New superconducting superhydride LaC2H8 at relatively low stabilization pressure

Motivated by the recent experimental discovery of high-temperature carbonaceous sulfur hydride (C-S-H), we have systematically explored the superconductivity of a carbonaceous lanthanum hydride (C-La-H) ternary compound in the pressure range of 50-250 GPa. Based on first-principles calculations and strong-coupling Migdal-Eliashberg theory, we find that a hitherto unreported LaC2H8 ternary system is dynamically and thermally stable above 70 GPa in a clathrate structure with space group Fm3̄m and exhibits a superconducting critical temperature, Tc, in the range of 69-140 K.