Impedance of a ferromagnetic sandwich strip

• A theoretical approach for calculating the impedance of a three-layer sandwich, consisting of two metallic ferromagnetic layers separated by a non-magnetic conductive layer, is presented. The Maxwell equations for the electromagnetic field coupled with the Landau-Lifshitz equations for the magnetization dynamics are solved, which enables one to describe the system over a wide frequency range, including the ferromagnetic resonance. Two sandwich strip structures are analyzed, both having thickness much less than the width, and the width much less than the length: a closed structure with the magnetic film closing at the edges along the width, and an open structure without flux closures where all the layers have the same width. The impedance for the two structures is calculated and analyzed as a function of the physical parameters of the device and frequency. The closed structure is more efficient magnetically and exhibits a highly inductive response to much higher frequencies than the open structure. The analytical results obtained are directly applicable to practical design of GHz inductive components.

Nyckelord

magnetic-film inductors

anisotropy

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