Thermal Memory and Phase Conjugation Experiments in Incommensurate Barium Sodium Niobate
It is known that thermal memory in incommensurate (IC) insulators arises from the “decoration” of anti-phase boundaries of the IC structure by charged defects. In materials such as BaMnF4 and Ba2NaNb5O15 that are simultaneously IC and ferroelectric, it is possible to determine the sign and diffusivity of the charged defects by four-wave mixing experiments of the type used in phase conjugate optics. Our result in Ba2NaNb5O15 is that the sign of the carriers is the same as that of the electro-optic coefficients r12, r23, r33; these coefficients are known to have the same sign, but its absolute sense is not available in the literature.
KeywordsOptical Intensity Antiphase Boundary Charged Defect Total Electric Field Statistical Mechanical Model
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