The dynamical-excitation spectrum of a diluted antiferromagnet is studied in the effective-medium approximation. Recent results based upon this approximation are revised and a detailed analysis of the structure factor for neutron scattering is carried out and evaluated numerically. The spectrum reveals a sharp crossover from extended to localized excitations at a crossover frequency, c(p-pc)3/2, where p is the percolation concentration and pc is the percolation threshold of the diluted antiferromagnet. The results are compared with recent neutron-diffraction experiments and with the scaling model for fractons.
ASJC Scopus subject areas
- Condensed Matter Physics