Mg7LiH Crystal Structure

Ambient-pressure high-temperature superconductivity in low-hydrogen compounds paves the way for superconducting devices operating without extreme conditions. This study introduces a light-element doping strategy, successfully designing the low-hydrogen, metal-bonded layered superconductor Mg$_7$LiH. This material demonstrates superconductivity with a superconducting transition temperature ($T_c$) of 59 K and a $H_c$ of 8864 Oe under ambient pressure while maintaining excellent ductility. Hydrogen atoms dominate the electron-phonon coupling (EPC) mechanism governing $T_c$. Compared with (Mg$_4)_2$H, Mg$_7$LiH exhibits superior superconductivity, which arise from Li-induced charge transfer, elevated electronic density of states (DOS) at the Fermi level, and improved Fermi surface nesting. This work not only validates light-element doping as an effective approach to tune superconducting properties in low-hydrogen hydrides but also provides theoretical guidance for experimentally synthesizing high-performance superconductors at ambient pressure.