Oscillator based on pinned domain walls driven by direct current

The dynamics of a pinned domain wall in a thin ferromagnetic strip with high perpendicular magnetocrystalline anisotropy was examined by means of micromagnetic simulations. A preliminary analysis was carried out to describe both the cross-section dependence of the equilibrium states and the field-driven motion of a domain wall along perfect strips. Next, localized domain wall oscillations under application of direct currents in a strip with a notch were studied. This dynamical regime, and both the direct and the alternating contributions to the voltage signal induced by the pinned domain wall oscillations, were micromagnetically analyzed. Finally, a strip with several pinned domain walls was considered. Our analysis reveals that the direct contribution to the voltage signal can be linearly enhanced with the number of walls, an observation which could be useful to develop domain-wall-based nano-oscillators.