Perpendicular magnetic recording with multiple antiferromagnetically coupled layers

• US 9,990,951 B2
• Filed: 05/09/2016
• Issued: 06/05/2018
• Est. Priority Date: 02/23/2016
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Lu, Bin
• Primary Examiner(s): Bernatz, Kevin M
• Application Number:
  US15/150,378
• Publication Number:
  US 20170243605A1
• Time in Patent Office: 757 Days
• Field of Search: None
• CPC Class Codes: G11B 5/66 the record carriers consisting of several layers
• CPC Class Codes: G11B 5/674 having differing macroscopic or microscopic structures, e.g. differing crystalline lattices, varying atomic structures or differing roughnesses
• CPC Class Codes: G11B 5/678 having three or more magnetic layers
• CPC Class Codes: G11B 5/855 Coating only part of a support with a magnetic layer

Abstract

Provided herein is an apparatus including a top continuous layer and a bottom continuous layer under the top continuous layer. The top continuous layer and the bottom continuous layer are antiferromagnetically coupled. A number of granular columns are under the bottom continuous layer. The number of granular columns include at least a first granular layer under the bottom continuous layer and a second granular layer also under the first granular layer. The first granular layer and the second granular layer are separated by a non-magnetic spacer. The first granular layer and the second granular layer are ferromagnetically coupled. The first granular layer is antiferromagnetically coupled to the bottom continuous layer.

Claims

1. A perpendicular magnetic recording medium comprising:

a layer stack, including a substrate;

a plurality of granular columns overlying the layer stack, wherein a granular column of the plurality of granular columns includes a plurality of magnetic layers, each magnetic layer of the plurality of magnetic layers having a different magnetic hardness from the other magnetic layers of the plurality of magnetic layers;

a first non-magnetic spacer layer overlying the plurality of granular columns;

a first continuous layer overlying the first non-magnetic spacer layer, wherein the first continuous layer is magnetic and antiferromagnetically coupled to a top surface of the plurality of granular columns;

a second non-magnetic spacer layer overlying the first continuous layer; and

a second continuous layer overlying the second non-magnetic spacer layer, wherein

the second continuous layer is magnetic and antiferromagnetically coupled to the first continuous layer, and

the second continuous layer has a lower switching field strength than the plurality of granular columns and generates a moment that is stronger than a moment generated by the first continuous layer.

2. The perpendicular magnetic recording medium of claim 1, wherein

the plurality of granular columns are parallel to each other,

the plurality of granular columns are perpendicular to the layer stack,

the plurality of granular columns have a magnetic anisotropy perpendicular to the layer stack, and

the plurality of granular columns include a multiple layer structure.

3. The perpendicular magnetic recording medium of claim 1, wherein the layer stack further includes

a soft magnetic underlayer (“

SUL”

) overlying the substrate;

a seed layer overlying the SUL, wherein the seed layer includes a face-centered cubic structure;

a first hexagonal close-packed layer overlying the seed layer;

a second hexagonal close-packed layer overlying the first hexagonal close-packed layer; and

a third hexagonal close-packed layer overlying the second hexagonal close-packed layer.

4. The perpendicular magnetic recording medium of claim 1, wherein a granular column of the plurality of granular columns includes:

a first magnetic layer;

a first break layer overlying the first magnetic layer;

a second magnetic layer overlying the first break layer;

a second break layer overlying the second magnetic layer; and

a third magnetic layer overlying the second break layer, wherein

the first magnetic layer is magnetically harder than the second magnetic layer, and

the second magnetic layer is magnetically harder than the third magnetic layer.

5. The perpendicular magnetic recording medium of claim 4, wherein

the first magnetic layer is ferromagnetically coupled to the second magnetic layer, and

the second magnetic layer is ferromagnetically coupled to the third magnetic layer.

6. The perpendicular magnetic recording medium of claim 1, wherein the first continuous layer magnetically orients in response to the second continuous layer.

7. The perpendicular magnetic recording medium of claim 1, wherein the plurality of granular columns magnetically orients in response to the first continuous layer.

8. A perpendicular magnetic recording medium comprising:

a top continuous layer;

a bottom continuous layer under the top continuous layer, wherein the top continuous layer and the bottom continuous layer are antiferromagnetically coupled;

a plurality of granular columns, wherein a granular column of the plurality of granular columns includes;

a first granular layer under the bottom continuous layer;

a second granular layer having a different magnetic hardness than the first granular layer under the first granular layer, wherein

the top continuous layer, the bottom continuous layer, and the plurality of granular columns are magnetic,

the top continuous layer generates a moment that is stronger than a moment generated by the bottom continuous layer and has a lower switching field strength than the plurality of granular columns,

the first granular layer and the second granular layer are separated by a non-magnetic spacer and are ferromagnetically coupled, and

the first granular layer is antiferromagnetically coupled to the bottom continuous layer; and

a layer stack including a substrate under the second granular layer.

9. The perpendicular magnetic recording medium of claim 8, wherein the top continuous layer, the bottom continuous layer, and the plurality of granular columns are perpendicularly magnetically oriented with respect to the substrate.

10. The perpendicular magnetic recording medium of claim 8, further comprising

a top ruthenium layer under the plurality of granular columns;

a middle ruthenium layer under the top ruthenium layer;

a bottom ruthenium layer under the middle ruthenium layer;

a seed layer under the bottom ruthenium layer;

a soft magnetic layer under the seed layer; and

the substrate under the soft magnetic layer.

11. The perpendicular magnetic recording medium of claim 8, further comprising

a first ruthenium layer between the top continuous layer and the bottom continuous layer;

and

a second ruthenium layer between the bottom continuous layer and the plurality of granular columns.

12. The perpendicular magnetic recording medium of claim 8, wherein the bottom continuous layer magnetically orients in response to the top continuous layer.

13. The perpendicular magnetic recording medium of claim 8, wherein the plurality of granular columns magnetically orient in response to the bottom continuous layer.