Synergetic effects of combining TM single- and double-atom catalysts embedded in C₂N on inducing half-metallicity: DFT study

Designing 2D-materials that exhibit half-metallic properties is crucially important in spintronic devices that are used in low-power high-density logic circuits. The large pores in the C₂N morphology can stably accommodate various configurations of transition-metal (TM) atoms that can lead to ferromagnetic (FMC) and anti-ferromagnetic coupling interactions among them, and thus paving the way for achieving half-metallic characteristics. In the present study, we use manganese ‘Mn’ as a promising catalyst and the spin-polarized density-functional theory to search for suitable configurations of metal atoms that yield half-metallicity. Test samples comprised of single-atom catalyst (SAC) and double-atom catalyst (DAC) of Mn embedded in a C₂N sample of size 2 × 2 primitive cells as well as their combinations in neighboring large pores (i.e. SAC-SAC, SAC-DAC, and DAC-DAC). Tests were extended to screen many other TM catalysts and the results showed the existence of half metallicity in just five cases: (a) C₂N:Mn (DAC, SAC-SAC, and SAC-DAC); (b) C₂N:Fe (DAC); and (c) C₂N:Ni (SAC-DAC). Our results further showed the origins of half-metallicity to be attributed to FMC interactions between the catalysts with the six mirror images, formed by the periodic-boundary conditions. The FMC interaction is found to have strength of about 20 meV and critical length scale up to about ∼21-29 Å, dependent on both the type of magnetic impurity and the synergetic effects. The potential relevance of half-metallicity to spintronic device application is discussed. Our theoretical results have been benchmarked to the available data in literature and they were found to be in good agreements.