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

Sui, Xuelei; Wang, Jianfeng; Yam, ChiYung; Huang, Bing · Nano Lett · 2021

basic_science · Level V

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Abstract

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 Y<sub>2</sub>C, 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 Y<sub>2</sub>C by an electric field. Furthermore, the 2D magnetic AE in Y<sub>2</sub>C 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.