Two-Dimensional Magnetic Anionic Electrons in Electrides: Generation and Manipulation.

Introducing magnetism to anionic electrons (AE) of electrides, especially for those confined in two-dimensional (2D) interlayer spaces, could provide a promising way to generate 2D spin-polarized free electron gas. However, the realization of this is challenging. Here, we propose a strategy for generating 2D magnetic AE, which requires two fundamental criteria, i.e., coexistence of localized AE (LAE) and delocalized AE (DAE) and a nearly half-filled LAE. Applying this to Y2C, the magnetism of 2D AE is tunable or sensitive to external strain, hole doping, and layer thickness, depending on the competition between atomic-orbital electrons, DAE, and LAE. Remarkably, a reversible on/off switching of magnetism can be achieved in bilayer Y2C by an electric field. Furthermore, the 2D magnetic AE in Y2C thin films are more robust against oxidation due to spatially selective hole doping effects. The manipulation of spin-polarized 2D AE gas paves a new way for designing spintronic devices with van der Waals magnets.