Relaxation and aging in lattice glasses

A sequential relaxation model for the susceptibility of site-diluted Ising systems is described. It is shown that the model, which yields an excellent fit to experimental results for the real part of the ac susceptibility of the site-diluted two-dimensional Ising spin glass, Fe0.4Mg0.6Cl2, predicts a change in susceptibility with time during aging that is confirmed by experiments on other spin glasses and the orientational glass KBr0.5CN0.5.