Abstract
Recent discoveries of topological phases realized in electronic states in solids have revealed an important role of topology, which ubiquitously appears in various materials in nature. Many well-known materials have turned out to be topological materials, and this new viewpoint of topology has opened a new horizon in material science. In this paper we find that electrides are suitable for achieving various topological phases, including topological insulating and topological semimetal phases. In the electrides, in which electrons serve as anions, the bands occupied by the anionic electrons lie near the Fermi level, because the anionic electrons are weakly bound by the lattice. This property of the electrides is favorable for achieving band inversions needed for topological phases, and thus the electrides are prone to topological phases. From such a point of view, we find many topological electrides, Y$_2$C (nodal-line semimetal (NLS)), Sc$_2$C (insulator with $\pi$ Zak phase), Sr$_2$Bi (NLS), HfBr (quantum spin Hall system), and LaBr (quantum anomalous Hall insulator), by using ab initio calculation. The close relationship between the electrides and the topological materials is useful in material science in both fields.
Highlights
In recent years, a number of topological materials, such as topological insulators [1,2,3] and topological semimetals [4,5], have been found by various theoretical and experimental approaches
We show that some electride materials such as Y2C and Sc2C are topological materials, and some topological materials such as Sr2Bi, HfBr, and LaBr are electrides
We show that electrides are favorable for achieving band inversion
Summary
A number of topological materials, such as topological insulators [1,2,3] and topological semimetals [4,5], have been found by various theoretical and experimental approaches. Both in the topological insulator phases and in the topological semimetal phases, band inversions in the k space are required. It is sometimes difficult to design systems with band inversion, spinless systems, i.e., systems with negligible spin-orbit coupling. It is because there are almost no criteria for a systematic search for topological materials in spinless systems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
