Back to results
US 11,355,270 B2Granted
Magnetic powder, method for production thereof, and magnetic recording medium
AssigneeSony Corporation
InventorsMasaru Terakawa, Minoru Yamaga
Life of this patent
Estimating the term…
Abstract
A method for producing a magnetic powder includes performing a reduction treatment on the surface of particles including a hard magnetic material to form core-shell particles each having a shell portion including a soft magnetic material.
Claims29
A magnetic recording medium, comprising:
- a nonmagnetic support;
- and
- a magnetic layer including a magnetic powder, wherein
- the magnetic powder includes a plurality of core-shell particles,
- each core-shell particle of the plurality of core-shell particles includes:
- a core portion comprising a hard magnetic material;
- and
- a shell portion comprising a soft magnetic layer and an oxide film, wherein
- the oxide film has an average thickness Γbarrier and the soft magnetic layer has an average thickness Γsoft,
- the oxide film and the soft magnetic layer satisfy relations 0.4 nm≤Γbarrier≤11 nm and 0.1 Γsoft/Γbarrier≤10, and
- Γsoft/Γbarrier is a ratio of the average thickness Γsoft of the soft magnetic layer to the average thickness Γbarrier of the oxide film.
8 more elements
A magnetic powder, comprising:
- a plurality of core-shell particles, wherein each core-shell particle of the plurality of core-shell particles includes:
- a core portion comprising a hard magnetic material;
- and
- a shell portion comprising a soft magnetic layer and an oxide film, wherein
- the oxide film has an average thickness Γbarrier and the soft magnetic layer has an average thickness Γsoft,
- the oxide film and the soft magnetic layer satisfy relations 0.4 nm≤Γbarrier≤11 nm and 0.1≤Γsoft/Γbarrier≤10, and
- Γsoft/Γbarrier is a ratio of the average thickness Γsoft of the soft magnetic layer to the average thickness Γbarrier of the oxide film.
4 more elements
Dependencies are inferred from the claim text.