Freestanding Ferroelectric Thin Film with Robust Ferroelectricity Via Inserted Dielectric Layers

Abstract

Freestanding ferroelectric thin films offer a versatile platform for design novel physic phenomenon and flexible functionalities. However, the freestanding configuration also significantly affect the polarization stability in ferroelectric thin films, resulting unstable ferroelectric polarization switching. In this study, a strategy was proposed to stabilize the polarization of freestanding ferroelectric thin films by constructing multilayer with varying numbers and thicknesses of inserted dielectric layers. When BTO-STO multilayers structured with 11 inserted STO layers at a thickness of 2.1 nm, a robust ferroelectricity was achieved, reaching approximately 21.63 μC/cm2 (Ps), which is increased by about 95.92 % than that of BTO thin film. Furthermore, optimized BTO-STO multilayers can sustain a robust polarization of around 19.82 μC/cm2 (Ps) in a freestanding configuration, which is attributed to the multilayer geometry can preserve high-strain state and weaken the relaxation of BTO layers. This approach offers an effective strategy for construct freestanding thin films with robust ferroelectricity and provides a material basis for design freestanding flexible ferroelectric devices.

Keywords: Ferroelectric, Freestanding thin films, BaTiO3, SrTiO3, Ferroelectricity