Switching effects of spontaneously formed superlattices in relaxor ferroelectrics

Relaxor ferroelectrics have found significant applications in various functional devices in photonics and electronics because of their extraordinary optical and dielectric properties which are directly associated with the polarization relaxation dynamics. However, the related mechanism remains not clearly understood nowadays especially for the polar domain reversal in nanostructured relaxor ferroelectrics. This paper reports an observation of intriguing spontaneous superlattices formation of self-ordered nanostructures in a ferroelectric perovskite of KTN:Cu by cooling the crystal below the temperature of its dielectric maximum. More importantly, the strong diffraction induced by the spontaneously formed superlattices can be switched with an AC electric field after a pre-polarization using a DC electric field. The experimental results indicate the switching effect originates from an asymmetric reversal process of the polarization in nanoscale domains. The study not only facilitates further understanding the physics of the ferroelectric relaxation process, but also have potential applications in optical switching, imaging and display.