Electronic Structure Reorganization in MPS₃ via d-Shell-Selective Alkali Metal Doping

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Two-dimensional (2D) antiferromagnetic (AFM) transition-metal thiophosphates (MPS3) are promising for spintronics.
• Tuning their ground states via alloying and intercalation is known, but the role of d-shell filling is unclear.

Purpose of the Study:

• Investigate electron doping effects in MPS3 compounds.
• Understand how d-shell filling influences electronic and magnetic properties.
• Explore alkali metal doping as a method to tailor 2D AFM semiconductors.

Main Methods:

• Angle-resolved photoemission spectroscopy (ARPES)
• X-ray photoelectron spectroscopy (XPS)
• Density functional theory (DFT+U) calculations
• Lithium and cesium deposition for alkali metal doping

Main Results:

• Two doping mechanisms identified: electron donation to ligand clusters (MnPS3) or reduction of transition-metal oxidation states (FePS3, CoPS3, NiPS3).
• Co doping in CoPS3 showed a ~1.0 eV spin-orbit splitting reduction and metallic behavior via ARPES.
• Observed ~400 meV shift of Co-derived bands and new dispersive states above the valence band maximum.

Conclusions:

• Established a direct correlation between d-shell filling and doping response in MPS3 materials.
• Alkali metal doping is a viable strategy for tuning the electronic and magnetic properties of 2D AFM semiconductors.
• Findings support the development of novel 2D materials for spintronic applications.