Mg3X2 (X = C, Si) monolayer in a honeycomb-kagome lattice: A global minimum structure

Abstract Two stable Two-dimensional (2D) material with a hexagonal honeycomb structure, i.e., the Mg 3 X 2 (X = C, Si) monolayer have been predicted using a newly developed particle swarm optimization algorithm based on first-principles calculations. We found that the Mg 3 X 2 exhibit a Dirac feature which arises from the p z orbitals of Mg and X atoms under the nonmagnetic (NM) state. The Dirac cone are not affected by stress strains along both the x and y directions. After considering the magnetic configuration, the ground state of Mg 3 X 2 is antiferromagnetic (AFM) state. This magnetic configuration breaks the Dirac feature and causes a sizeable band gap in Mg 3 X 2 monolayer. The newly predicted Mg 3 X 2 is both mechanically and dynamically stable, implying its experimentally synthetic feasibility. The results are beneficial to this new 2D material in applications and providing a feasible strategy for 2D materials design.