Discoveries that guided the beginning of perpendicular magnetic recording

Abstract The speculations and discoveries that guided the beginning of perpendicular magnetic recording, which have never been systematically discussed before, are described in this paper. Especially, four important discoveries of perpendicular magnetization, Co–Cr film, effect of double layered medium, and complementarity law are described in detail. The studies on thin film media and recording mechanisms at short wavelengths aiming at the advancement of longitudinal magnetic recording in the 1960's lead to the realization of the new perpendicular magnetic recording through these discoveries. None of these works was on any list of research targets in the 1960's. The study of perpendicular magnetic recording has taught us that research should proceed systematically with definite targets and that it is important to have an attitude not to neglect phenomena that are different from the common sense at the time.