Mechanical Switching of Ferroelectric Domains in 33‐200 nm‐Thick Sol‐Gel‐Grown PbZr_0.2Ti_0.8O₃ Films Assisted by Nanocavities

Abstract

The mechanical switching of ferroelectric domains is achieved in PbZr0.2Ti0.8O3 thin films obtained by the sol-gel method for thicknesses up to 200 nm. The dielectric polarization can be switched when a force higher than a given threshold value in the order of some µNewtons is applied with the tip of an atomic force microscope. This threshold is determined as a function of the thickness of the films, and local hysteresis loops are recorded under mechanical stress. The possibility of switching the polarisation in such unusually thick films is related to the existence in their volume of physical nanoscale defects, which might play the role of pinning centers for the domains.

An electric-field-driven ferroelectric nanodomain structure and its multilevel data storage application

“…These typical polydomain structures are consistent with the early ones observed in the (001)-/(101)- and (111)-oriented PbZr 0.2 Ti 0.8 O 3 /SrRuO 3 heterostructures, with the latter exhibiting complex, nanotwinned ferroelectric domain structures with high densities of 90° domain walls. 23–26…”

“…These typical polydomain structures are consistent with the early ones observed in the (001)-/(101)-and (111)-oriented PbZr 0.2 Ti 0.8 O 3 /SrRuO 3 heterostructures, with the latter exhibiting complex, nanotwinned ferroelectric domain structures with high densities of 901 domain walls. [23][24][25][26] The local PFM amplitude and phase hysteresis loops of the three oriented heterostructures are shown in Fig. 2, in which the reversal electric fields of the three oriented heterostructures differ a lot, indicating their different switching processes.…”

“…Although the dynamics process of the nanodomain switching is hard to observe via PFM, the static nanodomain structures are helpful to analyze the growth of nanodomain dynamics and the motion of domain walls. [23][24][25][26][27] It should be noted that we mainly focus on the out-ofplane nanodomain structures. Considering that the reversal voltages of the three oriented heterostructures are all about AE6 V, the strength of the tip electric pulse is controlled in the range of AE6 V B AE8 V. Before the positive or negative voltage pulses are applied to the PbZr 0.2 Ti 0.8 O 3 /SrRuO 3 heterostructures, the whole region of 5 mm  5 mm is poled by negative or positive voltage sweeps.…”

“…Among the various ferroelectric materials, PbZr 0.2 Ti 0.8 O 3 epitaxial films have rich nanodomain structures that can be tuned by varying epitaxial strain, film thickness, and electrical boundary conditions, making them an ideal candidate for ferroelectric material-based artificial synapses. [20][21][22][23][24][25][26] Researchers have found significant differences between (001)-/(101)-and (111)-oriented PbZr 0.2 Ti 0.8 O 3 films, in which (111)-oriented films had complex, nanotwinned ferroelectric domain structures with high-density 901 domain walls, broader ferroelectric switching characteristics, and lower threshold fields for nonlinearity. [20][21][22][23][24][25][26] Although simulations and studies have revealed that switching mechanisms depend on domain wall energy, elastic strain, and domain size in (001)-/(101)-and (111)-oriented PbZr 0.2 Ti 0.8 O 3 films, [20][21][22][23][24][25][26] the evolution of domain structures at the nanoscale has not been revealed in detail.…”

“…[20][21][22][23][24][25][26] Researchers have found significant differences between (001)-/(101)-and (111)-oriented PbZr 0.2 Ti 0.8 O 3 films, in which (111)-oriented films had complex, nanotwinned ferroelectric domain structures with high-density 901 domain walls, broader ferroelectric switching characteristics, and lower threshold fields for nonlinearity. [20][21][22][23][24][25][26] Although simulations and studies have revealed that switching mechanisms depend on domain wall energy, elastic strain, and domain size in (001)-/(101)-and (111)-oriented PbZr 0.2 Ti 0.8 O 3 films, [20][21][22][23][24][25][26] the evolution of domain structures at the nanoscale has not been revealed in detail. Understanding their evolution can help researchers precisely control nanoscale domain structures in ferroelectric materials, leading to interesting multi-state devices and ferroelectric material-based artificial synapses.…”