Spin freezing in the geometrically frustrated pyrochlore antiferromagnet Tb2Mo2O7

The magnetic metal ions in the cubic pyrochlore Tb2Mo2O7 form an infinite three-dimensional network of corner-sharing tetrahedra with a very high potential for frustration in the presence of antiferromagnetism. We have performed neutron scattering measurements which show short-range spatial correlations that develop continuously with decreasing temperature, while the characteristic time scale for the fluctuating moments decreases dramatically below Tf∼25 K. Therefore, this pure material, which possess frustration that is purely geometrical in origin, displays a spin-glass state at low temperatures.