Electronic Structure Reorganization in MPS ₃ via d‐Shell‐Selective Alkali Metal Doping

ABSTRACT Semiconducting two‐dimensional (2D) antiferromagnetic (AFM) transition‐metal thiophosphates (MPS ₃ ) offer promising opportunities for spintronic applications due to their highly tunable electronic properties. While alloying and intercalation have been shown to modulate ground states, the role of d‐shell filling in governing these transitions remains insufficiently understood. Here, we investigate electron doping effects in MPS ₃ using angle‐resolved photoemission spectroscopy (ARPES), X‐ray photoelectron spectroscopy (XPS), and density functional theory (DFT+U). Lithium and cesium deposition are employed to induce doping across different MPS ₃ compounds. We identify two distinct doping mechanisms: in MnPS ₃ , electrons are primarily donated to the P ₂ S ₆ ligand clusters, with negligible Mn 2p core‐level shifts and no major changes in the valence band. In contrast, FePS ₃ , CoPS ₃ , and NiPS ₃ exhibit clear reductions in transition‐metal oxidation states, with a ∼1.0 eV reduction in spin‐orbit splitting for Co upon doping. ARPES on CoPS ₃ reveals a ∼400 meV shift of Co‐derived bands toward higher binding energies and new dispersive states up to 1 eV above the valence band maximum, indicating metallic behavior. These results establish a direct correlation between d‐shell filling and doping response, highlighting alkali metal doping as a tunable route to tailor the electronic and magnetic properties of 2D AFM semiconductors for spintronic applications.