Coexisting Type-I nodal Loop, Hybrid nodal loop and nodal surface in electride Li5Sn

Abstract

Topological electride as a quantum material, which possess unique electronic properties of both electrides and topological materials, have garnered widespread attention, showcasing vast potential application in electronic device and beyond. However, the number of electride materials exhibiting multiple topological phases remains limited. In this work, based on first-principles calculations and symmetry analysis, we present Li₅Sn as a electride, characterized by various topological nodal loops and nodal surfaces. The Li₅Sn contains interstitial electrons confined in zero-dimensional lattice cavities. The bands predominantly contributed by these interstitial electrons give rise to multiple topological phases, including Type-I and Hybrid nodal loops in the k_z = 0 plane, and nodal surfaces in the k_z = π/c plane. Symmetry analysis reveals that these nodal loops are protected by two independent mechanisms: the coexistence of spatial inversion (P) and time-reversal (T) symmetries, and mirror (M_z) symmetry. The resulting drumhead surface states are clearly observable. In summary, our research offers a platform for exploring the novel properties of topological electrides.