Unexpected fourfold symmetry in the resistivity of patterned superconductors

Abstract

We report the magneto-optical observation of a surprising fourfold symmetry of the flux penetration in a superconducting ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ thin-film disk containing a square array of antidots, leading to an angular variation of the critical current by a factor of nearly 2. This behavior is explained using a vortex channeling model. Potential applications in superconducting devices are discussed