Permeability of CoNbZr Amorphous Thin Films Over a Wide Frequency Range

CoNbZr amorphous films have attracted the attention of many researchers because of their high saturation magnetization, high permeability, low coercivity, and nearly zero magnetostriction. For these films to be used, one of the important magnetic properties is the behavior of the permeability over a wide frequency range. We have measured the permeability of a square-shaped magnetic film (13 mm × 55 mm) sputtered on a glass substrate from 1 MHz to 400 MHz using a stripline. Over 400 MHz, the permeability of the magnetic film was measured using a ring-shaped sample mounted in a coaxial fixture. The wall motion permeability of CoNbZr amorphous films decreases from 1 kHz to nearly zero at 1 MHz. The rotation permeability is constant to 100 MHz and ferromagnetic resonance is observed near 1 GHz.