Overwrite Characteristics for High Density Floppy Disks on EDG Heads

We discussed the overwrite behavior of enhanced dual gap-length (EDG) heads with various kinds of media; our results may be summarized as follows. (1) Compared with metal-in-gap (MIG) heads, EDG heads exhibit dramatically improved overwrite performance. This is because the increase in the effective recording gap length caused by magnetic saturation of the low-Bms material acts to bring the position of the overwrite "bottom" closer to the recording density used by the system. (2) The effects of the medium coercivity, head low-Bms material thickness and write current on the position of the overwrite "bottom" and the recording depth were clarified. (3) It was confirmed that changing the thickness of the low-Bms material in the EDG head has the same effect on the position of the overwrite "bottom" as changing the gap length of a conventional head. (4) In order to avoid recording demagnetization and lack of uniformity in the write field due to incomplete magnetic saturation of the low-Bms material, the latter should not be made thicker than is necessary.