Thickness-Dependent Crystal Structure, Synthesis, and Magnetism of Thin Film Chromium Chalcogenides: A Review

In the search for two-dimensional (2D) magnets operating under ambient conditions, quasi-2D non-van der Waals (vdW) materials have attracted considerable research interest over the last five years. In addition to their high Curie temperature (TC), their superior air stability to that of vdW 2D magnets has made them potential candidates for future room-temperature spintronics applications. Furthermore, recent progress in the thickness-dependent crystal lattice and magnetic properties of non-vdW Cr2X3 (X = S, Se, or Te) has brought them to areas that are once set aside for 2D vdW magnets in fundamental research and applications. Despite covalent bonding between magnetic layers, various bottom-up synthesis methods produced thickness-controlled flakes of Cr2X3. Moreover, layer-dependent structural and magnetic properties are among the novel research directions in these materials. This review systematically summarizes recent studies on Cr2X3 crystal structure, their controllable synthesis, and their respective magnetic properties. A summary of some significant results on thickness-controlled synthesis in Cr2X3 and thickness-dependent magnetism in Cr2Te3 is presented. Additionally, experimental and theoretical reports are presented to explain interlayer magnetic interaction. The work reveals the interaction between synthesis, structure, and magnetism. Finally, future research directions of new Cr2X3-based materials, rich magnetism in Cr2X3, and their potential application are discussed.