Power-law decay in first-order relaxation processes

Starting from a simple definition of a stationary regime in first-order relaxation processes, we obtain that experimental results are to be fitted to a power law when approaching the stationary limit. On the basis of this result, we propose a graphical representation that allows the discrimination between power-law and stretched exponential time decays. Examples of fittings of magnetic, dielectric, and simulated relaxation data support the results.