The novel mechanism for field-enhanced effect of the dielectric response in relaxor KTN crystal

Recent experiment reveals that the dielectric response to the bias electric field has obvious dependence on the frequency, which is mainly manifested in strong field-enhanced effect and weak field-enhanced effect, and reveals the novel mechanism behind this behavior. We find that the strong field-enhanced effect is caused by electromechanical coupling resonance originating from field-induced rearrangement. Considering inherent multiscale inhomogeneity, multiscale polar nanoregions distribute in the KTN crystal, and we find that the dielectric permittivity can be increased by enhanced vibration caused by the resonance between the multiscale PNRs and electric field, resulting in weak field-enhance effect. In addition, the multiscale inhomogeneity can also cause local nonmonotonic behavior of dielectric response to the electric field. Our finding provides a better understanding for the field-driven dynamics of the multiscale PNRs and paves the way to develop promising electro-optic devices, deflectors and tunable device.