Solution-processable Fe-doped SnSe₂ flakes with tunable morphology and robust near-room-temperature ferromagnetism

SnSe₂ has emerged as a promising host for van der Waals (vdW) magnetic semiconductors, yet the realization of robust near-room-temperature ferromagnetism via scalable solution-based synthesis remains a significant challenge. Here, we report low-cost polymer-assisted deposition (PAD) of Fe-doped SnSe₂ flakes exhibiting tunable morphology and strong ferromagnetic ordering up to ∼300 K. Undoped SnSe₂ exhibits distinctive snowflake-like fractal architectures consistent with diffusion-limited aggregation, which gradually evolves toward compact platelets upon Fe incorporation, revealing a direct correlation between the dopant level and morphological control. Magnetic characterization reveals that all Fe-doped samples are ferromagnetic, with the 5% Fe composition delivering the highest saturation magnetization and Curie temperature of about 300 K. Comprehensive spectroscopic and magnetic analyses reveal that the observed ferromagnetism arises from a hole-mediated exchange interaction, in which high-spin Fe²⁺ ions substituting for Sn⁴⁺ sites simultaneously provide localized magnetic moments and holes. This work establishes PAD as a versatile scalable platform for high-Curie-temperature vdW magnets and highlights the critical interplay of morphology, defects, and doping in tailoring spin functionality in layered semiconductors for next-generation spintronics.