The recent discovery of high-pressure hydrides has revealed superconducting critical temperatures ($T_{\mathrm{c}}$) surpassing 200 K above 150 GPa, advancing the pursuit of room-temperature superconductivity. Although ongoing research aims to elevate the $T_{\mathrm{c}}$ in these systems further, addressing the challenges associated with their high-pressure synthesis remains an essential task. Inspired by the recent prediction of high-temperature superconductivity in $\mathrm{La}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$, we explore its isostructural counterparts $\mathrm{Ce}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$ and $\mathrm{Th}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$ using ab initio methods. Our calculations reveal that chemical substitution of La with Ce or Th substantially lowers the stabilization pressure. Specifically, the Ce and Th variants are found to be thermodynamically stable above 185 and 200 GPa, respectively, compared to 242 GPa for $\mathrm{La}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$. Harmonic calculations yield $T_{\mathrm{c}}$ values of 204 K at 200 GPa for $\mathrm{Ce}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$ and 230 K at 210 GPa for $\mathrm{Th}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$. Notably, when anharmonic effects are included for $\mathrm{Ce}{\mathrm{Sc}}_2{\mathrm{H}}_{24}$, it reduces its dynamic stability pressure to 100 GPa while retaining a high $T_{\mathrm{c}}$ of 216 K. The crucial synergy between chemical precompression mediated by delocalized $f$ electrons, which substantially reduces the stabilization pressure, and the inclusion of anharmonic quantum nuclear effects, which provides a more precise physical description leading to a further dramatic reduction of the dynamic stability pressure, is essential for accurately predicting the high-$T_{\mathrm{c}}$ superconductivity in these hydrides at experimentally relevant pressures. Our results establish a foundation for targeted exploration of high-$T_{\mathrm{c}}$ superconductors under milder experimental conditions.

Close

PrevNext

View figure in article

• Superconductivity
• Superconductors
• Clathrates
• High-temperature superconductors
• BCS theory
• Density functional theory