Recording and reproducing properties of magnetic tape by high incidence angle nucleation method

Application of the magnetic thin films prepared by the oblique incidence evaporation technique, named as "High Incidence angle Nucleation(HIN) method", to the microcassette music tapes has been investigated. To obtain the dynamic range at low frequency, it is required to increase film thickness of magnetic layer. However, the coercive force and the gradient of hysteresis curve, (dΦ/dH)
Hc
, of single layer film decrease as the film thickness increases after taking the maximum values at about 1000-1500 Å thickness. The multilayer films composed of A1 layers and Co-30%Ni layers being deposited alternately show the excellent magnetic properties. As-deposited multilayer films shows the large fluctuation in the reproduced output level which is the most difficult problem in the recording and reproducing properties of thin film medium. By polishing the film surface, it is improved and higher values of the reproduced output are obtained. These improvement are due to decrease of the spacing-loss between recording head and the magnetic film surface. The magnetic tapes prepared by the improved processes mentioned above, have the coercive force of more than 600 Oe and exhibit the recording frequency characteristics equal or more superior to those of the metal powder tape.