Recording method, recording device, reproduction method, reproduction device, and high-speed response element

Patent metadata

Field	Value
Publication number	US-11315595-B2
Application number	US-202017035077-A
Country	US
Kind code	B2
Filing date	Sep 28, 2020
Priority date	Mar 29, 2018
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

The present invention provides a recording method and a recording device in which information can be easily recorded even in a magnetic recording medium using epsilon iron oxide particles having a high coercive force as a magnetic recording material. A recording device of the invention applies an external magnetic field H0 that inclines magnetization of epsilon iron oxide particles to a particle dispersion element containing epsilon iron oxide particles, and irradiates the particle dispersion element with light that excites the magnetization. Accordingly, the recording device is capable of inverting magnetization that is not capable of being inverted only by the external magnetic field, in accordance with a synergetic effect between the inclination of the magnetization and the light excitation of the magnetization.

First claim

The invention claimed is:

1. A recording method, comprising:
performing application of an external magnetic field and irradiation of pulsed laser light to a magnetic recording medium using epsilon iron oxide particles as a magnetic recording material to invert magnetization of the epsilon iron oxide particles,
wherein information is recorded in the magnetic recording medium in a multi-valued manner in which three or more multiple values can be identified corresponding to multistage magnetization states, by adjusting intensity of the pulsed laser light.

2. The recording method according to claim 1 ,
wherein the irradiation of the pulsed laser light to the magnetic recording medium is performed after the application of the external magnetic field to the magnetic recording medium.

3. The recording method according to claim 1 ,
wherein the application of the external magnetic field to the magnetic recording medium is performed after the irradiation of the pulsed laser light to the magnetic recording medium.

4. The recording method according to claim 1 ,
wherein the pulsed laser light has a wavelength within an absorption spectrum of the epsilon iron oxide particles.

5. A recording device, comprising:
a magnetic field application unit that is configured to apply an external magnetic field to a magnetic recording medium containing epsilon iron oxide particles, wherein the magnetic field application unit includes a through hole that penetrates through a thickness of a facing surface that is disposed to face a recording surface of the magnetic recording medium; and
a light irradiation unit that is configured to irradiate the magnetic recording medium with pulsed laser light, wherein the light irradiation unit irradiates the magnetic recording medium with the pulsed laser light through the through hole,
wherein magnetization of the epsilon iron oxide particles is inverted by the external magnetic field and the pulsed laser light.

6. A reproduction method, comprising:
detecting magnetization of a magnetic recording medium using epsilon iron oxide particles as a magnetic recording material, in which information is capable of being recorded in a multi-valued manner in which three or more multiple values can be identified corresponding to multistage magnetization states, by adjusting intensity of the pulsed laser light; and
reproducing information in accordance with intensity of the magnetization, on the basis of the intensity of the magnetization detected from the magnetic recording medium.

7. A reproduction device, comprising:
a detection unit that is configured to detect magnetization of a magnetic recording medium using epsilon iron oxide particles as a magnetic recording material, in which information is capable of being recorded in a multi-valued manner in which three or more multiple values can be identified corresponding to multistage magnetization states, by adjusting intensity of the pulsed laser light; and
an information reproduction unit that is configured to reproduce information in accordance with intensity of the magnetization, on the basis of the intensity of the magnetization detected from the magnetic recording medium.

8. A high-speed response element, containing:
epsilon iron oxide particles,
wherein a magnetization state responds in conformance with a timing when pulsed terahertz light is applied, wherein, in a response of the magnetization state, a magnetization in a perpendicular direction to a pulsed terahertz light irradiation surface of the high-speed response element increases or decreases.

9. A recording method, comprising:
performing application of an external magnetic field and irradiation of pulsed laser light to a magnetic recording medium using epsilon iron oxide particles as a magnetic recording material to invert magnetization of the epsilon iron oxide particles,
wherein information is recorded within 20 ns.

10. The high-speed response element according to claim 8 ,
wherein the magnetization state responds within 1 ps.

11. A recording device, comprising:
a magnetic field application unit that is configured to apply an external magnetic field to a magnetic recording medium containing epsilon iron oxide particles, wherein the magnetic field application unit includes a through hole that penetrates through a thickness of a facing surface that is disposed to face a recording surface of the magnetic recording medium; and
a light irradiation unit that is configured to irradiate the magnetic recording medium with light, wherein the light irradiation unit irradiates the magnetic recording medium with the light through the through hole,
wherein magnetization of the epsilon iron oxide particles is inverted by the external magnetic field and the light.

Assignees

• Univ Tokyo
• Univ Osaka
• Fujifilm Corp

Inventors

• Ohkoshi Shin-Ichi
• Nakajima Makoto
• Shirata Masashi
• Doshita Hiroaki

Classifications

• G11B5/70642 Primary

  iron oxides · CPC title

• G11B5/02 Primary

  Recording, reproducing, or erasing methods; Read, write or erase circuits therefor · CPC title

• H01F1/113

  in a bonding agent · CPC title

• G11B5/706

  characterised by the composition of the magnetic material · CPC title

• G11B5/012

  Recording on, or reproducing or erasing from, magnetic disks (G11B17/00, G11B19/00 take precedence) · CPC title