Scaling of the magnetic response in doped antiferromagnets

A theory of the anomalous $\omega/T$ scaling of the dynamic magnetic response in cuprates at low doping is presented. It is based on the memory function representation of the dynamical spin suceptibility in a doped antiferromagnet where the damping of the collective mode is constant and large, whereas the equal-time spin correlations saturate at low $T$. Exact diagonalization results within the t-J model are shown to support assumptions. Consequences, both for the scaling function and the normalization amplitude, are well in agreement with neutron scattering results.