Magnetic recording medium

Abstract

A magnetic recording medium is provided. The magnetic recording medium includes: a substrate; a perpendicular magnetic recording layer which is formed over the substrate; a first soft magnetic underlayer which is disposed between the perpendicular magnetic recording layer and the substrate; a second soft magnetic underlayer which is disposed between the first soft magnetic underlayer and the perpendicular magnetic recording layer; and an isolation layer which is disposed between the first soft magnetic underlayer and the second magnetic layer and which prevents magnetic interaction between the first soft magnetic underlayer and the second soft magnetic underlayer, wherein anisotropy field Hk of the second soft magnetic underlayer is greater than anisotropy field Hk of the first soft magnetic underlayer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawings will be provided by the Office upon request and payment of the necessary fee.

The above and other features and aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

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

FIGS. 2A and 2B are cross-sectional views illustrating the write and read operations of the perpendicular magnetic recording medium of FIG. 1;

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

FIG. 4 is a cross-sectional view of a perpendicular magnetic recording medium according to another exemplary embodiment of the present invention;

FIG. 5 is a cross-sectional view of a soft magnetic underlayer (SUL) structure that can be applied in a perpendicular magnetic recording medium, according to an exemplary embodiment of the present invention;

FIG. 6 is a graph illustrating a relationship between thickness and magnetic characteristics of an SUL formed of CoZrNb of a perpendicular magnetic recording medium;

FIG. 7A is a cross-sectional view of a soft magnetic underlayer structure that can be applied in a perpendicular magnetic recording medium, according to another exemplary embodiment of the present invention;

FIG. 7B is a graph illustrating a relationship between an applied magnetic field and the resulting magnetization of the SUL structure of FIG. 7A;

FIG. 8 illustrates SUL structure samples (a), (b), and (c) for comparing signal-to-noise ratios (SNRs) thereof;

FIGS. 9A through 9C are simulation results respectively illustrating the magnetic domain structures of the samples (a), (b), and (c) of FIG. 8; and

FIGS. 10A through 10C are simulation results respectively illustrating magnetic domain wall noises of the samples (a), (b), and (c) of FIG. 8.

Claims

1. A perpendicular magnetic recording medium comprising: a substrate;a perpendicular magnetic recording layer which is formed over the substrate;a first soft magnetic underlayer which is disposed between the perpendicular magnetic recording layer and the substrate;a second soft magnetic underlayer which is disposed between the first soft magnetic underlayer and the perpendicular magnetic recording layer; andan isolation layer which is disposed between the first soft magnetic underlayer and the second magnetic layer, and which prevents magnetic interaction between the first soft magnetic underlayer and the second soft magnetic underlayer,wherein anisotropy field Hk of the second soft magnetic underlayer is greater than anisotropy field Hk of the first soft magnetic underlayer.

2. The perpendicular magnetic recording medium of claim 1, wherein the second soft magnetic underlayer forms a Ruderman-Kittel-Kasuya-Yosida (RKKY) coupling and includes at least one stacked structure in which a pair of unit soft magnetic underlayers is stacked which has a non-magnetic spacer formed therebetween.

3. The perpendicular magnetic recording medium of claim 1, wherein the second soft magnetic underlayer is thinner than the first soft magnetic underlayer.

4. The perpendicular magnetic recording medium of claim 3, wherein the second soft magnetic underlayer has a thickness of between 1 and 12 nm, and the first soft magnetic underlayer has a thickness of 50 nm or more.

5. The perpendicular magnetic recording medium of claim 3, wherein the first soft magnetic underlayer and the second magnetic layer are formed of the same material.

6. The perpendicular magnetic recording medium of claim 2, wherein the second soft magnetic underlayer includes two unit soft magnetic underlayers and one spacer formed between the two unit soft magnetic underlayers, wherein each of the unit soft magnetic underlayers has a thickness of between 1 and 5 nm, the spacer has a thickness of 2 nm or less, and the first soft magnetic underlayer has a thickness of 50 nm or more.

7. The perpendicular magnetic recording medium of claim 3, wherein the second soft magnetic underlayer is formed of one selected from CoZrNb, CoZrTa, an FeTa alloy, and an FeCo alloy.

8. The perpendicular magnetic recording medium of claim 7, wherein the first soft magnetic underlayer is formed of one selected from a NiFe alloy, CoZrNb, CoZrTa, an FeTa alloy, and an FeCo alloy.

9. The perpendicular magnetic recording medium of claim 2, wherein the isolation layer is formed of a non-magnetic metal or a non-metallic material.

10. The perpendicular magnetic recording medium of claim 2, further comprising a magnetic domain control layer which is disposed between the first soft magnetic underlayer and the substrate.

11. The perpendicular magnetic recording medium of claim 10, wherein the second soft magnetic underlayer is thinner than the first soft magnetic underlayer.

12. The perpendicular magnetic recording medium of claim 11, wherein the second soft magnetic underlayer has a thickness of 1 to 12 nm, and the first soft magnetic underlayer has a thickness of 50 nm or more.

13. The perpendicular magnetic recording medium of claim 12, wherein the first soft magnetic underlayer and the second soft magnetic underlayer are formed of the same material.

14. The perpendicular magnetic recording medium of claim 12, wherein the second soft magnetic underlayer is formed of one selected from CoZrNb, CoZrTa, an FeTa alloy, and an FeCo alloy.

15. The perpendicular magnetic recording medium of claim 10, wherein the isolation layer is formed of a non-magnetic metal or a non-metallic material.

16. The perpendicular magnetic recording medium of claim 10, wherein the magnetic domain control layer is formed of IrMn.