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 Ni80Fe20 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%

Advanced Characterization of FeNi-Based Films for the Development of Magnetic Field Sensors with Tailored Functional Parameters

Magnetometry and ferromagnetic resonance are used to quantitatively study magnetic anisotropy with an easy axis both in the film plane and perpendicular to it. In the study of single-layer and multilayer permalloy films, it is demonstrated that these methods make it possible not only to investigate the average field of perpendicular and in-plane anisotropy, but also to characterize their inhomogeneity. It is shown that the quantitative data from direct integral and local measurements of magnetic anisotropy are consistent with the direct and indirect estimates based on processing of the magnetization curves. The possibility of estimating the perpendicular magnetic anisotropy constant from the width of stripe domains in a film in the transcritical state is demonstrated. The average in-plane magnetic anisotropy field of permalloy films prepared by magnetron sputtering onto a Corning glass is almost unchanged with the thickness of a single-layer film. The inhomogeneity of the perpendicular anisotropy field for a 500 nm film is greater than that for a 100 nm film, and for a multilayer film with a total permalloy thickness of 500 nm, it is greater than that for a homogeneous film of the same thickness