NONLINEAR SUSCEPTIBILITY MEASUREMENTS AT THE SPIN-GLASS TRANSITION OFTHE PYROCHLORE ANTIFERROMAGNET Y2MO2O7

We have measured the magnetic held and temperature dependence of the n onlinear de susceptibility, chi(nl), of the frustrated pyrochlore anti ferromagnet Y2Mo2O7 close to and above the temperature, T-g similar to 22 K, where this material exhibits irreversible (spin-glass like) mag netic behavior Our results suggest that the observed irreversible magn etic properties in this material ate due to a thermodynamic spin-glass transition signaled by a divergence of the nonlinear magnetic suscept ibility coefficient chi(3) similar to(T/T-g-1)(-y) at T-g with y=3.3+/ -0.5. chi(nl) shows two power-law behavior at T-g, chi(nl)similar to H -2/delta, with delta similar to 2.8 for H<1000 Oe and delta similar to 4.1 for H>2000 Oe. These values for gamma and delta, as well as the c rossover behavior of chi(nl), at T-g, is consistent what is found in c ommon disordered Heisenberg spin glass materials. (C) 1996 American In stitute of Physics.