Neutron scattering studies of geometrically frustrated pyrochlore antiferromagnets

Elastic and inelastic neutron scattering work on the cubic pyrochlore antiferromagnets Y2Mo2O7, Tb2Ti2O7, and Tb2Mo2O7 is reviewed. These materials are characterized by antiferromagnetically coupled moments residing on a network of corner-sharing tetrahedra. Geometrical frustration manifests itself strongly in such systems in that two of them display a spin-glass-like transition in the apparent absence of chemical disorder, while the other remains paramagnetic to at least 0.1 K, despite developing antiferromagnetic short-range order at 50 K.