Prediction of a Two-Gap High-T Superconducting Covalent Organic Framework

Metallization of covalent bonds can bring about superconductivity in covalent materials. Mostly, it is achieved either by introducing dopants into the semiconducting parent compounds or by shifting the Fermi level by external gating. Intrinsic superconductivity in pure covalent materials is rare. In this work, we predict the intrinsic superconductivity in a previously proposed two-dimensional covalent organic framework (COF). The metallization of covalent bonds is achieved by making the lone pairs of nitrogen atoms partially participate in bonding. More interestingly, our calculations of electron-phonon couplings and anisotropic Migdal-Eliashberg theory indicate that it is a two-gap superconductor with a transition temperature (T) of ∼85 K. Our work not only proposes a new superconducting COF but also provides a guideline to search for metallic COFs and conventional high-T superconductors with metallic covalent bonds.