A first-principles prediction of two-dimensional superconductivity in pristine B2C single layers

Abstract

Based on first-principles lattice dynamics and electron–phonon coupling calculations, B₂C sheets are predicted to be a two-dimensional (2D) phonon-mediated superconductors with a relatively high transition temperature (T_c). The electron–phonon coupling parameter was calculated to be 0.92 and it is mainly contributed by low frequency out-of-plane phonon modes and electronic states with a π character. When the Coulomb pseudopotential, μ*, is set to 0.10, the estimated temperature, T_c, is 19.2 K. To the best of our knowledge, B₂C is the first pristine 2D superconductor with a T_c higher than the boiling point of liquid helium.