Multiple Magnetic Resonance in Amorphous Co-Nb-Zr Films with Weak Perpendicular Anisotropy

The initial permeability of Co-Nb-Zr amorphous films was found to exhibit multiple resonance in a relatively low frequency range from a few MHz up to about 100 MHz. This is clearly observed when the films have a perpendicular anisotropy and it results in very fine stripe domains in the films. A calculation assuming spin wave resonance inside the domains well explains the behavior.