Static critical behavior of the spin-freezing transition in the geometrically frustrated pyrochlore antiferromagnet Y2Mo2O7

Some frustrated pyrochlore antiferromagnets, such as Y2Mo2O7, show a spin-freezing transition and magnetic irreversibilities below a temperature T-f similar to what is observed in randomly frustrated spin-glasses. We present results of nonlinear de magnetization measurements on Y2Mo2O7 that provide strong evidence that there is an underlying thermodynamic phase transition at T-f, which is characterized by critical exponents gamma approximate to 2.8 and beta approximate to 0.8. These values are typical of those found in random spin-glasses, despite the fact that the level of random disorder in Y2Mo2O7 is immeasurably small.