First-Principles Design of Halide-Reduced Electrides with Magnetism and Topological Phases

As a novel class of crystals where the excess electrons residing within the cationic framework serve as anions, electrides manifest intriguing magnetic features and topological nature [1], which has aroused great interests among the community of materials science. Here, we propose a design scheme of seeking potential electrides derived from conventional materials. Starting from rare-earth element based halides, we exclude the halogen and perform the global structure optimization, so as to obtain excess electrons confined inside interstitial cavities. Spin polarized interstitial states are realized by chemical substitution with magnetic lanthanides. In addition, band topology is particularly explored for the predicted electrides. In this presentation, we primarily report two families of newly designed electrides, A₂C₂ and A₂Ge (A= Y, Gd, etc.), both of which turn out to be topological nodal line semimetals in the absence of spin-orbit coupling. Our work opens a new avenue to predict electrides, and reveals the close relationship between electrides, magnetism and topological phases.

[1] M. Hirayama, et al. Physical Review X 8.3: 031067 (2018).