# US 8,786,973 B2 · Thermally assisted magnetic recording medium and thermally assisted magnetic recording apparatus

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- Number: US 8,786,973 B2
- Document ID: US8786973B2
- Status: Granted
- Kind: B2
- Application number: 13/597,042
- Filed: 2012-08-28
- Published: 2013-09-26
- Granted: 2014-07-22
- Earliest claimed: 2012-03-23
- Assignees: Kabushiki Kaisha Toshiba
- Applicants: Soichi Oikawa
- Inventors: Soichi Oikawa
- Web page: https://patentgrep.com/patent/US8786973B2

## CPC

- G11B 5/1278: {specially adapted for magnetisations perpendicular to the surface of the record carrier}
- G11B 2005/0021: {Thermally assisted recording using an auxiliary energy source for heating the recording layer locally to assist the magnetization reversal}
- 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

According to one embodiment, a thermally assisted magnetic recording method performs heating at a temperature higher than the ambient temperature of the perpendicular recording medium and lower than a temperature at which a nucleation magnetic field Hn of the recording portion is 0, decreases a coercive force Hc of a recording portion by heating a perpendicular recording medium, and records magnetic information by applying a recording magnetic field from a recording magnetic pole to the recording portion having the decreased coercive force.

## Claims

### Claim 1

A thermally assisted magnetic recording method, comprising:
decreasing a coercive force Hc of a recording portion by heating a perpendicular recording medium; and
recording magnetic information by applying a recording magnetic field from a recording magnetic pole to the recording portion having the decreased coercive force,
wherein the heating is performed at a temperature higher than an ambient temperature of the perpendicular recording medium and lower than a temperature at which a nucleation magnetic field Hn of the recording portion is 0, and
wherein the perpendicular recording medium includes a magnetic recording layer with a multi-grain structure in which magnetic grains are magnetically isolated.

### Claim 2 (depends on 1)

The method according to claim 1, wherein a dimension of a heated region in a track width direction is larger than a recording track width.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the magnetic recording layer contains a CoCrPt alloy as a main component.

### Claim 4

A thermally assisted magnetic recording apparatus comprising:
a heating source configured to heat a recording portion of a perpendicular recording medium; and
a head including a recording magnetic pole configured to record magnetic information by applying a recording magnetic field to the recording portion having a coercive force Hc decreased by heating by the heating source,
wherein the heating is performed at a temperature higher than an ambient temperature of the perpendicular recording medium and lower than a temperature at which a nucleation magnetic field Hn of the recording portion is 0, and
wherein the perpendicular recording medium includes a magnetic recording layer with a multi-grain structure in which magnetic grains are magnetically isolated.

### Claim 5 (depends on 4)

The apparatus according to claim 4, wherein the magnetic recording layer contains a CoCrPt alloy as a main component.

### Claim 6 (depends on 4)

The apparatus according to claim 4, wherein the heating source is a semiconductor laser.

### Claim 7 (depends on 6)

The apparatus according to claim 6, wherein the semiconductor laser is installed closer to a leading side than the recording magnetic pole, and an exit hole opposes a surface of the magnetic recording medium.

### Claim 8 (depends on 6)

The apparatus according to claim 6, wherein a dimension of a beam of the semiconductor laser in a track width direction is larger than a recording track width.