Stacking-sequence-independent band structure and shear exfoliation of two-dimensional electride materials

摘要

The electronic band structure of crystals is generally influenced by theperiodic arrangement of their constituent atoms. Specifically, the emergingtwo-dimensional (2D) layered structures have shown different band structureswith respect to their stacking configurations. Here, based on first-principlesdensity-functional theory calculations, we demonstrate that the band structureof the recently synthesized 2D Ca$_2$N electride changes little for thestacking sequence as well as the lateral interlayer shift. This intriguinginvariance of band structure with respect to geometrical variations can beattributed to a complete screening of [Ca$_2$N]$^{+}$ cationic layers byanionic excess electrons delocalized between the cationic layers. The resultingweak interactions between 2D dressed cationic layers give rise to not only ashallow potential barrier for bilayer sliding but also an electron-dopingfacilitated shear exfoliation. Our findings open a route for exploration of thepeculiar geometry-insensitive electronic properties in 2D electride materials,which will be useful for future thermally stable electronic applications.