Vertical magnetic recording medium

Abstract

The vertical magnetic recording medium includes a first recording layer 16 having an easy magnetization axis directed vertical to a surface of the substrate 10, a second recording layer 20 formed over the first recording layer 16 and having an easy magnetization axis directed in-plane of the substrate 10 or oblique to the surface of the substrate 10, and a third recording layer 24 formed over the second recording layer 20 and having an easy magnetization axis directed vertical to the surface of the substrate 10, whereby the vertical magnetization recording medium can improve the reproduction output and can prevent the degradation of the signal quality due to the reproduction output decrease.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic sectional view of the vertical magnetic recording medium according to a first embodiment of the present invention, which shows a structure thereof.

FIGS. 2A and 2B are views showing the magnetization directions of the respective recording layers of the vertical magnetic recording medium according to the first embodiment of the present invention.

FIGS. 3 and 4 are graphs showing the relationship between the signal output from the vertical magnetic recording medium and film thickness of the exchange-coupling force control layer.

FIG. 5 is a graph showing the relationship between the signal quality of the signal output from the vertical magnetic recording medium and film thickness of the exchange coupling force control layer.

FIGS. 6 and 7 are graphs of MH loop characteristics of the third recording layer of the vertical magnetic recording medium according to the first embodiment of the present invention.

FIGS. 8 and 9 are diagrammatic sectional views of the modifications of the vertical magnetic recording medium according to the first embodiment of the present invention, which show a structure thereof.

FIG. 10 is a diagrammatic view of the magnetic recording device according to a second embodiment of the present invention, which shows a structure thereof.

Claims

1. A vertical magnetic recording medium comprising: a first recording layer formed over a substrate and having an easy magnetization axis directed vertical to a surface of the substrate;a second recording layer formed over the first recording layer and having an easy magnetization axis directed in-plane of the substrate or oblique to the surface of the substrate; anda third recording layer formed over the second recording layer and having an easy magnetization axis directed vertical to the surface of the substrate.

2. The vertical magnetic recording medium according to claim 1, wherein an angle formed by a magnetization direction of the third recording layer and a normal direction of the substrate is smaller than an angle formed by a magnetization direction of the second recording layer and the normal direction of the substrate.

3. The vertical magnetization recording medium according to claim 1, further comprising: a first exchange coupling force control layer formed between the first recording layer and the second recording layer for controlling an exchange coupling force between the first recording layer and the second recording layer.

4. The vertical magnetic recording medium according to claim 1, further comprising: an exchange coupling force control layer formed between the second recording layer and the third recording layer for controlling an exchange coupling force between the second recording layer and the third recording layer.

5. The vertical magnetic recording medium according to claim 3, further comprising: a second exchange coupling force control layer formed between the second recording layer and the third recording layer for controlling an exchange coupling force between the second recording layer and the third recording layer.

6. The vertical magnetic recording medium according to claim 1, wherein the third recording layer has less magnetic anisotropy than the first recording layer.

7. The vertical magnetic recording medium according to claim 1, wherein the first recording layer is formed of a film having crystal grains of a magnetic material magnetically isolated by a non-magnetic material, andthe third recording layer is formed of a film having a magnetic material continuously formed.

8. The vertical magnetic recording medium according to claim 1, wherein the third recording layer is formed of CoCrPt or CoCrPtB.

9. The vertical magnetic recording medium according to claim 3, wherein the first exchange coupling force control layer is formed of Ru, Cr, Rh, Ir or their alloys.

10. The vertical magnetic recording medium according to claim 4, wherein the exchange coupling force control layer is formed of Ru, Cr, Rh, Ir or their alloys.

11. The vertical magnetic recording medium according to claim 5, wherein the second exchange coupling force control layer is formed of Ru, Cr, Rh, Ir or their alloys.

12. A magnetic recording device comprising: a vertical magnetic recording medium including a first recording layer formed over a substrate and having an easy magnetization axis directed vertical to a surface of the substrate, a second recording layer formed over the first recording layer and having an easy magnetization axis directed in-plane of the substrate or oblique to the surface of the substrate, and a third recording layer formed over the second recording layer and having an easy magnetization axis directed vertical to the surface of the substrate; anda magnetic head disposed near the vertical magnetic recording medium, for recording magnetic information in a prescribed recording region of the vertical magnetic recording medium and reading magnetic information in a prescribed recording region of the vertical magnetic recording medium.