Strong Electron–Phonon Coupling in 3D WN and Coexistence of Intrinsic Superconductivity and Topological Nodal Line in Its 2D Limit

Abstract

The electron–phonon coupling (EPC) and superconductivity in three‐component‐fermion materials WN, WC, and TaN are systematically investigated using first‐principles calculations. The EPC strength in pristine or pressurized WC and TaN are found to be negligibly weak (<0.2), but can be enhanced significantly by electron doping, and the predicted transition temperatures (Tc) reach the values observed in experiments (≈4 K), demonstrating the vital role of charge doping in the formation of superconductivity. Surprisingly, pristine WN has strong EPC due to a synergistic effect of strong Fermi nesting and large deformation potential and behaves as a good superconductor with Tc of 31 K. Going down from 3D to 2D, WN thin film (i.e., monolayer W3N4) is also predicted to be an intrinsic superconductor with Tc of 11 K. Most importantly, monolayer W3N4 hosts nodal lines that are robust against spin–orbit coupling (SOC), close to the Fermi level and apart from other trivial bands, which are scarce in real materials. The coexistence of high‐transition‐temperature superconductivity and topological states in 3D and 2D WN render them promising platforms for realizing topological superconductivity.