Spin dynamics in geometrically frustrated antiferromagnetic pyrochlores

Abstract

We have studied the spin dynamics of several antiferromagnetic pyrochloreoxides. These magnets are geometrically frustrated and only reach their groundstates at temperatures much lower than that expected from mean field theory.Here we present data on the magnetic nature, especially the spin dynamics ofTb2Ti2O7,Gd2Ti2O7 and Y2Mo2O7. In these systems the ground states are found to be very different.Y2Mo2O7 freezes completely into a spin glass-like state,Tb2Ti2O7 is a cooperative paramagnetic and remains dynamic down to 15 mK andGd2Ti2O7 enters a unique partially ordered state at K.