Resistive states due to the interplay of flux flow and vortex dynamics in artificially defected granular superconductors within the Ginzburg–Landau theory

In type-II superconductors, transport currents interact with vortices via the Lorentz force (FL), which induces vortex motion when it exceeds the pinning force (FP) that anchors them. This motion results in the onset of energy dissipation. In this work, we investigate vortex dynamics in a long superconducting tape composed of tailored grains connected by weak links-regions with reduced critical temperature-and incorporating various intra-grain defect configurations. By numerically solving the generalized time-dependent Ginzburg-Landau equations, we analyze the systems' response to varying magnetic fields and increasing transport currents. Our simulations reveal that, although intra-grain defects are not efficient at pinning vortices, they guide vortex trajectories and delay their motion, thereby influencing the onset of the resistive state. At lower fields, the defects enable the coalescence of intra-grain vortices with inter-grain vortices, promoting negative differential resistance. A Fraunhofer-like pattern in the critical current was observed at low fields, resembling the Josephson-junction behavior of the weak links. These findings may provide valuable design insights for the development of granular superconductors in applications such as sensors and emerging quantum technologies.