PERPENDICULAR MAGNETIC RECORDING

Perpendicular magnetic recording was investigated using a high-efficiency probe-type head and a high signal-to-noise ratio double-layer hard disk. It was found that the read output and the linear bit density sharply increased as the head-to-medium spacing decreased. Particularly, the output value reaches a level more than twice that of longitudinal recording. The sharp magnetic transition in perpendicular recording does not cause an increase in noise at high densities. Low-noise media superior to longitudinal recording media can be realized by controlling the magnetic domain structure of the underlayer. Consequently, this paper discusses the feasibility for an ultrahigh areal density of over 1.55 bits per square micron (1-Gbit/inch2).