Nonlinear susceptibility measurements at the spin-glass transition of the pyrochlore antiferromagnet Y2Mo2O7

We have measured the magnetic field and temperature dependence of the nonlinear dc susceptibility, χnl, of the frustrated pyrochlore antiferromagnet Y2Mo2O7 close to and above the temperature, Tg∼22 K, where this material exhibits irreversible (spin-glass like) magnetic behavior. Our results suggest that the observed irreversible magnetic properties in this material are due to a thermodynamic spin-glass transition signaled by a divergence of the nonlinear magnetic susceptibility coefficient χ3∼(T/Tg-1)^-γ at Tg with γ=3.3±0.5. χnl shows two power-law behavior at Tg, χnl∼H^2/δ, with δ∼2.8 for H<1000 Oe and δ∼4.1 for H>2000 Oe. These values for γ and δ, as well as the crossover behavior of χnl at Tg, is consistent what is found in common disordered Heisenberg spin glass materials. © 1996 American Institute of Physics.