OPTICAL STUDY OF TIME-VARIATION OF MEMORY EFFECT IN INCOMMENSURATE PHASE OF QUARTZ

New observations of the memory effect in the incommensurate phase of q uartz have been performed with birefringence measurements. The enhance ment and the decay of the memory effect have been measured for various writing times. A linear relationship between the decay time and the w riting time has been found, which cannot be explained by the usual dif fusion model of the memory effect. We also present the first observati on of a memory effect in a light scattering experiment.