Superconductivity in the Ce–B–H system at high pressure

Abstract

Ternary hydrides are considered as promising materials for high temperature (T_c) superconductors under high pressure due to the expansion of the configuration space compared to binary hydrides. Here, by using a swarm intelligence structure search method combined with density functional theory, we investigate the crystal structures, the electronic properties and the superconductivity of Ce–B–H systems at 100 GPa and 200 GPa. We identified six thermodynamically stable Ce–B–H compounds, namely CeBH, CeBH₆, CeBH₇, Ce₂BH₁₄, Ce₂BH₁₆ and CeB₂H₃. All of them exhibit a metallic nature. Among these, CeBH₆, Ce₂BH₁₄, and Ce₂BH₁₆ are predicted to be superconducting, and Ce₂BH₁₄ exhibits the maximum T_c of 64 K at 100 GPa. The analysis reveals that the coupling between the f electrons from metal Ce and phonons derived from B and H at mid-frequencies plays a key role in the superconductivity. Our results could be used to guide future experimental synthesis of new ternary hydrides with the aid of high pressure.