Realizing half-metallicity in K2CoF4 exfoliated nanosheets via defect engineering.

Two-dimensional (2D) materials with intriguing electronic characteristics open up tremendous opportunities for application in future nanoelectronic devices, and have become one of the hot subjects of today's research. Here, we firstly predict the possibility of realizing a 2D exfoliated ionic bonding nanosheet, namely the K2CoF4 nanosheet, based on first-principles calculations. Through analysis of the cleavage energy, in-plane stiffness and stability, the free-standing K2CoF4 nanosheet can be exfoliated in experiments. It is shown that the K2CoF4 nanosheet with K vacancy can transform into a ferromagnetic half-metal under moderate tensile strain, whereas the pristine K2CoF4 nanosheet is an antiferromagnetic semiconductor. Monte Carlo simulations based on the Heisenberg model predict that the Curie temperature for the K vacancy K2CoF4 nanosheet under 2% tensile strain is higher than room temperature. Therefore, our results suggest that the K2CoF4 nanosheet may be a promising material for spintronic and nanoelectronic applications.