Calculation of the electron-phonon interaction strength ${\lambda }_{\mathrm{ep}}$ using the conventional theory for metals, which should be applicable in the normal regime, leads to the very small value of 0.035 for the heavy-fermion superconductor U${\mathrm{Be}}_{13}$. It is argued that the interactions responsible for the large observed mass enhancement in the heavy-fermion regime will tend to further decrease ${\lambda }_{\mathrm{ep}}$, strengthening the conventional wisdom that either unconventional electron-phonon coupling or electronic interactions are responsible for pairing.

• Received 14 July 1986

DOI:https://doi.org/10.1103/PhysRevB.34.6546