Superconductivity in ${\mathrm{Ba}}_{1\mathrm{-}\mathit{x}}$${\mathrm{K}}_{\mathit{x}}$${\mathrm{BiO}}_3$ is studied within the framework of Eliashberg theory using a model of the electron-phonon interaction, ${\mathrm{\alpha }}^2$F(ω). The model is based upon molecular-dynamics calculations of the phonon density of states, which are in good agreement with inelastic-neutron-scattering experiments. The function α(ω) is constructed using information from electron-tunneling experiments. Our model is constructed with the premise that the electron-phonon coupling constant λ≊1 and that strong electron-phonon coupling exists for high-energy (30–60 meV) phonon modes. Superconducting properties of the material at zero and finite temperatures are calculated and compared with experiments.

• Received 12 November 1991

DOI:https://doi.org/10.1103/PhysRevB.45.5535