Strain-induced multigap superconductivity in electrene Mo2N: a first principles study

Abstract

Superconductivity in low dimensional materials and 2D electrides are topics of great interest with possible applications in next generation electronic devices. Using density functional theory (DFT) associated with Migdal-Eliashberg approach and maximally localized Wannier functions this study shows how biaxial strain affects superconductivity in a monolayer of Mo₂N. Results indicate that 2D Mo₂N presents strong electron–phonon coupling with large anisotropy in the superconducting energy gap. It is also proposed that, at low temperatures, a single layer of Mo₂N becomes an electride with localized electron gas pockets on the surface, resembling anions adsorbed on an atomic sheet. Calculations point to T_c = 24.7 K, a record high transition temperature for this class of material at ambient pressure. Furthermore, it is shown that when biaxial strain is applied to a superconducting Mo₂N monolayer, a new superconductivity gap starts at 2% strain and is enhanced by continuum strain, opening additional coupling channels.