Topological and nodal superconductor kagome magnesium triboride

Abstract

Recently the kagome compounds have inspired enormous interest and made some great progress such as in the field of superconductivity and topology. Here we predict a different kagome magnesium triboride $(\mathrm{Mg}{\mathrm{B}}_{3})$ superconductor with a calculated ${T}_{c}\ensuremath{\sim}12.2\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ and ${T}_{c}\ensuremath{\sim}15.4$ K by external stress, the potentially highest among the reported diverse kagome-type superconductors. We reveal its various exotic physical properties including the van Hove singularity, flat-band, multiple Dirac points, and nontrivial topology. The system can be described by a two-band model with highly anisotropic superconducting gaps on Fermi surfaces. Its topological and nodal superconducting nature is unveiled by a recently developed symmetry indicators method. Our results suggest that $\mathrm{Mg}{\mathrm{B}}_{3}$ can be a new platform to study exotic physics in the kagome structure, and pave a way to seek for more superconductors and topological materials with $X{Y}_{3}\text{\ensuremath{-}}\mathrm{type}$ kagome lattice.