DYNAMIC SUSCEPTIBILITY FOR ISING-SPIN CLUSTERS IN RANDOM-FIELDS

The dynamic susceptibility for a cluster of six coupled random field I sing spins in two different distributions, binary (ED) and Gaussian (G D), are calculated and exact results are obtained. The real and imagin ary parts of the dynamic susceptibility display maxima when plotted ve rsus temperature. These maxima can be described by an Arrhenius law. I f the logarithm of the susceptibilities is plotted as a function of th e logarithm of frequency and if the clusters are frustrated, then the real part displays a sequence of plateau regions and the imaginary par t has a sequence of maxima in weak random fields. In the ED case of ra ndom field for large amplitudes there is only one plateau and one corr esponding maximum as in ferromagnetic (FM) and paramagnetic (PM) cases . Our results confirm that any weak random field spill turn out to des troy the ordered state and random field Ising-spin clusters behave lik e Ising-spin glasses.