Anisotropic superconductivity in the two-dimensional metal-organic kagome framework Cu₃(CO)₆

Motivated by the theoretical prediction of superconductivity in the Cu₃(CS)₆ monolayer and the successful experimental realization of its analogous oxygen counterpart Cu₃(CO)₆ monolayer [X. Zhang et al., Nano Lett. 17, 6166 (2017); R. Zhang et al., Angew. Chem. 132, 2691 (2020); N. Shaiek et al., Adv. Mater. Interfaces 9, 2201099 (2022)], we present a comprehensive theoretical investigation of phonons and the electron-phonon coupling mechanism in the Cu₃(CO)₆ monolayer. Our first-principles calculations reveal that this well-defined two-dimensional metal-organic framework (2D-MOF) is a superconductor with a critical temperature of 16.5 K. This robust superconductivity is driven by a strong electron-phonon coupling (λ = 0.72), predominantly contributed by the strong interaction between low-energy phonons (dominated by Cu and O atoms) and electronic states (formed by Cu d_xy,x2_−y2 and O s + p_x,y orbitals) near the Fermi level. Furthermore, we find that Cu₃(CO)₆ monolayer exhibits a Bardeen-Cooper-Schrieffer superconducting state characterized by a single anisotropic gap. Our findings in 2D-MOFs highlight the great potential for exploring superconductivity in this promising class of materials.