Two-track squeeze and adjacent track interference (ATI) are major barriers to increasing track density in hard disk drives (HDD). These depend on skew angles made by a magnetic head and circumferential direction on a magnetic disk. This paper describes relationships between the skew angle and the magnetic core width (MCW) which affects two-track squeeze and ATI performance. We propose a design concept of a track pitch profile at different skew angles considering MCW. Equivalent robustness of ATI performance on different skew angle conditions is obtained with the optimized track pitch.

Skew angle effects on the transition noise are analyzed in the longitudinal disk media by micromagnetic simulations at area densities from 14.3 Gb/in2 to 31.5 Gb/in2. The transition noise, including the peak, width and jitter noise, is the dominant noise in ultra-high density disk recording systems. An isotropic medium and an oriented medium, with a fixed grain size of 135 and a coercivity of 2900 Oe, are chosen for the noise analysis. The peak noise is studied by the distribution of the peak magnetization amplitude Mp in each bit. The transition a-parameter is no longer the value as given in the William-Comstock approximation. It is found that the transition noise is highly dependent on both the linear den sity and the skew angle, where the bit length and the grain size are on the same order. In both media, the medium noise increases severely when the skew angle is above 10 degrees.