Ferromagnetic and Half-Metallic FeC2 Monolayer Containing C2 Dimers.

Ferromagnetism and half-metallicity are two vital properties of a material for realizing its potential in spintronics applications. However, none of the two-dimensional (2D) pristine metal-carbide sheets synthesized experimentally exhibits half-metallicity with ferromagnetic coupling. Here, a ferromagnetic and half-metallic FeC2 sheet containing isolated C2 dimers rather than individual carbon atoms is predicted to be such a material. Based on state-of-the-art theoretical calculations, we show that the FeC2 sheet is dynamically, thermally, and mechanically stable and can be chemically exfoliated from the bulk phase of layered ThFeC2. Due to its unique atomic configuration, the FeC2 sheet exhibits ferromagnetism with a Curie temperature of 245 K. This is in contrast to its bulk counterpart, ThFeC2, which is paramagnetic. We also find that, unlike the metallic metal-carbide sheets, the FeC2 sheet is half-metallic with semiconducting spin-up and metallic spin-down channels. Moreover, half-metallicity can remain until an equi-biaxial strain of 10%. In addition, we provide the Raman and infrared spectra which can be used to identify this new 2D structure experimentally in the future.