Ab initio study on the possible magnetic topological semimetallic state in MnMg$_{2}$O$_{4}$}

Satoshi Tomita, DaPeng Yao, Hiroki Tsuchiura, Kentaro Nomura

We study the electronic state of an inverse spinel compound MnMg$_{2}$O$_{4}$
based on first-principles calculations. The high-spin state is realized in Mn
ions on the diamond lattice, resulting in that this material is found to be a
half-metallic semimetal with the minority spin-gap about 3eV, and also with
line nodes in the Brillouin zone. The intrinsic anomalous Hall conductivity
(AHC) is also computed as a function of the chemical potential of the system
assuming the rigid band structure, and is found to exhibit a peak structure
with a maximum value of 200 S/cm at only 15 meV above the Fermi level. The
relation between the large AHC and Berry curvature in the Brillouin zone is
also discussed.