US 12,367,904 B2
Magnetic recording medium
Minoru Yamaga, Tokyo (JP); and Futoshi Sasaki, Tokyo (JP)
Assigned to Sony Group Corporation, Tokyo (JP)
Appl. No. 18/284,420
Filed by Sony Group Corporation, Tokyo (JP)
PCT Filed Feb. 8, 2022, PCT No. PCT/JP2022/004840
§ 371(c)(1), (2) Date Sep. 27, 2023,
PCT Pub. No. WO2022/209316, PCT Pub. Date Oct. 6, 2022.
Claims priority of application No. 2021-059110 (JP), filed on Mar. 31, 2021.
Prior Publication US 2024/0170013 A1, May 23, 2024
Int. Cl. G11B 5/706 (2006.01); G11B 5/714 (2006.01); G11B 5/78 (2006.01)
CPC G11B 5/70626 (2013.01) [G11B 5/714 (2013.01); G11B 5/78 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A magnetic recording medium comprising a magnetic layer including magnetic powders,
wherein the magnetic layer includes first particles having a conductivity and second particles of which Mohs hardness is 7 or more,
wherein protrusions are formed on a surface of the magnetic layer side in accordance with the first particles and the second particles,
wherein a ratio (H1/H2) of an average height (H1) of protrusions formed in accordance with the first particles to an average height (H2) of protrusions formed in accordance with the second particles is 2.3 or less,
wherein the average height (H2) of the protrusions formed in accordance with the second particles is 7 nm or less,
wherein the average height (H1) of the protrusions formed in accordance with the first particles is 12 nm or less,
wherein the first particles include carbon particles,
wherein the second particles include alumina particles, and
wherein a number of the protrusions formed in accordance with the first particles on the surface of the magnetic layer side is 0.3 or more and 1.9 or less per unit area (μm2).