Stability and Nonlinear Dynamics of Field-Driven Extended Domain Walls with Interfacial Dzyaloshinskii-Moriya Interaction
We analyze the stability and non-linear dynamics of extended domain walls (DWs) with Dzyaloshinskii-Moriya interaction (DMI) driven by an external magnetic field in the clean limit (i.e., in the absence of disorder and thermal fluctuations). We show that for moderate DMI strengths, the dynamics in both the low- and high-field regimes are accurately described by a rigid-wall Walker model that neglects flexural degrees of freedom. At intermediate fields, however, the system undergoes a transition into a non-trivial spatio-temporally chaotic regime characterized by dynamically roughened domain walls displaying single- or multi-valued profiles. The phase boundaries delimiting this regime in the magnetic field-DMI phase space are computed using a linear stability analysis based on Floquet theory applied to the extended domain wall, explicitly accounting for DMI and internal phase dynamics. Our theoretical analysis and predicted phase diagram are fully supported by numerical micromagnetic simulations solving the full Landau-Lifshitz-Gilbert equation.