The position-dependent vortex dynamics in the asymmetric superconducting ring

We study the position-dependence of vortex motion around asymmetric mesoscopic superconducting ring for the external current flowing from inner boundaries to outer boundaries based on time-dependent Ginzburg-Landau theory. The inner hole position can have a great impact on not only the vortex configuration but also the current-voltage (I-V) characteristics. Different from the vortex rotation in the symmetric structure, we demonstrate that vortices enter/exit from outer boundaries periodically and the formation of curved vortex channel strongly depend on the inner hole position. As the inner hole is close enough to the outer boundaries, vortices get deformed even at low applied current. Flux-flow state (i.e., slow-moving Abrikosov vortices) and phase-slip state (i.e., fast-moving vortices) coexist during a multiharmonic voltage oscillation. In this way, the vortex motion and critical current of the sample can be manipulated by the hole position. At the critical current corresponding to the abrupt jump in I-V curve, vortex motion becomes unstable and the vortices are trapped in the hole for the symmetric ring, while the vortices disappear at the outer boundaries for the asymmetric ring.