Remanent head field study of single pole-type head based on micromagnetics

Abstract

The magnetization configurations within the pole tip of the single-pole-type head have been examined through a micromagnetic computer simulation based on the Landau–Lifshitz–Gilbert equation. The aspect ratio, including the effect of the exchange length (Lex), was defined as the ratio of the throat height (Th) to the write-track width (Tww) and the thickness (Tp), which is given (Th×Lex)/(Tww×Tp). It was found that the magnetization configuration and the perpendicular component of remanent head field (Hr) are strongly dominated by this aspect ratio at any value of Tww. It was also found that there is a characteristic aspect ratio at which Hr starts to decrease. These results show that decreasing the aspect ratio is an effective way to reduce the intensity of the remanent head field.

Reduction in remanent magnetization using a multi-layered single-pole writer

“…Even if H ex is 0 Oe, H rmax of a double layered PT is smaller than that of a single-layered PT. The reason is that the reduction in the exchange interaction between magnetizations prevents neighboring magnetizations from being aligned parallel as shown in our previous work [2].…”

“…This aspect ratio is expressed as follows: where T h denotes the neck height that is the length between the flare point and the air-bearing surface (ABS) of the main pole, and T p denotes the PT thickness. Then, lowering the neck height ðT h Þ; which is equal to reducing the aspect ratio, lowers the erasure because the shape anisotropy stabilizes the domain structure of the main pole [2,3]. However, it is difficult to fabricate a writer with a short T h at a narrow track width.…”

“…This erasure is due to remanent magnetization of the main pole. In a previous work [2], we showed that the erasure becomes serious as the write track width ðT ww Þ is reduced. We also showed that the aspect ratio of the pole tip (PT), including the effect of the exchange length ðL ex Þ; can describe the reduction in remanent magnetization.…”

Single-Pole/TMR Heads for 140->tex<$hboxGb/in^2$>/tex<Perpendicular Recording

“…This erasure is due to remanent magnetization of the main pole. In previous works [5]- [7], we showed that: 1) the erasure was due to domain instability in the main pole; 2) the erasure becomes serious as the pole width is reduced; and 3) lowering the throat height lowered the erasure because the shape anisotropy stabilizes the domain structure of the main pole. However, fabricating heads with a low throat height that is narrower than the pole width is difficult; both can be about 100 nm for 140-200 Gb/in recording.…”

Writer pole remanence of a tapered main pole head

“…[1][2][3][4] For a multilayer lamination head, reduction in the net magnetic volume at the pole tip decreases the write field. In the conventional structure, decreasing the aspect ratio of the pole tip and the multilayer lamination have been used to reduce the pole tip remanence.…”