Cutting-Edge Advances in Ferroic Few-Layer Group IV Monochalcogenides and Their Future Technological Applications

Eco-friendly and earth-abundant Group IV monochalcogenides (MX), in their monolayer and few-layer forms, have emerged as promising multiferroic materials exhibiting both ferroelectric and ferroelastic properties at room temperature. In their bulk and stable phase, these materials are stacked in an antiferroelectric configuration, designated as AB, which results in the loss of ferroelectricity and second-harmonic generation (SHG). Recent investigations into a new ferroelectric stacking arrangement, called AC stacking, have further enhanced the potential of these 2D materials, making them promising candidates for future nanotechnological innovations, including miniaturized photonics and advanced optoelectronic devices. This review presents a comprehensive overview of the latest advancements in the synthesis of few-layer MX, covering both top-down methods (e.g., mechanical exfoliation, liquid-phase exfoliation, and etching) and bottom-up techniques (e.g., chemical vapor deposition (CVD) and physical vapor deposition (PVD)). Additionally, it explores their structural characteristics and different stacking configurations, highlighting recent studies on SHG and third harmonic generation (THG). Furthermore, the latest investigations into the ferroelectric properties of MX are examined, along with their promising applications in 2D material-based technologies.