Alloys of CoI₂ Nanoclusters Embedded in the PbI₂ Lattice Exhibiting High-Temperature Hysteretic Paramagnetic Transitions and Low-Temperature Diverse Magnetic Short-Range Ordering

Dilute magnetic semiconductors (DMSs) are crucial for various spintronic and magneto-optical applications, typically created by doping d- or f-orbital-based metal ions into wide bandgap nonmagnetic semiconductors. In this study, we synthesized Pb_1-xCo_xI₂ (x = 0.05-0.14) alloys by doping PbI₂ with Co²⁺ ions using a simple mechanochemical method and characterized their morphology, structure, thermal stability, and magnetic properties. The Co²⁺ ions in the alloys formed CoI₂ clusters with dimensions less than 10 nm, homogeneously distributed within the PbI₂ lattice. These alloys exhibited a paramagnetic phase transition with a thermal hysteresis loop at high temperatures (>370 K) and Co²⁺-content-dependent magnetic short-range ordering behaviors (spin glass, cluster glass, or superparamagnetism) at low temperatures (<15 K). The strong interactions between itinerant electrons and the localized 3d electrons of Co²⁺ ions indicate Pb_1-xCo_xI₂ alloys, with characteristic behaviors observed in DMSs. This study demonstrates that mechanochemical synthesis is a facile and efficient method for preparing alloys of van der Waals crystals, offering precise control over alloy composition, particularly when dealing with reaction systems involving components with different soft-hard acid-base properties.