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 novel stable non-van der Waals NbxNx+1 (x = 1-4) monolayers derived from the NbN bulk exfoliated along the (001) plane, as identified through first-principles calculations. Among these monolayers, Nb2N3, which crystallizes in the P6m2 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 2D transition metal nitride and highlight their potential for nanoscale superconducting applications.
@article{arxiv.2504.20868,
title = {Two-dimensional non-van der Waals niobium nitride nanosheets with high-temperature two-gap superconductivity},
author = {Si-Yi Xiong and Peng Jiang and Yiming Wang and Yan-Ling Li},
journal= {arXiv preprint arXiv:2504.20868},
year = {2025}
}