Perpendicular magnetic recording focused on the origin and its significance

The speculations and discoveries that guided the beginning of perpendicular magnetic recording are described in this paper. Four important discoveries of the existence of perpendicular magnetization, the Co-Cr film, the effect of double-layered medium, and the complementary relationship are described in detail. The studies on thin-film media and recording mechanisms at short wavelengths in the 1960s led to the realization of the new perpendicular magnetic recording through these discoveries. None of this work was on any list of research goals in the 1960s. The historical view of the development of magnetic recording is also discussed. It was deduced that an invention needs more than 20 years before its worldwide application and that major technological innovations take place with a period of about 40 years.