Route to a Superconducting Phase above Room Temperature in Electron-Doped Hydride Compounds under High Pressure

TLDR

Record‑temperature superconductivity (~250 K) in LaH₁₀ marks progress toward room‑temperature superconductors, and the ternary Li₂MgH₁₆ mimics an electron‑doped MgH₁₆ whose parent hydride contains H₂ molecules and is a poor superconductor. The study aims to identify the Li₂MgH₁₆ clathrate as a candidate for room‑temperature or higher‑temperature superconductivity, predicting a Tc of ~473 K at 250 GPa. Adding electrons breaks H₂ molecules, raising atomic hydrogen content and stabilizing the clathrate structure needed for high‑Tc superconductivity. Our results show that electron donation through metal doping tunes superconductivity in hydrogen‑rich hydrides and could guide the discovery of high‑Tc superconductors in other ternary or quaternary hydrides.

Abstract

The recent theory-orientated discovery of record high-temperature superconductivity (T_{c}∼250 K) in sodalitelike clathrate LaH_{10} is an important advance toward room-temperature superconductors. Here, we identify an alternative clathrate structure in ternary Li_{2}MgH_{16} with a remarkably high estimated T_{c} of ∼473 K at 250 GPa, which may allow us to obtain room-temperature or even higher-temperature superconductivity. The ternary compound mimics a Li- or electron-doped binary hydride of MgH_{16}. The parent hydride contains H_{2} molecules and is not a good superconductor. The extra electrons introduced break up the H_{2} molecules, increasing the amount of atomic hydrogen compared with the parent hydride, which is necessary for stabilizing the clathrate structure or other high-T_{c} structures. Our results provide a viable strategy for tuning the superconductivity of hydrogen-rich hydrides by donating electrons to hydrides via metal doping. Our approach may pave the way for finding high-T_{c} superconductors in a variety of ternary or quaternary hydrides.