Direct imaging of the interaction between spin wave and transverse wall in magnetic nanostrip

Abstract

By micromagnetic simulations, the dynamical interaction between spin wave (SW) and a transverse wall (TW) in a magnetic nanostrip is studied. We find the dynamical interaction can be directly demonstrated by SW-induced TW oscillation, which can be obtained by calculating the total magnetic moment within the area of TW as a function of time. Two cases of the initial TW, in equilibrium state and in metastable state, are investigated and compared. Before SW reaches TW, the metastable TW oscillates naturally with a constant frequency, whereas the equilibrium TW does not oscillate. After SW acts on TW, both the metastable TW and the equilibrium TW will oscillate with a frequency that always equal to the frequency of the applied SW. The amplitude of the SW-induced TW oscillation for both the metastable case and the equilibrium case strongly depends on the frequency of the applied SW. Through tuning the frequency of the applied SW, we confirm that the natural oscillation of the metastable TW, which is independent of the applied SW, will not affect the amplitude of the SW-induced TW oscillation and the velocity of the TW motion in compare with those of the equilibrium TW. Interestingly, the frequency-response curves of the SW-induced TW oscillations display multiple resonance peaks. Moreover, we find the frequency-response curves of the SW-induced TW oscillation, SW reflection coefficient and TW velocity driven by SW share the same multiple-resonance property. It may suggest the SW-induced TW oscillation in the domain wall plays an important role in the SW-driven TW motion.