# US 8,465,854 B2 · Perpendicular magnetic recording media with thin soft magnetic underlayers and recording systems comprising same

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- Number: US 8,465,854 B2
- Document ID: US8465854B2
- Status: Granted
- Kind: B2
- Application number: 11/606,998
- Filed: 2006-12-01
- Published: 2008-06-05
- Granted: 2013-06-18
- Earliest claimed: 2006-12-01
- Assignees: Seagate Technology LLC
- Applicants: Li Tang; Weilu Xu; Youfeng Zheng; Shanghsien Rou; Connie Chunling Liu; Jianhua Xue; Li-Lien Lee
- Inventors: Li Tang; Weilu Xu; Youfeng Zheng; Shanghsien Rou; Connie Chunling Liu; Jianhua Xue; Li-Lien Lee
- Web page: https://patentgrep.com/patent/US8465854B2

## CPC

- G11B 5/674: {having differing macroscopic or microscopic structures, e.g. differing crystalline lattices, varying atomic structures or differing roughnesses}
- G11B 5/1278: {specially adapted for magnetisations perpendicular to the surface of the record carrier}
- G11B 5/667: including a soft magnetic layer
- 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}
- G11B 5/7368: {Non-polymeric layer under the lowermost magnetic recording layer (base layers having a non-magnetic layer under a soft magnetic layer G11B5/736; magnetic recording media substrates G11B5/739)}
- G11B 5/7373: {Non-magnetic single underlayer comprising chromium}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

A perpendicular magnetic recording medium comprises a non-magnetic substrate having a surface; and a plurality of overlying thin film layers forming a layer stack on the substrate surface, the layer stack including a magnetically hard perpendicular magnetic recording layer structure and an underlying soft magnetic underlayer (SUL), the SUL having a thickness of up to about 100 Å. Also disclosed is a data/information recording, storage, and retrieval system comprising the perpendicular magnetic recording medium and a single-pole magnetic transducer head including main and auxiliary poles positioned in spaced adjacency to an upper surface of the layer stack, the single-pole transducer head comprising a front shield adjacent the main pole.

## Claims

### Claim 1

A perpendicular magnetic recording medium, comprising:
(a) a non-magnetic substrate having a surface; and
(b) a plurality of overlying thin film layers forming a layer stack on said substrate surface, said layer stack including a magnetically hard perpendicular magnetic recording layer structure and an underlying soft magnetic underlayer (SUL),
wherein said perpendicular magnetic recording medium has only one SUL, and said SUL has a thickness up to about 100 Å.

### Claim 2 (depends on 1)

The medium as in claim 1, wherein:
said magnetically hard perpendicular magnetic recording layer structure comprises a multilayer structure.

### Claim 3 (depends on 2)

The medium as in claim 2, wherein:
said multilayer structure comprises a granular perpendicular magnetic recording layer wherein the magnetic grains are only weakly exchange coupled together, and an overlying continuous perpendicular magnetic recording layer wherein the magnetic grains are strongly exchange coupled laterally together.

### Claim 4 (depends on 3)

The medium as in claim 3, wherein:
said granular perpendicular magnetic recording layer and said continuous perpendicular magnetic recording layer are ferromagnetically coupled together to form a coupled granular-continuous (CGC) structure.

### Claim 5 (depends on 3)

The medium as in claim 3, wherein:
said granular perpendicular magnetic recording layer is from about 5 to about 30 nm thick and comprised of a Co-based alloy wherein segregation of magnetic grains occurs via formation of oxides, nitrides, or carbides at the boundaries between adjacent grains.

### Claim 6 (depends on 3)

The medium as in claim 3, wherein:
said continuous perpendicular magnetic recording layer is from about 2 to about 15 nm thick and comprised of one or more layers of a Co-based alloy.

### Claim 7 (depends on 3)

The medium as in claim 3, wherein:
said layer stack further comprises at least one interlayer between said multilayer perpendicular magnetic recording structure and said SUL.

### Claim 8 (depends on 7)

The medium as in claim 7, wherein:
said at least one interlayer comprises a Ru-containing material.

