Emergence of superconductivity in Dirac nodal-line Cu2Si monolayer: Ab initio calculations
Following the prediction given by the first-principles simulations [J. Am. Chem. Soc. 137, 2757 (2015)], the Dirac nodal-line Cu2Si monolayer has been successfully synthesized on the Cu(111) surface [Nat. Commun. 8, 1007 (2017)] or on the Si(111) substrate [Phys. Rev. Mater. 3, 044004 (2019)]. However, its superconducting properties have never been reported in experiment and theory. Here, through first-principles calculations, we study its electron, phonon properties and electron-phonon coupling to investigate the possibility of superconductivity for metallic Cu2Si monolayer. Results show that it is an intrinsic BCS-type superconductor, with estimated superconducting temperature Tc being ∼4.1 K. We further find that the Fermi surface nesting is partially responsible for its superconducting character. Carrier doping as well as biaxial strains will suppress the Tc. Our results help to explain the challenges to experimentally probe superconductivity in substrate-supported Cu2Si monolayer but do provide clues for further experiments.