Permeability Measurement up to 30 GHz of a Magnetically Isotropic Thin Film Using a Short-Circuited Coaxial Line

• Published in: Journal of the Magnetics Society of Japan Vol. 43; no. 5; p. 91
• Main Authors: Takeda, S, Kijima-Aoki, H, Masumoto, H, Suzuki, H
• Format: Journal Article
• Language: English; Japanese
• Published: Tokyo Japan Science and Technology Agency 01.09.2019
• Subjects: Bias; Ferromagnetic materials; Ferromagnetic resonance; Magnetic anisotropy; Magnetic permeability; Magnetic properties; Permeability; Thin films
• ISSN: 1882-2924; 1882-2932
• DOI: 10.3379/msjmag.1909R001

In this study, the high frequency permeability (μ) and ferromagnetic resonance(FMR) phenomena of a thin film with a strong perpendicular magnetic anisotropy and in-plane magnetically isotropic properties was measured using the short-circuited coaxial line technique; the analyzed sample had a toroidal shape. A field method was used for the background correction, where a strong magnetic bias field was applied and removed. However, when using a short-circuited coaxial line, the μ=1 condition cannot be achieved beyond a few ten GHz frequencies, whereas ferromagnetic resonance (denoted as FMR2) occurred because of the insufficient bias field. This resonance was compensated using the Landau-Lifshitz-Gilbert (LLG) equation, and the net μ-f properties without the bias field (denoted as FMR1) up to 30 GHz successfully extracted. Finally, a good agreement between the experimental results and the calculations based on the assumption of a magnetic multi-domain structure in FMR1 was achieved.