Narrow-track perpendicular write heads

Narrow-track perpendicular write heads are reviewed. Because of the strong magnetic interaction between the write head and double-layered medium in perpendicular recording, various types of media are also considered. Current technology is discussed to illustrate design issues; then, for areal densities beyond 1 Tb/in2, future technological requirements, including single-pole-type (SPT) heads for discrete track and bit-patterned media, are examined based on numerical simulations.