Linear and Nonlinear Elastic Properties of CuInP2S6 Layered Crystals Under Polarization Reversal

In current contribution we present results of elastic and piezoelectric investigations of CuInP2S6 crystals with applied DC electric field along polar c-axis. The behaviour of piezoelectric effect have been controlled by measuring of the signal appearing on CuInP2S6 plate, which works as receiving ultrasonic transducer. It was shown that piezoelectric sensitivity in the polar phase increases with DC field, then saturates, and after reversion of voltage the piezoelectric signal decreases, at field near coercive changes sign, and saturates again at high voltage of opposite polarity. Consequently, the hysterezis loops of piezoelectric signal amplitude were observed. In the vicinity of coercive field peaks of longitudinal ultrasonic attenuation, elastic nonlinearity and ultrasonic velocity minima were observed. The layered CuInP2S6 crystals exhibit extremely large elastic nonlinearity.