ELECTRON SPIN-ECHO (ESE) INVESTIGATIONS OF CRITICAL PARAMAGNETIC RELAXATION ANOMALIES IN X-IRRADIATED TRIGLYCINE SULFATE (TGS-X)

The relaxation behaviour of a stable free radical in X‐irradiated triglycine sulphate is investigated by means of the electron spin‐echo method in the vicinity of the ferroelectric phase transition. A critical behaviour of the transverse relaxation as well as of the longitudinal relaxation is detected. The critical shortening of the phase memory time TM can be explained by the order parameter fluctuations at the phase transition of TGS. To the contrary the spin–lattice relaxation time T1 critically increases at the phase transition. This unusual behaviour cannot be understood on the basis of a direct interaction with the order parameter fluctuations via direct relaxation processes but points at a coupling of the acoustic lattice modes to the ferroelectric relaxational mode. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA