Vortex-antivortex states in nanopatterned superconducting films

We model a periodic thin-film superconducting system containing two differently shaped antidots: circular and equilateral-triangular. In the absence of an external field, the system displays two stable states as a function of the applied current: (i) a vortex-free state at low current and, (ii) above some critical current, a state involving both a vortex and an antivortex pinned to the two respective pinning sites. At still higher currents, the system becomes unstable to repeated nucleation and annihilation of moving vortex-antivortex pairs. The two states have distinct inductive responses. It is noted that these properties open the possibility for these systems to be used as cryogenic circuit or memory elements.