Anisotropic exchange and noncollinear antiferromagnets on a noncentrosymmetric fcc half-Heusler structure

One of the signatures face-centered cubic (fcc) antiferromagnet as a typical example geometrically frustrated system is large ground state degeneracy classical nearest neighbor and next-nearest Heisenberg (isotropic) model on this lattice. In particular, collinear states are degenerate with non-collinear non-coplanar ones: accidental expected to be lifted by anisotropic exchange interactions. work, we derive most general allowed space-group symmetry noncentrosymmetric half-Heusler compounds, which includes three terms: so-called Kitaev, Gamma Dzyaloshinskii-Moriya interactions -- notably, latter breaking inversion in these materials has not been previously studied context fcc We compute resulting phase diagram show how different terms lift isotropic model, lay emphasis finding regimes where multi-q (non-collinear/non-coplanar) selected anisotropy. then discuss role quantum fluctuations coupling magnetic field selection, that effects can stabilize (triple-q) states. These results suggest some antiferromagnets might host rare non-collinear/non-coplanar orders, may turn explain unusual transport properties detected semimetals.