Two-dimensional non–van der Waals niobium nitride nanosheets with high-temperature two-gap superconductivity

Abstract

The exploration of the superconductivity in two-dimensional materials has garnered significant attention due to their promising low-power applications and fundamental scientific interest. Here, we report some stable non–van der Waals NbxNx+1 (x=1–4) monolayers derived from the NbN bulk exfoliated along the [001] direction, as identified through first-principles calculations. Among these monolayers, Nb2N3, which crystallizes in the P6¯m2 symmetry, stands out with an exceptional superconducting transition temperature of 77.8 K, setting a new high-Tc benchmark for two-dimensional transition-metal nitrides and binary compounds. Our detailed analysis reveals that the strong superconductivity in Nb2N3 is driven by phonon modes dominated by N vibrations, with significant electron-phonon coupling contributions from N-p and Nb-d electronic states. Using the anisotropic Migdal-Eliashberg framework, we further determine the two-gap nature of the superconductivity in the Nb2N3 monolayer, characterized by pronounced electron-phonon coupling and anisotropic energy gaps. These results advance our understanding of superconductivity in two-dimensional transition-metal nitride and highlight their potential for nanoscale superconducting applications.

Source-reported materials — not catalogue approval

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