Measurement of thin film permeability by direct contact and optimization

A highly sensitive method for obtaining the permeability of magnetic film without a limitation of sample size was developed based on the electrical impedance of magnetic film in contact with a copper conductor. The permeability of a CoNbZr thin film (25×25 mm2, 4 μm thick) was evaluated in the frequency range of 10 MHz–4 GHz, the measured values roughly corresponding to those obtained by the Landau–Lifshitz–Gilbert equation. The proposed method shows promise for permeability measurement of wafer-sized samples because the method is free of size limitation.