US 12,087,340 B2
Magnetic recording medium
Natsuki Ichise, Tokyo (JP); Minoru Yamaga, Tokyo (JP); Katsunori Maeshima, Tokyo (JP); Masaru Terakawa, Tokyo (JP); Takeshi Takahashi, Tokyo (JP); Tomoe Sato, Tokyo (JP); and Takashi Kataguchi, Tokyo (JP)
Assigned to Sony Group Corporation, Tokyo (JP)
Appl. No. 17/760,555
Filed by Sony Group Corporation, Tokyo (JP)
PCT Filed Sep. 4, 2020, PCT No. PCT/JP2020/033522
§ 371(c)(1), (2) Date Mar. 15, 2022,
PCT Pub. No. WO2021/059922, PCT Pub. Date Apr. 1, 2021.
Claims priority of application No. 2019-176117 (JP), filed on Sep. 26, 2019.
Prior Publication US 2022/0392488 A1, Dec. 8, 2022
Int. Cl. G11B 5/706 (2006.01); G11B 5/73 (2006.01)
CPC G11B 5/739 (2019.05) 8 Claims
OG exemplary drawing
 
1. A tape-shaped magnetic recording medium comprising:
a recording layer including an ε-iron oxide particle,
wherein an area ratio Rlow defined by ((an area Slow/a total area Stotal)×100) is 3.6% to 5.5%, where the total area Stotal is a total area of a switching field distribution (SFD) curve of the recording layer in a perpendicular direction, and where the area Slow is an area of the SFD curve corresponding to a low coercivity Hc component in a range from −500[Oe]≤Hc≤500[Oe],
wherein an SFD of the recording layer in the perpendicular direction is equal to or less than 1.1,
wherein a coercivity Hc of the recording layer in the perpendicular direction is equal to or greater than 3000[Oe] and equal to or less than 5000[Oe],
wherein a squareness ratio Rs of the recording layer in the perpendicular direction is equal to or greater than 70%,
wherein the magnetic recording medium includes a base layer having an average thickness of 4.2 μm or less,
wherein the base layer includes a polyester, and
wherein the ε-iron oxide particle has an average particle size of 16.4 nm or less.