Time evolution of the vortex configuration associated with dynamic ordering detected by dc drive

Abstract

Abstract When a periodic shear force with a small amplitude dinp is applied to vortex assemblies having a random distribution, the vortices gradually self-organize to avoid future collisions and transform into an organized configuration. We showed recently that this random-organization or dynamic-ordering process can be detected from the time-evolution of voltage V(t) that increases to a steady-state voltage. We also showed from the subsequent readout experiment of V(t) using various ac amplitudes d that the transient vortex configuration during random organization is not microscopically homogeneous but consists of the disordered and organized regions. In this work, we develop an alternative readout method using a dc drive. It is found that the dc method gives the same results as obtained from the ac one, which further supports our view of the coexistence regions. It is expected that both methods will be applied complementarily to detect the vortex configuration over a wide range of disorder.