Dynamic Properties of a Diluted Pyrochlore Cooperative Paramagnet(TbpY1−p)2Ti2O7

Investigations of the spin dynamics of the geometrically frustrated pyrochlore (Tb p Y 1 - p ) 2 Ti 2 O 7 , using muon spin relaxation and neutron spin echo, as a function of magnetic coverage p, have been carried out Our major finding is that paramagnetic fluctuations prevail as T → 0 for all values of p, and that they are sensitive to dilution, indicating a cooperative spin motion. However, the percolation threshold p c is not a critical point for the fluctuations. We also find that the low temperature spectral density has a 1/f behavior, and that dilution slows down the spin fluctuations.