Finite-Frequency Electrodynamics of Gate-Tuned Superconductivity in Monolayer WTe₂

Monolayer WTe₂ offers a gate-tunable platform for exploring a clean, two-dimensional superconductor–insulator transition embedded within a topological band structure: superconductivity emerges from a quantum spin Hall insulator as carrier density is tuned electrostatically. We present a new method to probe the RF–microwave electrodynamics of van der Waals superconductors. These measurements directly access superfluid stiffness and fluctuation dynamics by disentangling inductive response from dissipation—quantities that conventional DC transport obscures once resistance vanishes. Applied to WTe₂, our approach reveals the evolution of complex conductivity across temperature and carrier density, alongside DC transport, uncovering spectral-weight redistribution and extracting finite-frequency phase stiffness and vortex dynamics consistent with the two-dimensional limit.