Engineered a/c domain patterns in multilayer (110) epitaxial Pb(Zr,Ti)O3 thin films: Impact on domain compliance and piezoelectric properties

Abstract

While there is extensive literature on the influence of both compressive and tensile strain on the domain patterns of (001) tetragonal ferroelectric thin films, little is known regarding domain engineering in (110) films. The primary reason is the absence of suitable substrates that allow the growth of epitaxial films with this orientation. However, recent works emphasized the importance of this orientation with the possibility for e.g. to achieve ultra-high ferroelectric domain density. This work reports the controlled growth of a/c domain patterns in highly tetragonal monocrystalline (110) oriented Pb(Zr0.05, Ti0.95)O3. It is demonstrated that while a/c patterns can easily be realized in the single layer film relaxed under compressive misfit strain, modulation of tensile misfit strain through the use of buffer layers allows for consistent control of domain periodicity, in which case the average domain period was tuned between 630 and 60 nm. The effects of domain density and defects on both switching behavior and piezoelectric properties in single and multilayered structures are also investigated, revealing an optimum composition of the buffer layer for improved domain compliance and piezoelectric properties.

Self-Organized Ferroelastic Superdomains with Enhanced Piezoresponse in (101)-Oriented Pb(Zr0.2,Ti0.8)O3 Thin Films

“…The piezoresponse hysteresis loops for both domain types are further unveiled in Figure . The P 1 / P 2 domains present a typical ferroelectric switching characteristic with a canonical loop (Figure a), consistent with the reported literature studies. ,, A sharp change at positive and negative coercive fields indicates 180° reversal of polarization as the cartoons depicted in Figure a. Interestingly, the superdomains apparently exhibit an unconventional switching behavior, which displays extra intermediate stable states during the switching cycle.…”

Crystallographic Orientation and Surface Charge-Tailored Continuous Polarization Rotation State in Epitaxially Ferroelectric Nanostructures

“…For the [101]­PTO thin films grown on STO(101) substrates, the lattice mismatch values between the stress-free thin film and substrate along the [010] and [1̅01] directions can be calculated by the following formulas and where subscripts “f” and “s” denote the PTO thin film and STO(101) substrate, respectively. Thus, the lattice mismatch values along the [010] and [1̅01] directions are determined as 0.15 and −3.15%, respectively, which indicates that the [101]­PTO thin film is strained asymmetrically in the two in-plane directions.…”

“…For the [101]PTO thin films grown on STO(101) substrates, the lattice mismatch values between the stress-free thin film and substrate along the [010] and [1̅ 01] directions can be calculated by the following formulas25 …”

Disentangling Ferroelectric Wall Dynamics and Identification of Pinning Mechanisms via Deep Learning

“…[ 19–21 ] The polar nature of the ferroelectric materials imposes the formation of bound charge at the walls with the discontinuity of polarization, resulting in characteristic instabilities of charged walls [ 22 ] and strong coupling between wall behavior and semiconducting [ 23 ] and electrochemical phenomena at surfaces and interfaces. [ 24,25 ] Notably that while ideal single crystals can form the low energy ground states with a periodic domain wall structure and minimal electrostatic and strain energy, realistic materials evolve complex nonequilibrium domain wall structures [ 26,27 ] due to complex histories, nonlocal effects due to presence of grains and surfaces, [ 28–31 ] and defects and disorder. [ 32–35 ]…”

“…[19][20][21] The polar nature of the ferroelectric materials imposes the formation of bound charge at the walls with the discontinuity of polarization, resulting in characteristic instabilities of charged walls [22] and strong coupling between wall behavior and semiconducting [23] and electrochemical phenomena at surfaces and interfaces. [24,25] Notably that while ideal single crystals can form the low energy ground states with a periodic domain wall structure and minimal electrostatic and strain energy, realistic materials evolve complex nonequilibrium domain wall structures [26,27] due to complex histories, nonlocal effects due to presence of grains and surfaces, [28][29][30][31] and defects and disorder. [32][33][34][35] Over the first half a century of physics of ferroelectrics, exploration of the domain wall dynamics was preponderantly based on theoretical models and macroscopic measurements on samples with multiple domain walls, with the additional insight from relatively low-resolution optical studies using polarized light or chemically etched/decorated samples.…”