A coplanar waveguide permeameter for studying high-frequency properties of soft magnetic materials

The high-frequency relative permeability of thin permalloy films was measured in the frequency and time domain using a microwave coplanar waveguide (CPW). Frequency domain measurements using a loop permeameter were performed for comparison. The Fourier transform of the time domain measurement, and the frequency domain measurement on the CPW agree closely, both showing a higher-frequency secondary resonance peak which is not seen with the loop measurement. This resonance likely arises from the lowest-order perpendicular standing spin wave mode of the permalloy film. (C) 2004 American Institute of Physics.