Spiral spin liquid correlations in diamond antiferromagnets

We have introduced a simple model for frustrated magnetism on a diamond lattice, appropriate for a number of recently studied normal spinel materials. The model possesses a massive degeneracy of coplanar spin spiral states, characterized by propagation wavevectors that reside on a two-dimensional surface in momentum space. The degeneracy of low energy states significantly suppresses the ordering temperature relative to the Curie-Weiss temperature $\Theta_{CW}$. In the intermediate temperature regime $T_c