Thermodynamic evidence for a pressure-driven crossover from strong- to weak-coupling superconductivity in Pb
The study used muon-spin rotation measurements to determine the thermodynamic critical field Bc under pressure in Lead (Pb). By comparing the pressure dependence of Bc(0) and Tc, researchers found that their logarithmic derivatives converge at high pressures. This convergence suggests that the coupling strength ratio alpha becomes nearly independent of pressure, providing evidence that compression drives Pb from a strong-coupling superconducting regime toward a weak-coupling limit.