Mean-field approach to magnetic ordering in highly frustrated pyrochlores

The metal atoms in the pyrochlore system of compounds (A2B2O7, where A and B are metals) form an infinite three-dimensional network of corner-sharing tetrahedra with cubic symmetry. For antiferromagnetic nearest-neighbor interactions and only B atoms magnetic, there is a very high degree of frustration, and no long-range order is predicted in the absence of further neighbor interactions. A general form of the mean-field theory is developed for …