Prediction of ambient pressure superconductivity in cubic ternary hydrides with MH$_6$ octahedra

Exploring high-temperature superconducting (high-$T_c$) material at ambient pressure holds immense significance for physics, chemistry, and materials science. In this study, we perform a high-throughput screening of strong electron-phonon interactions in X$_2$MH$_6$ compounds (X = Li, Na, Mg, Al, K, Ca, Ga, Rb, Sr, and In; M are $3d$, $4d$, and $5d$ transition metals). These compounds have a cubic structure featuring an MH$_6$ octahedron motif. Our screening calculations suggest that 26 compounds exhibit dynamic stability and strong electron-phonon coupling. Among these 26 compounds, Mg$_2$RhH$_6$, Mg$_2$IrH$_6$, Al$_2$MnH$_6$, and Li$_2$CuH$_6$ show promising energetic stability and $T_c$ of more than 50 K at ambient pressure. This study underscores promising high-$T_c$ compounds at ambient pressure with distinctive MH$_6$ motifs.