Superconductivity in atom-intercalated quaternary hydrides under ambient pressure

Abstract: Hydrogen-rich materials are the most promising candidates for high-temperature conventional superconductors under ambient pressure. Multinary hydrides have abundant structural configurations and are more promising to find high-temperature superconductors at ambient pressure, but searching for multinary materials in complex phase space is a great challenge. In this work, we used our developed AI search engine (InvDesFlow) to perform extensive investigations regarding ambient stable superconducting hydrides. Several quaternary hydrides with high superconducting temperature~($T_c$) are predicted. In particular, the superconducting $T_c$ of K$_2$GaCuH$_6$ and K$_2$LiCuH$_6$ are calculated to be 68~K and 53~K under ambient pressure, respectively, which shows a significant enhancement in comparison with that of K$_2$CuH$_6$~($T_c$ $\sim$ 16~K). We also find that intercalating atoms could cause phonon softening and induce more phonon modes with strong electron-phonon coupling. Hence, we propose that intercalating atoms is a feasible approach in searching for superconducting quaternary hydrides.