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.