Properties of Ba ferrite particles for perpendicular magnetic recording media

Fine Ba ferrite particles, suitable for coated perpendicular magnetic recording media, have been prepared. The particles, about 0.08 μm in average diameter, are thin hexagonal platelets with easy magnetization axes normal to their planes. Coercivity H
c
is controllable in a wide range, without significant reduction in magnetization, by Co and Ti substitution. The measured temperature dependences of H
c
and σ
s
showed stable characteristics. Good squareness ratio was obtained from an orientation capability measurement.