# US 7,465,501 B1 · High density magnetic recording media

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- Number: US 7,465,501 B1
- Document ID: US7465501B1
- Status: Granted
- Kind: B1
- Application number: 11/018,471
- Filed: 2004-12-22
- Granted: 2008-12-16
- Earliest claimed: 2004-12-22
- Assignees: Seagate Technology LLC
- Inventors: Li-Lien Lee; Michael Z. Wu; Shanghsien S. Rou
- Web page: https://patentgrep.com/patent/US7465501B1

## CPC

- 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 5/737: {Physical structure of underlayer, e.g. texture}
- G11B 5/7373: {Non-magnetic single underlayer comprising chromium}
- G11B 5/7377: {Physical structure of underlayer, e.g. texture}
- 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 longitudinal magnetic recording medium comprising at least four magnetic layers including a substrate, a CoCrTa magnetic intermediate layer on the substrate, wherein the CoCrTa magnetic intermediate layer comprises Cr<16 at % and Ta<6 at %, a first CoCrPtB magnetic layer on the CoCrTa layer, wherein the first CoCrPtB magnetic layer comprises Cr: 10-14%, Pt: 4-8 at %, B: 6-10%, a second CoCrPtB magnetic layer on the first CoCrPtB magnetic layer, and a third CoCrPtB magnetic layer on the second CoCrPtB layer, wherein the third CoCrPtB magnetic layer comprises Cr: 12-16 at %, Pt: 12-16 at %, B: 10-14 at % and has <10 at % Cr than that in the second CoCrPtB magnetic layer is disclosed.

## Claims

### Claim 1

A longitudinal magnetic recording medium comprising at least four magnetic layers comprising:
a substrate,
a CoCrTa magnetic intermediate layer on the substrate, wherein the CoCrTa magnetic intermediate layer comprises Cr<16 at % and Ta<6 at %,
a first CoCrPtB magnetic layer on the CoCrTa layer, wherein the first CoCrPtB magnetic layer comprises Cr: 10-14%, Pt: 4-8 at %, B: 6-10%,
a second CoCrPtB magnetic layer on the first CoCrPtB magnetic layer, and
a third CoCrPtB magnetic layer on the second CoCrPtB layer, wherein the third CoCrPtB magnetic layer comprises Cr: 12-16 at %, Pt: 12-16 at %, B: 10-14 at % and has <10 at % Cr than that in the second CoCrPtB magnetic layer, wherein the magnetic intermediate layer has a different composition than that of the first, second and third magnetic layers, wherein the second CoCrPtB magnetic layer comprises Cr: 22-26 at %, Pt: 11-15 at % and B: 4-8 at %.

### Claim 2 (depends on 1)

The longitudinal recording medium of claim 1, further comprising a non-magnetic HCP intermediate layer comprising Co and Cr with Cr content equal or greater than 30 at %, the non-magnetic HCP intermediate layer being located between the substrate and the CoCrTa magnetic intermediate layer.

### Claim 3 (depends on 2)

The longitudinal recording medium of claim 2, further comprising an underlayer between the non-magnetic HCP intermediate layer and the substrate.

### Claim 4 (depends on 3)

The longitudinal recording medium of claim 3, wherein the underlayer comprises a BCC and/or B2 structured material.

### Claim 5 (depends on 2)

The longitudinal recording medium of claim 2, wherein the underlayer has a structure selected from a single layer, laminated multilayers comprising a BCC and/or B2 structured material, and laminated films of BCC and B2 structured materials.

### Claim 6 (depends on 3)

The longitudinal recording medium of claim 3, further comprising a seedlayer.

### Claim 7 (depends on 2)

The longitudinal recording medium of claim 2, wherein Mrt of the CoCrTa magnetic intermediate layer and the non-magnetic HCP intermediate layer is 10-15% of the total Mrt of the longitudinal recording medium.

### Claim 8 (depends on 2)

The longitudinal recording medium of claim 2, wherein Mrt of the CoCrTa magnetic intermediate layer is 3-6% of the total Mrt of the longitudinal recording medium.

### Claim 9 (depends on 1)

The longitudinal recording medium of claim 1, wherein the third CoCrPtB magnetic layer further comprises 1-5 at % Cu.

### Claim 10

A longitudinal magnetic recording medium comprising at least four magnetic layers comprising:
a substrate,
a magnetic intermediate layer comprising CoCrTa,
a first magnetic layer comprising CoCrPtB,
a second magnetic layer comprising CoCrPtB, wherein the second magnetic layer has a different composition than that of the first magnetic layer, and
a third magnetic layer comprising CoCrPtB, wherein the third magnetic layer has a different composition than that of the first and second magnetic layers and the magnetic intermediate layer.

### Claim 11 (depends on 10)

The longitudinal magnetic recording medium of claim 10, wherein the magnetic intermediate layer comprises Cr<16 at % and Ta<6 at %.

### Claim 12 (depends on 10)

The longitudinal magnetic recording medium of claim 10, wherein the second magnetic layer comprises Cr: 22-26 at %, Pt: 11-15 at % and B: 4-8 at %.

### Claim 13 (depends on 10)

The longitudinal magnetic recording medium of claim 10, wherein the third magnetic layer comprises Cr: 12-16 at %, Pt: 12-16 at %, B: 10-14 at % and has <10 at % Cr than that in the second magnetic layer.

### Claim 14 (depends on 10)

The longitudinal magnetic recording medium of claim 10, further comprising a non-magnetic HCP intermediate layer comprising Co and Cr with Cr content equal or greater than 30 at %, the non-magnetic HCP intermediate layer being located between the substrate and the magnetic intermediate layer.

### Claim 15 (depends on 10)

The longitudinal magnetic recording medium of claim 10, further comprising an underlayer between the non-magnetic HCP intermediate layer and the substrate, wherein the underlayer comprises a BCC and/or B2 structured material.

### Claim 16 (depends on 15)

The longitudinal magnetic recording medium of claim 15, wherein the underlayer has a structure selected from a single layer, laminated multilayers comprising a BCC and/or B2 structured material, and laminated films of BCC and B2 structured materials.

### Claim 17 (depends on 14)

The longitudinal magnetic recording medium of claim 14, wherein Mrt of the CoCrTa magnetic intermediate layer and the non-magnetic HCP intermediate layer is 10-15% of the total Mrt of the longitudinal recording medium.

### Claim 18 (depends on 10)

The longitudinal recording medium of claim 10, wherein the third magnetic layer further comprises 1-5 at % Cu.