Enhanced superconductivity by strain and carrier-doping in borophene: A first principles prediction

We predict by first principles calculations that the recently prepared borophene is a pristine two-dimensional (2D) monolayer superconductor, in which the superconductivity can be significantly enhanced by strain and charge carrier doping. The intrinsic metallic ground state with high density of states at Fermi energy and strong Fermi surface nesting lead to sizeable electron-phonon coupling, making the freestanding borophene superconduct with $T_c$ close to 19.0 K. The tensile strain can increase $T_c$ to 27.4 K, while the hole doping can notably increase $T_c$ to 34.8 K. The results indicate that the borophene grown on substrates with large lattice parameters or under photoexcitation can show enhanced superconductivity with $T_c$ far more above liquid hydrogen temperature of 20.3 K, which will largely broaden the applications of such novel material.