Spin systems in strongly correlated random fields

Abstract

An arbitrary spin system on a n-dimensional lattice in a strongly correlated random field is considered. The random field is assumed to take the same value at all lattice sites and in this limit it is shown that the quenched and annealed distributions of the random field are equivalent. This equivalence is in accordance with the result obtained by Falk for classical spin systems, and can be seen as its extension, in a particular case, for more general spin systems. A simple application is presented for the one-dimensional XY-model in a transverse random field.