Effective dynamic critical exponent for random uniaxial spin systems at marginal dimensionality

Abstract

The critical dynamics of a random uniaxial dipolar ferromagnet is studied for the range of temperatures tx<<t<<1, where tx is related to a degeneracy of the renormalisation-group scaling relations at leading order. The behaviour of the characteristic frequency is described by an effective dynamic critical exponent which is parametrised by the concentration of impurities.