Dirac Nodes and Magnetic Order in M ₂ X ₂ Transition-Metal Chalcogenides

In this study, we perform a computational analysis of the M₂X₂ transition-metal chalcogenides (TMCs). Using density functional theory with a spin-polarized generalized gradient approximation, we examine the magnetic and electronic properties for the antiferromagnetic and ferromagnetic states with M = Cr, Mn, and Fe and X = S and Se. After optimizing the geometric structure for stability, we examine the spin-polarized electronic structure, density of states, and Mulliken population. It is discovered that these materials are quasi-two-dimensional honeycomb lattices with metallic antiferromagnetic ground states. The structures consist of a distorted tetrahedral crystal-field symmetry that has a distinct magnetic moment. An analysis of the electronic structure shows the presence of nodal points that resemble Dirac nodes for all cases, which leads to the possibility of the realization of magnetic Dirac materials.