Berry Phase and Exchange Contributions in Antiskyrmion Hosting Heusler Compound Mn_1.5XY

Recently, the Heusler compounds Mn_1.4PtSn and Mn_1.4Pt_0.9Pd_0.1Sn were shown to stabilize an antiskyrmion lattice above room temperature. This Heusler compound forms in a superstructure with the D_2d symmetry, which allows for an anisotropic Dzyaloshinskii-Moriya interaction (DMI) perpendicular to the tetragonal axis. We use density functional theory calculations of Mn_1.5XY to extract the relevant exchange interactions that determine the rich phase diagrams in these materials. The exchange interactions are between the large moments on the Mn atoms ~4 μ_B, which show magnetic states that are non-collinear ferrimagnetic up to the spin reorientation. The major role of the DMI and anisotropy are due to the X ion, either Rh, Pd, Ir, or Pt which also influence the exchange interactions. The Fermi level can be tuned by the Y ion, either In, Sn or Sb. We last calculate the anomalous Hall effect and topological Hall effects in these regimes, to capture the influence of the electronic structure on the Berry curvature.