Role of electronic correlations in high-pressure rare-earth superhydrides

Determine the role of electronic correlations, induced by the f-electrons of rare-earth elements, in high-pressure rare-earth superhydrides in order to understand their physical properties and superconductivity mechanisms.

Background

Rare-earth superhydrides have emerged as promising high-temperature superconductors under extreme pressures, but their 4f-electron states are localized and strongly correlated, challenging standard density functional theory descriptions. This raises fundamental questions about how many-body electronic correlations influence their electronic structure, phonons, and electron-phonon coupling.

The paper focuses on CeH9 as a representative system and uses a combined DFT+DMFT and Migdal-Eliashberg approach to quantify correlation effects on electrons and phonons, aiming to reconcile theoretical predictions with experimental critical temperatures. Despite progress for CeH9, the general question remains relevant across rare-earth superhydrides.