High Density Recording with Single Pole Head

The feasibility of high-bit-density recording was investigated experimentally using a perpendicular magnetic recording system employing a single-pole head and a Co-Cr/Ni-Fe double-layer medium. To improve the reproducing sensitivity and resolution, the following were adopted: (a) a newly-developed high-sensitivity single-pole head; (b) a medium with a relatively thin (0.1 ¿m) Co-Cr layer and a thick (0.5 ¿m) Ni-Fe underlayer; and (c) a head-medium spacing of less than 0.03 ¿m. As a result, reproduced signals were detected at up to 680 kFRPI. The recording bit length at the highest density was of the order of the Co-Cr layer columnar grain diameter of the medium. This result proves that recording at densities approaching the intrinsic limit is possible, because the perpendicular recording method is free from recording demagnetization effects at high densities.