Realization of kagome lattice and superconductivity in topological electrides

Realization of kagome lattice, and hence achieving specific performance, is a challenging issue in condensed matter physics. The corner-sharing triangles of kagome lattice are normally comprised of real atoms occupying certain Wyckoff sites. Here, we propose that the excess electrons in layered electrides ${\mathrm{Mg}}_{3}\mathrm{N}$ and ${\mathrm{Mg}}_{3}\mathrm{O}$ build the two-dimensional kagome lattices. The interstitial electrons further contribute to the nontrivial band topology, i.e., the Dirac points and the Dirac nodal lines in ${\mathrm{Mg}}_{3}\mathrm{N}$ and ${\mathrm{Mg}}_{3}\mathrm{O}$. Further, the in-plane coupling between the electronic orbitals and the atomic vibrational modes dominate the electron-phonon coupling, and yield superconducting critical temperatures approaching 2.0 and 2.2 K for ${\mathrm{Mg}}_{3}\mathrm{N}$ and ${\mathrm{Mg}}_{3}\mathrm{O}$, respectively. This work proposes a feasible scheme to construct kagome lattices by interstitial quasiatoms and provides a promising platform to explore the superconductivity and nontrivial band topology in kagome electrides.