Flexible Amorphous Superconducting Materials and Quantum Devices with Unexpected Tunability

In superconductors, electrons exhibit a unique macroscopic quantum behavior, which is the key for many modern quantum technologies. Superconductivity stems from coupling between electrons and synchronized atom motion in the material. 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 developed flexible, foldable and transferable superconducting materials and functional quantum nanostructures. These materials were obtained by depositing superconductive amorphous-alloy films on a flexible adhesive tape. Specifically, we fabricated flexible superconducting films, nanowires and quantum interference devices (SQUIDs) and characterized them under variable magnetic-field, current, temperature and flexure conditions. The SQUID interference periodicity, which represents a single flux quantum, exhibits unprecedented and 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 supplies a novel platform for quantum and magnetic devices with local tunability. 2