Advances in electronic structure and magnetic properties of two-dimensional hexagonal lattice transition metal trihalides

The successful preparation of graphene has opened a new era of two-dimensional(2D) materials research.A large number of studies have shown that two-dimensional materials have unique physical and chemical properties in force, heat, light, electricity, and other aspects, and have potential application value in optoelectronic devices, data storage, and spintronics. However, most 2D materials are non-magnetic or weakly magnetic, and their low phase transition temperature and weak magnetic properties make it difficult for many 2D materials to meet the standards for practical applications. Recent studies have found that single-layer MX3with a hexagonal lattice structure( M is transition metal atom, X is halogen atom) has robust and tunable magnetic properties, and is a class of candidate materials with great research value. In this paper, the electronic characteristics and magnetic properties of some hexagonal 3d transition metal trihalides are reviewed, with emphasis on the analysis of the magnetic coupling mechanism in the magnetic system, and the relevant work on the external regulation of these systems is summarized. The paper examines various methods to regulate the electronic structure, magnetic properties, and phase transition temperature of MX3thin films, such as applying strain, atom doping or substitution, alloying, and constructing spatially asymmetric Janus structures. Finally, the current challenges and future development prospects of MX3thin films are discussed.