Study on the Force and Potential for the Vortex Motion Around the Concave Film Edge by the Numerical Calculation

We studied the force and potential for the vortex around moat corner as an example of the concave edge of the superconducting film by the numerical calculation method. Vortex behavior is one of the significant factors that determine the characteristics of superconducting devices. In some simple cases, such as a straight line with a constant width, the potential for the vortex can be calculated analytically using the method of images. On the other hand, it is difficult to apply such method to arbitrary-shaped films, for example, constricted nanobridges, and moats in single-flux-quantum circuits. Control of the vortex motion is very important for such devices. We have been studying the vortex behavior by numerical calculation using the time-dependent Ginzburg-Landau equation. Vortex around the straight edge moved to the moat and accelerated with a trajectory vertical to the edge. On the other hand, vortex around the corner (concave edge) moved to the moat avoiding the corner. We calculated the force and potential distribution for the vortex inside the superconducting film. The force acting to the vortex was found to be smaller around the corner compared with that around the moat side. Such behavior was understood by the difference of the vortex distortion.