Resonant collective dynamics of the weakly pinned soliton lattice in a monoaxial chiral helimagnet

Abstract

We study the spin dynamics of a confined chiral soliton lattice whose ends are weakly held. We demonstrate that in this case the system possesses its own resonant frequency. To study features of the resonant dynamics, we analyze the collective motion of the system driven by an oscillating magnetic field directed along the chiral axis. By using the method of collective coordinates we find analytically the resonant frequency and verify the result by numerical simulation of the spin dynamics with the aid of Landau-Lifshitz-Gilbert equations. The numerical simulation shows an appearance of the asymmetric profile of the frequency response function with increasing ac field, which is typical for a nonlinear resonance. To give an explanation of this behavior, we invoke the multiple-time-scale method and predict an emergence of hysteresis phenomena. We also demonstrate that the spin-motive force is strongly amplified by the resonant oscillations.