# US 7,407,719 B1 · Longitudinal magnetic media having a granular magnetic layer

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- Number: US 7,407,719 B1
- Document ID: US7407719B1
- Status: Granted
- Kind: B1
- Application number: 10/829,164
- Filed: 2004-04-22
- Granted: 2008-08-05
- Earliest claimed: 2003-12-24
- Assignees: Seagate Technology LLC
- Inventors: Erol Girt; Li-Lien Lee; Samuel D. Harkness, IV
- Web page: https://patentgrep.com/patent/US7407719B1

## CPC

- G11B 5/658: {containing oxygen, e.g. molecular oxygen or magnetic oxide}
- G11B 5/737: {Physical structure of underlayer, e.g. texture}
- G11B 5/7377: {Physical structure of underlayer, e.g. texture}
- G11B 5/7379: {Seed layer, e.g. at least one non-magnetic layer is specifically adapted as a seed or seeding layer}
- 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 novel method of manufacturing a longitudinal granular oxide recording medium is disclosed. The method preferably entails obtaining a non-magnetic substrate, heating the substrate at a temperature T1 that is greater than 150° C., forming a first layer with body-centered cubic atomic structure and with a <200> preferred growth orientation, cooling the substrate to a temperature T2 and forming a second layer comprising a magnetic oxide-containing granular magnetic layer with a hexagonal close packed atomic structure and with a <11-20> preferred growth orientation. The magnetic oxide-containing granular magnetic layer contains magnetic crystal grains that are substantially isolated by an inter-granular region comprising a non-magnetic substance, wherein the non-magnetic substance is preferably an oxide-containing material.

## Claims

### Claim 1

A longitudinal granular oxide recording medium, comprising:
(a) at least one non-magnetic layer with body-centered cubic atomic structure with a (200) preferred growth orientation,
(b) at least one interlayer with hexagonal close packed atomic structure and with a <11-20> preferred growth orientation,
(c) at least one magnetic oxide-containing granular magnetic layer with hexagonal close packed atomic structure and with a <11-20> preferred growth orientation
wherein the interlayer comprises at least two layers: a first interlayer, IL1, located above first layer (a) and comprising a Co—X alloy, wherein X is selected from the group consisting of Cr, Pt, Ta, B, W, Mo, Ru, Si, Cu, Ag, Ge, Nb, Fe, Ni, Au and combinations thereof, and a second interlayer, IL2, comprising a Ru—Y alloy, wherein Y is selected from the group consisting of Rh, Ir, Cr, Re, Co, V, W, Ta, Zr, Hf, Ti, Mo, Au and combinations thereof.

### Claim 2 (depends on 1)

The longitudinal granular oxide recording medium of claim 1, wherein the first interlayer comprises at least 50 at. % of Co and the second interlayer comprises at least 50 at. % of Ru.

### Claim 3 (depends on 1)

The longitudinal granular oxide recording medium of claim 1, wherein the magnetic oxide-containing granular magnetic layer comprises magnetic crystal grains that are substantially isolated by an inter-granular region comprising a non-magnetic substance.

### Claim 4 (depends on 3)

The longitudinal granular oxide recording medium of claim 3, wherein there is substantially no diffusion of the non-magnetic substance from the magnetic crystal grains to the inter-granular region.

### Claim 5 (depends on 1)

The longitudinal granular oxide recording medium of claim 1, further comprising a substrate having a textured surface and the magnetic oxide-containing granular magnetic layer has an OR-Mrt of greater than 1.0.

### Claim 6 (depends on 1)

The longitudinal granular oxide recording medium of claim 1, wherein a full-width at half-maximum of a rocking curve of the magnetic oxide-containing granular magnetic layer in a [11-20] direction is less than 10°.

### Claim 7 (depends on 1)

The longitudinal granular oxide recording medium of claim 1, wherein a full-width at half-maximum of a rocking curve of the magnetic oxide-containing granular magnetic layer in a [11-20] direction is less than 7° and the magnetic oxide-containing granular magnetic layer has an OR-Mrt of greater than 1.4.