RELATIONS BETWEEN THE PARISI PHYSICAL ORDER-PARAMETER AND AC MAGNETIC-SUSCEPTIBILITY IN SPIN-GLASSES

The consequences of a hierarchical model for barrier heights between m etastable states are explored. We show that the Parisi physical order parameter P(q) extracted from the equilibrium out-of-phase susceptibil ity, is consistent with previous dc measurement of P(q). The dynamic s usceptibility chi ''(omega, t) before and after a dc magnetic field ch ange is obtained by introducing a reduction of barrier heights by the relative Zeeman energy change E-Z, the reduction increasing for increa sing barrier height. This results in the correct frequency dependence for the observed jump in chi ''(omega) upon a change in magnetic field . Measurement of these jumps over a wide range of waiting times serves as a vehicle for the determination of excitation barrier response to a magnetic field change.