Field-driven electro-optic dynamics of polar nanoregions in nanodisordered KTa1−<i>x</i>Nb<i>x</i>O3 crystal

Abstract

Polar nano-regions (PNRs) are considered to be responsible for giant electro-optic (EO) and piezoelectric effects, but the PNR response mechanism remains unclear. For our further understanding of the PNR field-driven dynamics, we investigate quadratic and linear EO effects in nanodisordered KTa1−xNbxO3 at (Tc + 2 °C) under various ac and (ac + dc) electric fields. The large EO effects exhibit a strong electric field dependence. Our results show that non-ergodic PNRs have vibrational and reorientational field-driven dynamics that jointly contribute to the dynamic EO characteristics. Further, macroscopic symmetry breaking under a bias electric field induces the intrinsic linear EO effect. This understanding of the dynamic EO characteristics and field-driven dynamics of PNRs will be valuable for photonic device development and provide a basis for exploring the origin of giant EO and piezoelectric effects in disordered ferroelectrics and relaxors.