Tracking the Meissner Hole and Relaxation of Magnetization in (Ba,Rb)Fe2As2

Abstract

Abstract We investigated the unstable interface between vortices and anti-vortices in single crystals of iron-based superconductors (Ba0.67Rb0.33)Fe2As2 (Tc ∼ 37.6 K). These interfaces, also known as the Meissner hole, were captured with magneto-optical imaging in both pristine crystal and one with artificial point defects. Local excess current were observed flowing along the interface. In addition, we confirmed that the creep mode of such an interface follows the prediction of the critical state model, accompanied with a finite relaxation rate of magnetization.