High vacuum evaporation of ferromagnetic materials -- A new production technology for magnetic tapes

The vacuum deposition of ferromagnetic material at oblique incidence will become a major production technology for magnetic tapes for longitudinal recording applications in the future. In this paper the general formation mechanism of magnetic thin films, the field of relevant parameters and the dependance of magnetic properties on the essential parameters is discussed and demonstrated by a few examples of hysteresis loops: The resulting layout of laboratory and pilot production equipment developed so far for this application is demonstrated. For typical application examples, the material efficiency of the systems has been calculated as a function of the used incidence angle range. Also the differential increase in layer thickness as a function of incidence angle has been calculated in order to get a simple model for the formation of microcolumns.