Superconductivity in Ca3H2 electride at moderate pressure

The discovery of superconductivity electrides in hydrides has fueled enthusiasm due to their inherent physical characteristics generated from localized anionic electrons. In this work, using density functional theory (DFT), we discover a remarkable hydrogen-based electride superconductor Ca3H2 with the P63/mmc symmetry. The thermal stability and lattice dynamical stability of this novel electride have been confirmed by ab initio molecular dynamics simulations and phonon calculations. Interestingly, the superconducting critical temperature T-c of Ca3H2 increases with pressure and exhibits the highest T-c value of 8.4 K under 19.5 GPa, which shows distinguished superconductivity at a moderate pressure range compared with other electrides. Moreover, the mainly physical origin of the rise of T-c has been revealed, in which the electron occupancy of Ca-d orbitals increases their coupling with low-frequency phonons dominated by out-of-plane vibration with the increase of pressure. This work will enrich the realization of hydrogen-based electrides and shed light on the discovery of superconducting electrides at moderate pressures.

Automated summary

In this study, a new hydrogen-based electride superconductor Ca3H2 with distinct superconductivity at moderate pressures is discovered using density functional theory. The increase in superconducting critical temperature Tc of Ca3H2 with pressure is found, and the physical origin of this increase is revealed.