A Design Consideration for Main-Pole Shapes of Single-Pole Heads

The magnetic field distribution of a single-pole head in combination with a double-layered recording medium were analyzed by a two-dimensional finite element method. In the recording process, magnetic saturation occurs midway in the main pole, and this saturation decreases the head field strength and the sharpness. On the other hand, a large amount of magnetic flux leaks out from the middle of the main pole in reproduction. In accordance with these results, we designed a new main pole structure. As a result, the recording and readback sensitivities and the overwrite were improved. A D50 of 170 kFRPI was obtained by combining this new SPT head, with an 0.15 ¿m thick main pole, with a double-layered hard disk employing an 0.05 ¿m thick Co-Cr recording layer.