Ab initio T_c screening for ThCr₂Si₂-type compounds within the BCS theory of superconductivity

ThCr₂Si₂-type (122) compounds have been considered promising candidates for BCS-type superconductors (SCs), but most of their superconductivity have yet to be studied experimentally. Based on their ab initio T_c evaluations, we have performed the high-throughput virtual screening from the Inorganic Crystal Structure Database (ICSD): We first ruled out those which include Cr, Mn, Fe, Co, and Ni atoms, because they might show magnetic ordering that hinders superconductivity.Similarly, the f-electron systems were excluded,because they might show non-BCS-type superconductivity that is beyond the ab initio T_c evaluation. Furthermore, dynamically unstable compounds were removed by performing the ab initio phonon simulations. Thus, 68 compounds remained as candidates for BCS-type SCsand then their T_c values were evaluated by the Allen-Dynes formula. For 30 compounds having experimental T_c values, we investigated the correlation between experimental and theoretical T_c values; they correlate well with each other. Among the remaining 38 compounds, we found SrPb₂Al₂ to have the highest T_c (2.2 K), which is a newly predicted BCS-type SC. We also investigated electronic and phonon band structures as well as the Eliashberg function with mode-resolved electron-phonon coupling constant. Their comparison between SCs and NSCs provides a physical insight into comprehensive understandingof the origin of superconductivity in the 122 compounds, which will be explained in detail in this talk.