Prediction of 1:1 kagome metals with superconductivity and band topology

Abstract

Kagome superconductors featuring topologically nontrivial band structures have attracted extensive research interest. FeSn and CoSn is a new kind of kagome material with intrinsic magnetism, which suppresses the emergence of superconductivity. Here, we theoretically predict a new kind of 1:1 kagome MSn (M=transition metal), which exhibit intrinsic superconductivity and nontrivial band topology by first-principles calculations. Among twenty-seven candidates, MSn (M= Mo, Hf, Nb, Ta, W, Ti) are theoretically identified as both dynamically and thermodynamical stable. And, five non-magnetic MSn (M= Mo, Hf, Nb, Ta, W) exhibit phonon-mediated superconductivity. Especially, the d orbitals bands display Dirac points and van Hove singularities near the Fermi level, which contribute to the emergence of topology and the electron-phonon coupling (EPC). More interestingly, MoSn, HfSn and NbSn show nontrivial topological band structure at the Fermi level. Thus, the predicted MSn establish a platform integrating superconductivity and topological order.