Theory of the Neutron Scattering Cross Section in Spin-Glasses

Using mean-field theory we compute the frequency-integrated neutron cross section $I(q,T)\mathrm{}$ for spin-glasses. We find, as observed experimentally, that the temperature of the maximum of $I(q,T)\mathrm{}$ depends on the momentum transfer $q$ and is different from the freezing temperature $T_c$ at which the susceptibility $\chi \mathrm{}(q,T)\mathrm{}$ has a cusp. These results suggest that recent neutron scattering experiments are consistent with a sharp phase transition at a single temperature $T_c$ in spin-glasses.