Superconductivity in CeBeH$_{8}$ and CeBH$_{8}$ at moderate pressures

TL;DR

This study predicts high-temperature superconductivity in CeBeH$_{8}$ and CeBH$_{8}$ under moderate to high pressures, identifying stable phases and their transition temperatures through high-pressure structural analysis.

Contribution

The paper reports the discovery of new superconducting phases in CeBeH$_{8}$ and CeBH$_{8}$ with specific transition temperatures and stable pressure ranges, expanding the family of ternary hydrides.

Findings

CeBeH$_{8}$ has a $T_c$ of 56 K at 10 GPa.

CeBH$_{8}$ exhibits a maximum $T_c$ of 118 K at 150 GPa.

Multiple stable phases of CeBH$_{8}$ are identified with high $T_c$ at high pressures.

Abstract

High-pressure structural searches of superhydrides CeBeH$_8$ and CeBH$_8$ were performed under ambient pressure up to 300 GPa. We identify $Fm\overline{3}m$-CeBeH$_8$ with a superconducting transition temperature $T_{c}$ of 56 K at 10 GPa. Two more phases with spacegroup $R\overline{3}m$ and $C2/m$, were investigated within the increasing pressures. CeBH$_8$ shows a similar phase transition process as CeBeH$_8$ but with higher transition pressures and higher $T_c$. $Fm\overline{3}m$-CeBH$_8$ is predicted to be superconducting above 120 GPa with a maximum $T_{c}$ of 118 K at 150 GPa. $R\overline{3}m$-CeBH$_8$ and $C2/m$-CeBH$_8$ are dynamically stable above 120 GPa and 100 GPa, respectively. The maximum $T_{c}$ is 123 K at 195 GPa for $R\overline{3}m$-CeBH$_8$, and 115 K at 350 GPa for $C2/m$-CeBH$_8$. Our work enriches the family of ternary hydrides and may provide a useful guideline for further search for superconducting hydrides at low and moderate pressures.