A new type of high-resistive soft magnetic amorphous films utilized for a very high-frequency range

A new type of high-resistivity soft magnetic amorphous alloy film with a very fine two-phase heterostructure was found in cosputtered Fe-B-C films. These amorphous films are found to have a number of superior properties in the high-frequency range (over∼10 MHz) over not only regular amorphous films, but also sendust film cores, which have already been applied to high-density recording media having high coercivity. They were found to exhibit unique isotropic soft magnetic B-H curves with high Bs (∼15 000 G), low Hc (∼0.3 Oe), and high ρ (∼400 μΩ cm), and the reduced magnetization versus reduced temperature curve was almost the same as the j=∞ curve of the Brillouin function. A very high permeability with less core loss, especially in the high-frequency range, was also experimentally observed in those amorphous films.