Magnetic Weyl semimetals with diamond structure realized in spinel compounds
Wei Jiang, Huaqing Huang, Feng Liu, Jian‐Ping Wang, Tony Low
Abstract
We discover an ${e}_{g}$-orbital (${d}_{{z}^{2}},{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$) model within the diamond lattice (${e}_{g}$-diamond model) that hosts novel topological states. Specifically, the ${e}_{g}$-diamond model yields a three-dimensional (3D) nodal cage (3D-NC), which is characterized by a $d\ensuremath{-}d$ band inversion protected by two types of degenerate states (i.e., ${e}_{g}$-orbital and diamond-sublattice degeneracies). We demonstrate materials realization of this model in the well-known spinel compounds ($A{B}_{2}{X}_{4}$), where the tetrahedron-site cations ($A$) form the diamond sublattice. An ideal half metal with one metallic spin channel formed by well-isolated and half-filled ${e}_{g}$-diamond bands, accompanied by a large spin gap (4.36 eV) is discovered in one 4-2 spinel compound (${\mathrm{VMg}}_{2}{\mathrm{O}}_{4}$), which becomes a magnetic Weyl semimetal when spin-orbit coupling effect is further considered. Our discovery greatly enriches the physics of diamond structure and spinel compounds, opening a door to their application in spintronics.