Spin superstructure and noncoplanar ordering in metallic pyrochlore   magnets with degenerate orbitals
  We study double-exchange models with itinerant t2g electrons in spinel and pyrochlore crystals. In both cases the localized spins form a network of corner-sharing tetrahedra. We show that the strong directional dependence of t2g orbitals leads to unusual Fermi surfaces that induce spin superstructures and noncoplanar orderings for a weak coupling between itinerant electrons and localized spins. Implications of our results to ZnV2O4 and Cd2Os2O7 are also discussed. 
Gia-Wei Chern and Cristian D. Batista
cond-mat.str-el cond-mat.mtrl-sci