Electron-phonon interaction and superconductivity in representative AuCu3-type intermetallic compounds

The AuCu3-type intermetallic compounds are fertile grounds for exploring new superconductors. In order to uncover the generality of the origin of superconductivity and refine an empirical rule to direct finding new superconductors with higher Tc in this kind of compounds, detailed calculations of the electronic structure, phonons and electron-phonon coupling of 8 representative AuCu3-type intermetallic compounds, i.e., ASn3 (A = Ca, La, Y, Na, Li) and YB3 (B = Sn, Pb, Tl, In) categories, were systematically performed from first-principles methods. Among these compounds, the ASn3 (A = Na, Li) were predicted to bear superconductivity with higher Tc. Moreover, we identified different roles of atoms at Au sites and that at Cu sites in determining the physics. The related results indicate that superconductivity mainly originates from the conventional electron-phonon interaction which is mostly dominated by the coupling between electrons from Cu-p states and phonons from low frequency of atoms at Cu sites. More importantly, we empirically found that the electron-phonon coupling is mainly governed by the stiffness of lattice, from which we roughly deduced that the Debye temperature ΘD may be regarded as the tuning factor for finding new superconductors with higher Tc in structures of AuCu3.