Soft vortex matter in a type-I/type-II superconducting bilayer

Abstract

Magnetic flux patterns are known to strongly differ in the intermediate state of type-I and type-II superconductors. Using a type-I/type-II bilayer we demonstrate hybridization of these flux phases into a plethora of unique new ones. Owing to a complicated multi-body interaction between individual fluxoids, many different intriguing patterns are possible under applied magnetic field, such as few-vortex clusters, vortex chains, mazes or labyrinthal structures resembling the phenomena readily encountered in soft matter physics. However, in our system the patterns are tunable by sample parameters, magnetic field, current and temperature, which reveals transitions from short-range clustering to long-range ordered phases such as parallel chains, gels, glasses and crystalline vortex lattices, or phases where lamellar type-I flux domains in one layer serve as a bedding potential for type-II vortices in the other - configurations clearly beyond the soft-matter analogy.