Few‐Hydrogen Metal‐Bonded Perovskite Superconductor MgHCu<sub>3</sub> with a Critical Temperature of 42 K under Atmospheric Pressure
Chong Tian, Yong He, Yaohui Zhu, Juan Du, Shiming Liu, Wenhui Guo, Hongxia Zhong, Jing Lü, Xinqiang Wang, Junjie Shi
Abstract
Abstract Since the prediction of multi‐hydrogen high‐temperature superconductor by Ashcroft in 2004, many possible candidates have been proposed, e.g., LaH 10 showing the highest superconducting transition temperature ( T c ) 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, MgHCu 3 , by combining a novel design idea with first‐principles calculations. Different from multi‐hydrogen hydrides, whose high T c relies on extreme pressure, the metallic bond in few‐hydrogen superconductor MgHCu 3 improves the structural stability and ductility at atmospheric pressure. Here, the small amount of hydrogen is found to be vital for T c . After the incorporation of hydrogen, the electron–phonon coupling constant of MgHCu 3 is increased to 0.83, which is larger than that of the well‐known MgB 2 . Moreover, the anisotropy of MgHCu 3 also plays an important role in enhancing T c . Based on the Migdal‐Eliashberg theory, it predicts that the phonon‐mediated metal‐bonded perovskite MgHCu 3 is a superconductor with T c of 42 K. The first predicted ternary metal‐bonded perovskite, MgHCu 3 , enriches the family of perovskite and will promote further investigation on few‐hydrogen superconductors under atmospheric pressure.