| abstract |
A magnetic recording medium having excellent running stability and a surface recording density of 4 Gbit / inch 2 or more is provided. A linear recording density of 300 kbpi or more, an areal recording density of 4 to 20 Gbpsi, a recording head of Bs ≧ 1.5T, 0.15 ≦ gap length ≦ 0.25 μm, and a reproducing head sh-sh length of 0.07-0. (1) The magnetic material contains hexagonal ferrite magnetic powder, particle volume 1000 to 4000 nm 3 , σs: 30 to 70 A · m 2 / kg, magnetization reversal volume 1000 to 12000 nm 3 , (2) Ra 0.5 to 3.0 nm, Rz 5 to 30 nm, (3) Magnetic layer thickness δ: 10 to 100 nm, (4) Vertical direction SQ: 0.4 to 0.7, Longitudinal direction SQ: 0.3 to 0.7 (5) Magnetic layer thickness fluctuation rate ≦ 15%, (6) Sdc / Sac 0.8 to 2.0, (7) Mrδ: 1 to 5 mT · μm, (8) Average particle size 0.5δ to 1.5δ (Nm) particles are contained in the magnetic layer . [Selection figure] None |