Flexible Amorphous Superconducting Materials and Quantum Devices with Unexpected Tunability

In superconductivity, electrons exhibit unique macroscopic collective quantum behavior that is the key for many modern quantum technologies. This electron behavior stems vastly from coupling to a correlated motion of atoms in the material, as well as from synchronized directional movement that screens external magnetic fields perfectly. Hence, the inter-atomic distance and material geometry are expected to affect fundamental superconductive characteristics. These parameters are tunable with strain, but strain application is hindered by the rigidity of superconductors, which in turn increases at device-relevant temperatures. Here, we present flexible, foldable and transferable superconducting materials, and functional quantum nanostructures by depositing superconductive amorphous-alloy films on a flexible adhesive tape. Specifically, flexible superconducting films, nanowires and quantum interference devices (SQUIDs) were fabricated and characterized under variable magnetic-field, current, temperature and flexure conditions. The SQUID interference periodicity, which represents a single flux quantum, exhibits unexpected tunability with folding curvature. This tunability raises a need for a relook at the fundamentals of superconductivity, mainly with respect to effects of geometry, magnetic-field inhomogeneity and strain. Our work paves the way for novel magnetic devices and quantum-technology platforms with local tunability.