Theoretical Insights into High-T_c Superconductivity of Structurally Ordered YThH₁₈: A First-Principles Study

There has been a marked increase in interest in high-temperature superconductors over the past few years, sparked by their potential to revolutionize multiple fields, including energy generation and transportation. A particularly promising avenue of exploration has emerged in the form of ternary superhydrides, compounds composed of hydrogen along with two other rare-earth elements. Our investigation focuses on the search for Y-Th-H ternary compounds; employing an evolutionary search methodology complemented by electron-phonon calculations reveals a stable superhydride, P6̅m2-YThH₁₈, capable of exhibiting a critical temperature (T_c) as high as 222 K at 200 GPa along a few low-T_c novel hydrides. Our analysis explores the possibility of alloyed structure formation from the disordered condition of Th-doped YH₉ and establishes that the P6̅m2-YThH₁₈ is indeed a structurally ordered structure. This opens up an exciting avenue for research on multinary superhydrides, which could facilitate experimental synthesis and provides potential implications for high-temperature superconductivity research.