Creation and pinning of vortex-antivortex pairs

Abstract

Computer modeling is reported about the creation and pinning of a magnetic vortex-antivortex (V-AV) pair in a superconducting thin film, due to the magnetic field of a vertical magnetic dipole above the film, and two antidot pins inside the film. For film thickness $= 0.1ξ$, $κ= 2$, and no pins, we find the film carries two V-AV pairs at steady state in the imposed flux range $2.10Φ_0 < Φ^+ < 3.0Φ_0$, and no pairs below. With two antidot pins suitably introduced into the film, a single V-AV pair can be stable in the film for $Φ^+ \ge 1.3Φ_0$. At pin separation $\ge 17ξ$, we find the V-AV pair remains pinned after the dipole field is removed, and, so can represent a 1 for a nonvolatile memory.