We investigate the current-driven resistive state of two-dimensional Pb–Nb core–shell superconductors within the time-dependent Ginzburg–Landau framework, focusing on how proximity induced inhomogeneity and self field effects govern vortex–antivortex (v-av) dynamics and superconducting fragmentation. The system consists of a type-I Pb core surrounded by a type-II Nb shell coupled through a smooth proximity interface, which produces a spatially nonuniform reduced temperature \(T/T_c(\textbf{r})\) and redistributes both the order parameter and the transport current. By increasing the applied current, we identify a sequence of distinct dynamical regimes. At low currents, dissipation originates from edge-assisted v-av nucleation in the Nb shell, while the Pb core remains a robust superconducting backbone. As the current increases, v-av clusters grow and coalesce inside the Nb layer, progressively suppressing its superconductivity and fragmenting the proximity-coupled network. This process leads to the emergence of isolated Pb superconducting islands that are weakly connected by highly dissipative Nb channels and sustain intermittent phase-slip dynamics. At still higher currents, the Nb shell becomes strongly degraded and transport is governed by edge-driven bursts of v-av activity surrounding the Pb islands, producing a highly nonlinear resistive response. For comparison, we analyze a homogeneous Pb film under the same conditions. Although Pb is a type-I superconductor, the transport self-field induces an intermediate resistive state characterized by a fixed array of superconducting islands embedded in normal regions near the edges. Remarkably, in the high-current limit, the Pb–Nb heterostructure evolves toward a similar island topology, indicating that proximity coupling becomes progressively weaker and self-field effects dominate the spatial organization of superconductivity. Our results establish a mesoscopic framework in which proximity effects, transport self-fields, and vortex dynamics jointly govern dissipative states in hybrid superconducting heterostructures.
