Ductile copper hydride Eliashberg superconductors with Tc in the liquid-nitrogen temperature range and band topology at ambient pressure

Abstract

The engineering demands for superconductors require not only a high transition temperature (T_c) but also eco-friendliness, mechanical workability, and abundance. Currently, superconductors exhibiting both mechanical ductility and T_c above the liquid-nitrogen temperature are still lacking. Considering that copper is one of the most important conductive materials for power transmission, we investigate the synthetic routes, band topology, electron–phonon coupling (EPC) and anharmonic superconductivity of copper hydrides using first-principles calculations. Cubic-Cu₄H₃ remains stable at ambient pressure after kinetic simulations from its experimentally synthesized pressure state. The incorporation of hydrogen impacts the ductility of Cu₄H₃ negligibly compared to copper, while enabling high-T_c superconductivity up to 77 K and non-trivial band topology at ambient pressure. The novel properties arise from the strong EPC, Fermi surface nesting and hydrogen-induced band inversion. This discovery may fill the gap in the lack of ductile superconductors in the liquid-nitrogen temperature range and pave a new way for realizing high-temperature topological superconductivity at atmospheric pressure.