Measuring the cross-track profiles of a microtrack created by DC erasing both sides of a recorded track, the linear recording density dependence of the written track fringe width and that of the read track fringe width were successfully separated, both of which are usually observed in combination. It was clarified that when a thin-film head is used for reading, the read track fringe width increases as the linear recording density decreases, whereas it remains almost constant when an MR head with wide shielding layers is used. It was also clarified that the record head fringe width for a thin-film inductive head is less dependent on the linear recording density. The effects of several heads with different pole shapes on track edge phenomena were also evaluated, by partially DC erasing a written track from the track edge and measuring the change in the residual track output. It was found that the fringe field width of a record head changes depending on the pole shape, and the trimming of record head poles is very effective in reducing head field fringe effects.

This paper reports the thermal stability of particulate media, which include Co-Fe oxide, CrO2, and thick and thin MP tapes. By measuring the time decay of magnetization at room temperature, fluctuation fields were obtained as a function of reverse applied field. It was clarified that the fluctuation field has a constant and minimum value when the reverse applied field is equal to coercivity. Minimum fluctuation fields for the four particulate tapes were measured at several environmental temperatures ranging from -75 to +100. It was also clarified that the fluctuation field normalized by remanence coercivity increases as the environmental temperature increases for all tapes, indicating that it is a good measure of thermal stability. Activation volumes were also deduced as a function of temperature.

Particulate media composed of very small particles were studied to determine high-density recording performance and thermal stability. Studied media included metal particulate media with mean particle length of 71, 102 and 148 nm, and Ba ferrite particulate media with mean diameter of 22, 28 and 50 nm. Using a loss-term simulation program, taking into account gap-loss, spacing-loss and particle length loss, the recording capability (D20 of 265 kFRPI for MP and 290 kFRPI for Ba ferrite media) was estimated. Thermal stability was evaluated from magnetization time decay measurements. It was found that MP media with large Ku values and 71 nm particles were satisfactorily stable, and the particle volume is still large enough in respect of thermal stability. However, 22-nm Ba ferrite media were less stable, primarily because of small Ku values and particle volume. It was also clarified that positive inter-particle interaction accelerates magnetization time decay, in the presence of a large reverse field.