Functional Indium Vacancies in Indium Phosphors Chalcogenides.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Layered Indium phosphorus trichalcogenides (In4/3P2X6) are known for ordered indium vacancies and stacking-dependent properties.
• Applications in electronics, catalysis, and energy storage are hindered by elusive vacancy-governed structures and challenging visualization.

Purpose of the Study:

• To systematically explore the atomic structure of In4/3P2X6 using advanced microscopy and theory.
• To investigate the magnetic properties of doped In4/3P2X6 and their potential for novel 2D magnets.

Main Methods:

• Low-dose aberration-corrected scanning transmission electron microscopy (STEM).
• Four-dimensional STEM (4D-STEM) techniques.
• Density functional theory (DFT) calculations.

Main Results:

• Atomic-scale resolution of indium vacancies with glide-reflection symmetric ordering in In4/3P2X6.
• Identification of armchair-type and zigzag-type interlayer gliding, leading to ABC and nearly-ABC stacking polytypes.
• DFT confirmed energetically favorable gliding modes driven by ligand-modulated charge distributions.
• Doping induced tunable magnetic ordering, structural transition to MPX3-like phase, and paramagnetic (PM)-FM transition.

Conclusions:

• Vacancy ordering dictates the atomic structure and stacking polytypes in In4/3P2X6.
• Doping engineering of In4/3P2X6 offers a promising route for designing novel functional 2D magnets.