Few‐Hydrogen Metal‐Bonded Perovskite Superconductor MgHCu3 with a Critical Temperature of 42 K under Atmospheric Pressure

Abstract

AbstractSince the prediction of multi‐hydrogen high‐temperature superconductor by Ashcroft in 2004, many possible candidates have been proposed, e.g., LaH10 showing the highest superconducting transition temperature (Tc) around 250–260 K at 170‐200 GPa hitherto. However, this pressure is too large to be taken into practical use. To address this challenge, it proposes a few‐hydrogen metal‐bonded perovskite superconductor, MgHCu3, by combining a novel design idea with first‐principles calculations. Different from multi‐hydrogen hydrides, whose high Tc relies on extreme pressure, the metallic bond in few‐hydrogen superconductor MgHCu3 improves the structural stability and ductility at atmospheric pressure. Here, the small amount of hydrogen is found to be vital for Tc. After the incorporation of hydrogen, the electron–phonon coupling constant of MgHCu3 is increased to 0.83, which is larger than that of the well‐known MgB2. Moreover, the anisotropy of MgHCu3 also plays an important role in enhancing Tc. Based on the Migdal‐Eliashberg theory, it predicts that the phonon‐mediated metal‐bonded perovskite MgHCu3 is a superconductor with Tc of 42 K. The first predicted ternary metal‐bonded perovskite, MgHCu3, enriches the family of perovskite and will promote further investigation on few‐hydrogen superconductors under atmospheric pressure.