Stacking induced symmetry broken and gap opening in Dirac half-metal MnF3

Abstract

Two-dimensional ferromagnetic materials have a broader development prospect in the field of spintronics. In particular, the high spin polarization system with half-metallic characteristics can be used as an efficient spin injection electrode. By first-principles calculation, we predict that monolayer MnF3 has Dirac half-metallic properties. The formation mechanism of this Dirac half-metallic state is mainly attributed to the local symmetry of magnetic Mn3+ in the sublattice. It is interesting to note that the local symmetry of can be broken in bilayer MnF3 through different stacking configurations. Therefore, bilayer MnF3 with different stacking models are established, and the calculation of their magnetic ground states shows that all the systems maintain a ferromagnetic ground state. The AA-stacking holds the symmetry and Dirac electronic states. Under the interfacial coulomb repulsion, the Dirac electronic states of the top layer and bottom layer of MnF3 are shifted relative to each other and overlap to form a nodal-ring state. Interestingly, in AB-stacking model, the inversion symmetry exists, while the sublattice symmetry of Mn is broken, resulting in the different orbital filling of Mn and forming a large insulating gap (732.2 meV). Additionally, the inversion symmetry of the system is broken in AC-stacking, while the intralayer sublattice symmetry is preserved. Therefore, under the effect of inversion symmetry broken, the Dirac electronic states of both top and bottom layer MnF3 will have a small gap opening (24.6 meV). The topological properties of all three systems have been analyzed. Based on the above research results, it can be realized to regulate the electronic states of the system by changing the stacking model between 2D magnetic homostructure, which provides an ideal platform for the design and development of spin logic devices.