization in the surface thereof, and a magnetization of the first magnetic layer and a magnetization of the second magnetic layer are coupled, the magnetizations being anti-parallel to each other.

2. The perpendicular magnetic recording medium as claimed in claim 1, wherein a magnetization of a crystal grain of the first magnetic layer is anti-parallel to a magnetization of a crystal grain of the second magnetic layer.

3. The perpendicular magnetic recording medium as claimed in claim 1, further comprising: another soft-magnetic backup stack structure disposed between the substrate and the soft-magnetic backup stack structure;whereinthe other soft-magnetic backup stack structure includes a third magnetic layer, a fourth magnetic layer stacked on the third magnetic layer, and a second non-magnetic coupling layer in between,the third magnetic layer and the fourth magnetic layer are formed from an amorphous soft-magnetic material, andeach of the third magnetic layer and the fourth magnetic layer has an easy axis of magnetization in the surface thereof, and a magnetization of the third magnetic layer and a magnetization of the fourth magnetic layer are coupled, the magnetizations being anti-parallel to each other.

4. The perpendicular magnetic recording medium as claimed in claim 3, wherein the substrate is disk-shaped,the crystal grain of the first magnetic layer and the crystal grain of the second magnetic layer are formed such that easy axes of magnetization thereof are randomly oriented, andthe crystal grain of the third magnetic layer and the crystal grain of the fourth magnetic layer are formed such that easy axes of magnetization thereof are parallel to a radial direction of the substrate.

5. The perpendicular magnetic recording medium as claimed in claim 1, further comprising: a separation layer below the soft-magnetic backup stack structure;whereinthe separation layer is formed from an amorphous non-magnetic material including at least one of Ta, Zr, Ti, C, Mo, W, Re, Os, Hf, Mg, and Pt.

6. The perpendicular magnetic recording medium as claimed in claim 1, wherein the intermediate layer has a hcp crystalline structure or a fcc crystalline structure.

7. The perpendicular magnetic recording medium as claimed in claim 6, wherein the intermediate layer is formed from a material including at least one of Ru, Pd, Pt, and a Ru-X2 alloy, where X2 represents a non-magnetic material including one of Ta, Nb, Co, Cr, Fe, Ni, Mn, O, and C.

8. The perpendicular magnetic recording medium as claimed in claim 6, wherein the intermediate layer includes a plurality of crystal grains each growing in a direction perpendicular to the surface of the substrate, andthe crystal grains are separated from each other by a plurality of interstices or immiscible phases.

9. The perpendicular magnetic recording medium as claimed in claim 8, wherein each of the crystal grains of the intermediate layer is formed from a material including at least one of Ru and a Ru-X2 alloy, where X2 represents a non-magnetic material including one of Ta, Nb, Co, Cr, Fe, Ni, Mn, and C.

10. The perpendicular magnetic recording medium as claimed in claim 1, wherein each of the first magnetic layer and the second magnetic layer in the soft-magnetic backup stack structure is formed from one of Ni, NiFe, and NiFe-X1, where X1 represents a non-magnetic material including one of Cr, Ru, Si, O, N, and SiO2.

11. The perpendicular magnetic recording medium as claimed in claim 1, wherein each of the first magnetic layer and the second magnetic layer of the soft-magnetic backup stack structure has a saturation magnetic flux density equal to or greater than 1 T.

12. The perpendicular magnetic recording medium as claimed in claim 1, wherein the first non-magnetic coupling layer of the soft-magnetic backup stack structure is formed from one of Ru, Cu, Cr, Rh, Ir, a Ru alloy, a Rh alloy, and an Ir alloy.

13. The perpendicular magnetic recording medium as claimed in claim 12, wherein the intermediate layer is formed from Ru or a Ru alloy, andthe intermediate layer is formed by growing a (0002) crystalline plane epitaxially on a (111) crystalline plane of the second magnetic layer.

14. The perpendicular magnetic recording medium as claimed in claim 1, wherein the recording layer is formed from a ferromagnetic material including one of Ni, Fe, a Ni-alloy, a Fe-alloy, Co, and an alloy with Co as a major component.

15. The perpendicular magnetic recording medium as claimed in claim 1, wherein the recording layer is a continuous film formed from a ferromagnetic material including one of Ni, Fe, a Ni-alloy, a Fe-alloy, Co, and an alloy with Co as a major component.

16. The perpendicular magnetic recording medium as claimed in claim 1, wherein the recording layer includes a plurality of magnetic particles each formed from a ferromagnetic material including one of Ni, Fe, a Ni-alloy, a Fe-alloy, Co, and an alloy with Co as a major component, andthe magnetic particles are separated from each other by a plurality of interstices or immiscible layers.

17. The perpendicular magnetic recording medium as claimed in claim 1, wherein the recording layer includes a first hard magnetic layer and a second hard magnetic layer stacked on the substrate in order,the first hard magnetic layer includes a plurality of magnetic particles each formed from an alloy with Co as a major component, and the magnetic particles in the first hard magnetic layer are separated from each other by a plurality of interstices or immiscible layers, andthe second hard magnetic layer is a continuous film formed from an alloy with Co as a major component.

18. The perpendicular magnetic recording medium as claimed in claim 14, wherein the alloy with Co as a major component includes one of CoPt, CoCrTa, CoCrPt, and CoCrPt-M, where, M represents at least one of B, Mo, Nb, Ta, W, and Cu.

19. A magnetic storage device, comprising: a recording and reproduction unit having a magnetic head; anda perpendicular magnetic recording medium;whereinthe perpendicular magnetic recording medium includesa substrate;a soft-magnetic backup stack structure including a first magnetic layer, a first non-magnetic coupling layer, and a second magnetic layer stacked on the substrate in order;an intermediate layer formed from a non-magnetic material on the soft-magnetic backup stacked structure; anda recording layer on the intermediate layer, said recording layer having an easy axis of magnetization perpendicular to the surface of the substrate;wherein the first magnetic layer and the second magnetic layer are formed from a poly-crystal soft-magnetic material, andeach of the first magnetic layer and the second magnetic layer has an easy axis of magnetization in the surface thereof, and a magnetization of the first magnetic layer and a magnetization of the second magnetic layer are coupled, the magnetizations being anti-parallel to each other.