Ambient-pressure high-temperature superconductivity exceeding 100 K in three-dimensional carbon structures

In order to explore the high-temperature superconductivity of novel carbon structures at ambient pressure, we have investigated the crystal structures, electronic states, dynamics, and electron-phonon interactions of carbonhydrogen (carbon-rich) system by means of structural search predictions as well as first-principles calculations. A novel three-dimensional carbon structure intercalated by hydrogen atoms, P63/mcm HC6, is obtained. The results show that P63/mcm HC6 is thermodynamically and dynamically stable at ambient pressure. This is a carbonbased structure, and its stability mainly comes from the strong covalent hybridization between carbon and carbon. The role of hydrogen is mainly to introduce hybrid energy bands in the band gap to promote metallization, and the electron-phonon coupling is mainly contributed by carbon. The superconducting transition temperature of P63/mcm HC6 reaches 107 K at ambient pressure. Comparing carbon and carbonlike structured superconductors, we point out that three-dimensional carbon or carbonlike structures are an interesting direction for exploring ambient-pressure high-temperature superconductivity.