STRETCHED-EXPONENTIAL APPROACH IN RELAXING SYSTEMS

The stretched-exponential or Kohlrausch-Williams-Watts function has be en widely used in the description of a large variety of relaxation phe nomena in condensed matter physics. In this work, we consider this app roach as a fun damental law and extend its applicability range to ther mally activated relaxation processes. A non-iterative and robust techn ique is developed in order to obtain the characteristic parameters of this type of phenomena. The method is based on a set of closed-form ex pressions for the amplitude, activation energy, pre-exponential factor and stretched-exponent that can be directly computed from isothermal curves. This strategy is applied to describe the magnetic disaccommoda tion spectra observed around room temperature in a magnetite sample.