Impact of conducting nonmagnetic layers on the magnetization dynamics in thin-film magnetic nanostructures

摘要

Through rigorous numerical simulations with an improved finite-difference time-domain algorithm consistent with a linearized Landau-Lifshitz-Gilbert equation and Hoffmann interlayer exchange boundary conditions, we investigate theoretically broadband ferromagnetic resonance response of single-layer and bilayer magnetic film nanostructures closely contacting with nonmagnetic metal layers. We show that the nonmagnetic capping/seed layers decrease the nonuniformity of the magnetic field inside the magnetic films, which decreases the effect of dominating first higher-order standing spin-wave mode observable in broadband ferromagnetic resonance spectrometry. We also demonstrate that the conductivity of a microstrip line inducing a microwave Oersted field in the magnetic films insignificantly affects the frequency and linewidth of the resonances. However, it exerts a shielding effect on the magnetic field and thus reduces the amplitude of the resonance peaks. Finally, we argue that in experiments involving spin wave detection in insulating magnetic films via the inverse spin-Hall effect voltage, the platinum electrode should be placed away from the microstrip line. Our findings will be useful for the design and optimization of spintronic devices for spin-based data-storage and processing.