The dynamic susceptibility of arrays of narrow Permalloy stripes (9 mm × several μm × 200 nm) has been investigated using a single-coil broadband susceptibility spectrometer. Disagreement is observed between experimental results and the macroscopic Landau-Lifshitz model. This model does not take into account the dipolar interaction between magnetic stripes. We have performed micromagnetic calculations that include these dipolar interactions, and have found the resulting frequency dependence of the dynamic susceptibility in the linear regime to be in good agreement with our experimental data.
In this work, we investigate Zr substitution in Permalloy Ni 80 Fe 20 thin films in order to control the magnetic properties and then to tune the resonance frequency at lower values with high permeability levels. The structural transition from a crystalline to an amorphous phase, saturation induction, in-plane anisotropy, electrical resistivity, and frequency-dependent permeability are studied for the Zr content ranging from 0 to 17% at. The high-frequency permeability of these (Ni 80 Fe 20 ) 1 Zr films is first measured in the 0.1-3-GHz range using a permeameter. Assuming a gyroresonance mechanism, the frequency-dependence of the permeability is studied as a function of the magnetization, anisotropy field, and damping parameter deduced from ferromagnetic resonance characterizations. For a Zr concentration of 17%, a resistivity of 260 cm is obtained as well as very soft properties ( 0 5 Oe). We also show that the permeability is drastically affected by the Zr substitution with a significant shift of the resonance frequency from 600 to 300 MHz, which correlates with the decrease of the saturation induction and a very low anisotropy.
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