Modulation of PSSW resonance field affected by exchange stiffness A in Fe/NiFe/Fe multi-layer films with different Fe film thicknesses

摘要

Microwave devices, designed by the electromagnetic characteristics of spin waves, are widely used in radio frequency circuits and microwave systems, such as magnetic tunable filters, frequency multiplier, and signal-to-noise ratio enhancers. In order to manufacture these devices, it is not only the saturation magnetization (4πM_s) and ferromagnetic resonance linewidth (ΔH) that need to be regulated, but also the exchange stiffness (A). In this study, the Fe (t nm)/Ni_(81)Fe_(19) (50 nm)/Fe (t nm) multilayer films were proposed to regulate the 4πM_s, ΔH, and A, which were fabricated using electron beam evaporation, and the dynamic magnetic properties of the film were studied by ferromagnetic resonance (FMR) spectroscopy. Firstly, we obtain the 4πM_s, γ and H_a by fitting the uniform FMR mode. Then we obtain the exchange stiffness by fitting the first (p = 1) perpendicular standing spin wave (PSSW) mode. With the increasing Fe film thickness, the calculated saturation magnetization increased from 9250 to 14060Gs, FMR linewidth increased from 111.5 to 140.3Oe and the exchange stiffness decreased from 22.1 × 10~(-12) to 7.8 × 10~(-12)J/m.