Prediction of superconductivity in Haeckelite compounds using first-principles calculations

Research into the superconducting characteristics of materials has intrigued scientists for an extended period. This study examines the superconductivity of 3D metallic Haeckelite compounds (XY), characterized by square-octagonal structures and $P{4}_2/mnm$ symmetry group. Utilizing first-principles calculations, we have performed a thorough examination of the dynamic stability, electronic structures, and electron-phonon coupling (EPC) in Haeckelite structures containing elements $X=B,\text{Be},\text{Ni},\text{Pd},\text{Pt},\text{Cu}$ and $Y=C,O,\text{Se},S,\text{Si},\text{Te}$ . Our analysis indicates that 14 compounds demonstrate both mechanical and dynamic stability with superconducting transition temperatures ( $T_c$ ) ranging from $\sim 0.1K$ to $15.7K$ . Among these, BeC and BC exhibit the highest $T_c$ of $11.3K$ and $15.7K$ , respectively, with corresponding superconducting gaps of $1.8\text{meV}$ and $2.4\text{meV}$ . This study clarifies the relationships between electronic structures, phonon characteristics, and superconductivity in Haeckelite compounds through the application of Eliashberg equations.