Measuring the Imaginary Part of the Complex Magnetic Permeability of Thin Films Using Resonant and Non-resonant Automated Measuring Systems

This paper considers resonant and non-resonant methods for measuring magnetic characteristics of Ni$_{80} Fe_{20}$ thin films with 1000 Å thickness. The imaginary part of complex magnetic permeability was measured by using resonant and nonresonant measuring cells. The resonant measuring cell included: a micro-strip line, a lumped capacitance, and an amplitude detector. The non-resonant measuring cell included a short-circuited micro-strip line. The studied sample of thin magnetic film is placed under the shortcircuited micro-strip line. The self-resonant frequency of the non-resonant measuring cell is higher than frequency of the ferromagnetic resonance (in field, equal 14 Oersteds). Ferromagnetic resonance method was used to study the change of measuring cell resonant frequency. The angular dependences of resonant frequency were achieved by the change of angle between constant magnetic field and high-frequency field of excitation, the hard axis of magnetization in thin magnetic film. The measurements were carried out using automation units. A numerical comparison of the obtained results showed that the difference between measurements does not exceed 5%.