Effects of Dzyaloshinskii-Moriya interaction on domain wall dynamics in ferromagnetic strips

Abstract

The prime objective of the thesis was to study the effects of interfacial Dzyaloshinskii-Moriya interaction (DMI) on Walker breakdown phenomenon in an ideal ferromagnetic system of uniformly magnetized domains. The system constitutes a single domain wall between the domains. The study exploited the use of GPU-accelerated micromagnetic simulation program Mumax3 to simulate a physical experiment. The simulated system included two uniformly magnetized domains separated by a Bloch wall. The domain wall was driven by an applied magnetic field. The simulation was performed for a range of DMI values by applying magnetic fields of different magnitudes. The domain wall velocity was then calculated using the domain wall position and elapsed time of the output data file obtained from the simulation. Numerical estimation of Walker breakdown velocity and Walker field was acquired from the domain wall velocity curve. The final outcome of the analysis revealed a linear dependence of Walker field and Walker breakdown on interfacial DMI. The study also suggested that DMI could influence a system differently depending on its magnitude. A system with a trace magnitude of DMI had a higher delay in the initial propagation of domain wall but a system equipped with a higher magnitude of DMI showed smaller delay in the initial stage of domain wall propagation.