Electron-phonon interaction and superconductivity in the silicon-boron-carbon monolayers with high stability.

Recently, considerable attention has been given to the exploration of superconductivity in low-dimensional materials. By employing unbiased structure search and first-principles calculations, we systematically investigate the structural and electronic properties of the predicted two-dimensional (2D) compounds SiBC4, SiBC6, and SiB4C in the monolayer limit. These structures demonstrate high thermal stability at 1,500 K and meet the criteria for mechanical and dynamic stability. Most importantly, they are identified as intrinsic superconductors with superconducting transition temperatures (T c ) of 17.59, 12.18, and 10.91 K, respectively. The van Hove singularity caused by the high density of states near the Fermi surface plays a crucial role in the emergence of superconductivity. Furthermore, by applying compressive/tensile strains on SiBC4, it is observed that the tensile strain dramatically softens the phonon branch, as well as increases the electron-phonon coupling (EPC) and T c . Our findings not only contribute to the development of novel 2D superconducting materials but also present an excellent platform to investigate the role of van Hove singularity in emergent superconductivity.