Computational design of flexible electrides with nontrivial band topology

Abstract

Electrides, with their excess electrons distributed in crystal cavities playing the role of anions, exhibit a variety of unique electronic and magnetic properties. In this work, we employ the first-principles crystal structure prediction to identify a new prototype of A3B electride in which both interlayer spacings and intralayer vacancies provide channels to accommodate the excess electrons in the crystal. This A3B type of structure is calculated to be thermodynamically stable for two alkaline metals oxides (Rb3O and K3O). Remarkably, the unique feature of multiple types of cavities makes the spatial arrangement of anionic electrons highly flexible via elastic strain engineering and chemical substitution, in contrast to the previously reported electrides characterized by a single topology of interstitial electrons. More importantly, our first-principles calculations reveal that Rb3O is a topological Dirac nodal line semimetal, which is induced by the Rb-s → O-p band inversion at the general electronic k momentums in the Brillouin zone associated with the intersitial electric charges. The discovery of flexible electride in combining with topological electronic properties opens an avenue for electride design and shows great promises in electronic device applications. arXiv:1811.11334v2 [cond-mat.mtrl-sci]

Computational Discovery of Inorganic Electrides from an Automated Screening

“…Magnetic electrides were reported in inorganic materials as well 14,20,21 . More recently, it has been suggested that electrides are suitable for achieving various topological phases in condensed matter physics, such as Y 2 C 22,23 , Sc 2 C 23 , Sr 2 Bi 23 , Ca 3 Pb 24 , Cs 3 O/Ba 3 N 25 and Rb 3 O 26 . Pressure has also proved to be an effective means to advance the electride research.…”

Six-fold Excitations in Electrides

“…Because of the potential candidates of various topological states, electrides have received growing attention recently [42]. Electrides Y 2 C [43,44], alkaline metal oxides [45] and Sr 2 Bi [46] are predicted to be nodal-line semimetals. HfBr is a 3D topological insulator [44], while ferromagnetic LaCl and GdCl are nodal-line semimetal and quantum anomalous Hall insulator [47], respectively.…”

Application of topological quantum chemistry in electrides

“…The low work function of electride is beneficial to induce band inversion, and to realize the nontrivial band topology [14]. Recently, the concept of electrides with nontrivial band topology has attracted much attention for promising applications in quantum devices [14,[23][24][25][26][27]. Given the close relation between BRs and orbital characters, TQC may shed light on the origin of electrides in ionic materials.…”