Permeability Measurement of Soft Magnetic Films at High Frequency and Multilayering Effect.

This paper reports a new permeability measurement method at high frequencies (1 MHz∼1 GHz). An inductance-line with M/C/M structure was used to estimate permeability. The inductance-line made it possible to measure frequency characteristics of permeability up to GHz because of low straycapacitance and high resonance frequency. The magnetic film pattern was designed to ignore demagnetizing field, and permeability was estimated analyzing a magnetic circuit. With this method, the NiFe/SiO2 and (Fe/SiO2)/SiO2 multilayer films were confirmed to show superior frequency characteristics by a factor of 20 to NiFe single layer film. Also, ferromagnetic resonance (FMR) was observed in these multilayer films at 650 and 750 MHz.