Muon Spin Relaxation Investigation of the Spin Dynamics of Geometrically Frustrated Antiferromagnets Y2Mo2O7 and Tb2Mo2O7 Static Critical Behavior of the Spin-Freezing

摘要

The spin dynamics of geometrically frustrated pyrochlore antiferromagnetsY2Mo2O7 and Tb2Mo2O7 have been investigated using muon spin relaxation. Adramatic slowing down of the moment fluctuations occurs as one approaches thespin freezing temperatures (TF=22 K and 25 K respectively) from above. Below TFthere is a disordered magnetic state similar to that found in a spin glass butwith a residual muon spin relaxation rate at low temperatures. These resultsshow that there is a large density of states for magnetic excitations in thesesystems near zero energy.