Second generation of vortex-antivortex states in mesoscopie superconductors: Stabilization by artificial pinning

摘要

Antagonistic symmetries of superconducting polygons and their induced niultivorle.x states in a homogeneous magnetic field may lead to the appearance of antivorlices in the vicinity of the superconductingormal-state boundary (where mesoscopie confinement is particularly strong). Resulting vortex-antivortex (V-Av) molecules match the sample symmetry but are extremely sensitive to defects and fluctuations and remain undetected experimentally. Here we show that V-Av states can reappear deep in the superconducting state due to an array of perforations in a polygonal setting, surrounding a central hole. Such states are no longer caused by the symmetry of the sample but rather by pinning itself, which prevents the vortex-antivortex annihilation. As a result, even micron size, clearly spaced V-Av molecules can be stabilized in large mesoscopie samples.