Role of exchange splitting and ligand-field splitting in tuning the magnetic anisotropy of an individual iridium atom on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Ta</mml:mi><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> substrate
Shiming Yan, Wen Qiao, Deyou Jin, Xiaoyong Xu, Wenbo Mi, Dunhui Wang
Abstract
In this work, using first-principles calculation we investigate the magnetic anisotropy (MA) of single-atom iridium (Ir) on $\mathrm{Ta}{\mathrm{S}}_{2}$ 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 the spin-conservation term and the spin-flip term. The spin-conservation term is mainly generated by spin-orbit coupling (SOC) interaction on the ${d}_{xy}/{d}_{{x}^{2}\text{\ensuremath{-}}{y}^{2}}$ orbitals and is contributed to the out-of-plane MA. The spin-flip term is caused by SOC interaction on the ${d}_{xz}/{d}_{yz}$ 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 reduce the ligand-field splitting and enhance the exchange splitting, resulting in the enhancement of the out-of-plane MA from ${d}_{xy}/{d}_{{x}^{2}\text{\ensuremath{-}}{y}^{2}}$ orbitals and the reduction of the in-plane MA from ${d}_{xz}/{d}_{yz}$ and ${p}_{x}/{p}_{y}$ orbitals, hence leading to the change of the strength and direction of the total MA. Our study provides a way for tuning the MA of a single-atom magnet on 2D transition metal dichalcogenide substrate by control of the exchange splitting and the ligand-field splitting.