Towards predictive models of transition metal intercalation - A study of non-dilute Iron diffusion in 2H-TaS2

2D magnets have many applications in ultralow-power electronics owing to their unparalleled optical adressibility, however relatively few stable candidates have been identified to date. Atomically thin, magnetically doped transition metal dichalcogenides are a promising new class of 2D magnets, in which magnetism originates from chemical dopants instead of the host lattice. However as synthetic routes relying on chemical intercalation have been recently proposed, the intercalation dynamics in these materials is not yet understood. We investigate iron diffusion in atomically thin 2H-TaS2 using first principles calculations. To estimate the diffusive behavior, we construct an on-lattice diffusion model to calculate the diffusion constants at a set of characteristic temperatures and intercalation densities using Kinetic Monte Carlo. We fit the interaction between octahedrally coordinated sites to a pairwise form and evaluate the diffusion barrier for itinerant cations using the nudged elastic band method. Our results suggest that the iron migration proceeds through a tetrahedrally coordinated intermediate similar to lithium diffusion in TiS2 and, notably, that the diffusion barrier depends on the spin state of the iron with potential ramifications for field-controlled intercalation.