Neutron spin echo study of spin glass dynamics (invited)

The neutron spin echo technique allows us to obtain direct, model independent information on spin relaxation in the time domain of 3×10−12 to 3×10−9 sec. The experimental results on a variety of spin glass samples reveal a number of common characteristic features. Namely (a) the relaxation kinetics correspond to a broad distribution of relaxation times; (b) the slowing down of the relaxation can be described by an Arrhenius law above the freezing temperature, but not around and below; (c) the absence of momentum dependence in the relaxation dynamics indicates that nonexchange type interactions play a fundamental role in this dynamics.