Interaction of a Defect Density Wave With a Modulated Structure in Incommensurate-Phase Crystals

Experimental and theoretical studies of the optical birefringence increment in the transition and metastable states of the incommensurate phase of Rb₂ZnBr₄, N(CH₃)4]₂MeCl₄ (Me = Zn, Cu, Fe) crystals have been made. It has been established that in the modulated structure field a defect density wave is formed. It has been shown that when the period of the defect density wave coincides with the period of the modulation wave, the region of existence of the metastable state expands; when the periods of these waves do not coincide, their superposition occurs, with the formation of a wave with a difference value of the modulation vector. The presence of defect density waves in the incommensurate phase leads to a temperature hysteresis and kinetics of the physical quantities in the vicinity of T_c. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 632–639, September–October, 2005.