Tuning the Electron-Phonon and Superconducting Coupling in InPb Bimetallic Alloys.

Electron-phonon coupling is a fundamental inelastic interaction in solid-state physics and superconductors. Here we probe electron-phonon and superconducting coupling strength by tuning the indium composition in In qPb1- q superconducting bimetallic alloys. A crossover from weak to strong coupling strength was observed through the analysis of crystal structure and superconducting phase diagrams. The hole-doped Pb solid solution showed suppressed TC and subverted coupling strength due to decreased density of state N(0) and hardened phonons, while the electron-doped In solid solution revealed enhanced TC and stronger coupling strength because of increased N(0) and softened phonons. Our results are in agreement with the Ginzburg-Landau theory calculations regarding the dirty limits and are well described by the Allen and Dynes formula within the framework of the McMillan formalism.