### Claim 9 (depends on 8)

The medium as in claim 8, wherein:
said Ru-containing material comprises RuX, where X is at least one of B and Cr.

### Claim 10 (depends on 1)

A perpendicular magnetic data/information recording, storage, and retrieval system, comprising a perpendicular magnetic recording medium as in claim 1 and a single-pole magnetic transducer head including main and auxiliary poles positioned in spaced adjacency to an upper surface of said layer stack, said single-pole transducer head comprising a front shield adjacent said main pole.

### Claim 11

A perpendicular magnetic recording medium, comprising:
(a) a non-magnetic substrate having a surface; and
(b) a plurality of overlying thin film layers forming a layer stack on said substrate surface, said layer stack including a magnetically hard perpendicular magnetic recording layer structure and an underlying soft magnetic underlayer (SUL),
wherein said perpendicular magnetic recording medium has only one SUL, and
said SUL has a thickness of about 40 Å to about 100 Å,
wherein the magnetically hard perpendicular magnetic recording layer structure comprises a granular perpendicular magnetic recording layer wherein the magnetic grains are exchange coupled together, and an overlying continuous perpendicular magnetic recording layer wherein the magnetic grains are exchange coupled laterally together, and the magnetic grains in the continuous perpendicular layer are more strongly exchange coupled than the magnetic grains in the granular perpendicular magnetic recording layer.

### Claim 12 (depends on 11)

The medium as in claim 11, wherein:
said granular perpendicular magnetic recording layer and said continuous perpendicular magnetic recording layer are ferromagnetically coupled together to form a coupled granular-continuous (CGC) structure.

### Claim 13 (depends on 11)

The medium as in claim 11, wherein:
said granular perpendicular magnetic recording layer is from about 5 to about 30 nm thick and comprised of a Co-based alloy wherein segregation of magnetic grains occurs via formation of oxides, nitrides, or carbides at the boundaries between adjacent grains.

### Claim 14 (depends on 11)

The medium as in claim 11, wherein:
said continuous perpendicular magnetic recording layer is from about 2 to about 15 nm thick and comprised of one or more layers of a Co-based alloy.

### Claim 15 (depends on 11)

The medium as in claim 11, wherein:
said layer stack further comprises at least one interlayer between said multilayer perpendicular magnetic recording structure and said SUL.

### Claim 16

A perpendicular magnetic recording medium, comprising:
(a) a non-magnetic substrate having a surface; and
(b) a plurality of overlying thin film layers forming a layer stack on said substrate surface, said layer stack including a magnetically hard perpendicular magnetic recording layer structure and an underlying soft magnetic underlayer (SUL),
wherein said perpendicular magnetic recording medium has only one SUL, and
said SUL has a thickness of about 40 Å to about 100 Å,
wherein said layer stack further comprises at least one Ru-containing material interlayer between said perpendicular magnetic recording layer and said SUL.

### Claim 17 (depends on 16)

The medium as in claim 16, wherein:
said Ru-containing material comprises RuX, where X is at least one of B and Cr.

### Claim 18 (depends on 16)

The medium as in claim 16, wherein:
the magnetically hard perpendicular magnetic recording layer structure comprises a granular perpendicular magnetic recording layer wherein the magnetic grains are exchange coupled together, and an overlying continuous perpendicular magnetic recording layer wherein the magnetic grains are exchange coupled laterally together, and the magnetic grains in the continuous perpendicular layer are more strongly exchange coupled than the magnetic grains in the granular perpendicular magnetic recording layer.

### Claim 19 (depends on 16)

The medium as in claim 16, wherein:
said granular perpendicular magnetic recording layer and said continuous perpendicular magnetic recording layer are ferromagnetically coupled together to form a coupled granular-continuous (CGC) structure.

### Claim 20 (depends on 16)

The medium as in claim 16, wherein:
said granular perpendicular magnetic recording layer is from about 5 to about 30 nm thick and comprised of a Co-based alloy wherein segregation of magnetic grains occurs via formation of oxides, nitrides, or carbides at the boundaries between adjacent grains.