In this work, using first-principle calculation we investigate the magnetic anisotropy (MA) of single-atom iridium (Ir) on TaS 2 substrate. We find that the strength and direction of MA in the Ir adatom can be tuned by strain. The MA arises from two sources, namely spin-conservation term and spin-flip term. The spin-conservation term is generated by spin-orbit coupling (SOC) interaction on d xy /d x2-y2 orbitals and is contributed to the out-of-plane MA. The spin-flip term is caused by SOC interaction on d xz /d yz and p x /p y orbitals and is responsible for the in-plane MA. We further find that strain-tuned MA is mainly determined by exchange splitting and ligand field splitting. Increase of strain will enhance the exchange splitting and reduce the ligand field splitting, resulting in the enhancement of the in-plane MA from d xy /d x2-y2 orbitals and the reduction of the out-of-plane MA from d xz /d yz and p x /p y orbitals, and hence leading to the change of the strength and direction of the total MA. Our study provides a way for tuning the MA of single-atoms magnet on 2D transition metal dichalcogenides substrate by control of the exchange splitting and the ligand field splitting.
The d-band center descriptor based on the adsorption strength of adsorbate has been widely used in understanding and predicting the catalytic activity in various metal catalysts. However, its applicability is unsure for the single-atom-anchored two-dimensional (2D) catalysts. Here, taking the hydrogen (H) adsorption on the single-atom-anchored 2D basal plane as example, we examine the influence of orbitals interaction on the bond strength of hydrogen adsorption. We find that the adsorption of H is formed mainly via the hybridization between the 1s orbital of H and the vertical d z2 orbital of anchored atoms. The other four projected d orbitals (d xy /d x2-y2 , d xz /d yz ) have no contribution to the H chemical bond. There is an explicit linear relation between the d z2 -bandcenter and the H bond strength. The d z2 -band center is proposed as an activity descriptor for hydrogen evolution reaction (HER). We demonstrate that the d z2 -band center is valid for the single-atom active sites on a single facet, such as the basal plane of 2D nanosheets. For the surface with multiple facets, such as the surface of three-dimensional (3D) polyhedral nanoparticles, the d-band center is more suitable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.