Observations of Bit Patterns Written by MIG Heads on a Thin-Film Disk

Abstract

Zigzag-shape transitions were studied from the viewpoint of the writing head field. The transition region of magnetization reversals in sputtered thin film media written using ferrite and MIG heads was observed by the colloid SEM method, since the transition region remains clear without any Bitter ferrofluid decoration. The head field was analyzed by a finite element method, with magnetic saturation taken into account. Use of the MIG head resulted in a shorter transition length than did the ferrite head. The sharply defined write field from the MIG head, which is based on the absence of saturation of the metal film in the gap region, yields a short transition length advantageous for high-density recording. The transition lengths recorded by both the MIG and the ferrite heads strongly depend on the field gradient, and more precisely, are proportional to (∂H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</sub> ∂X| <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Hx=Hc</sub> ) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-0.5</sup> .