Landau Ginzburg Devonshire Research Articles

Accurate compact nonlinear dynamical model for a volatile ferroelectric ZrO2 capacitor

We have measured the dynamical response of ZrO2 capacitors to applied triangular voltage waveforms with varying frequencies and amplitudes to determine the voltage and charge on the devices as a function of time. We have fit our experimental results to a Landau–Khalatnikov dynamical equation with a sixth order Landau–Ginzburg–Devonshire polynomial to represent the static charge-voltage behavior, and obtained coefficients of determination R2 > 0.99 for the fits. Analysis of the resulting quantitative model reveals an extremely small range of negative differential capacitance <16 mV. The hysteresis loops in the dynamical charge-voltage curves are found to result primarily from energy loss during the ferroelectric transitions, as represented by a frequency-dependent series resistance in the model.

Influence of Stress on the Chiral Polarization and Elastrocaloric Effect in BaTiO3 with 180° Domain Structure

The polarization and elastrocaloric effect of chiral barium titanate (BaTiO3) with an Ising–Bloch-type domain wall under stress was investigated using the Landau–Ginzburg–Devonshire (LGD) theory. It has been shown that tensile stresses increase the magnitude of the Ising polarization component in barium titanate, together with a decrease in the domain wall width. Compressive stresses cause a reduction in the Ising polarization component and an increase in the domain width. Under compressive stress, barium titanate exhibits a negative elastrocaloric effect and temperature changes with increasing stress, while BaTiO3 exhibits a positive elastrocaloric effect under tensile stress. Bloch polarization shows angle-dependent polarization under external force, but the temperature change from the elastrocaloric effect is smaller than that of Ising polarization under stress. This work contributes to the understanding of polarization evolution under tension in ferroelectrics with chiral structure.

Influence of chemical strains on the electrocaloric response, polarization morphology, tetragonality, and negative-capacitance effect of ferroelectric core-shell nanorods and nanowires

Using Landau-Ginzburg-Devonshire (LGD) approach, we proposed the analytical description of the influence of chemical strains on spontaneous polarization and the electrocaloric response in ferroelectric core-shell nanorods. We postulate that the nanorod core presents a defect-free single-crystalline ferroelectric material, and elastic defects are accumulated in the ultrathin shell, where they can induce tensile or compressive chemical strains. Finite-element modeling (FEM) based on the LGD approach reveals transitions of domain-structure morphology induced by chemical strains in the BaTiO3 nanorods. Namely, tensile chemical strains induce and support the single-domain state in the central part of the nanorod, while the curled domain structures appear near the unscreened or partially screened ends of the rod. The vortexlike domains propagate toward the central part of the rod and fill it entirely, when the rod is covered by a shell with compressive chemical strains above some critical value. The critical value depends on the nanorod sizes, aspect ratio, and screening conditions at its ends. Both analytical theory and FEM predict that the tensile chemical strains in the shell increase the nanorod polarization, lattice tetragonality, and electrocaloric response well above the values corresponding to the bulk material. The physical reason for the increase is strong electrostriction coupling between the mismatch-type elastic strains induced in the core by chemical strains in the shell. Comparison with earlier XRD data confirmed an increase of the tetragonality ratio in tensile BaTiO3 nanorods compared to the bulk material. Obtained analytical expressions, which are suitable for the description of strain-induced changes in a wide range of multiaxial ferroelectric core-shell nanorods and nanowires, can be useful for strain engineering of advanced ferroelectric nanomaterials for energy storage, harvesting, electrocaloric applications, and negative capacitance elements. Published by the American Physical Society 2024

Ferroelectric Thin Films and Composites Based on Polyvinylidene Fluoride and Graphene Layers: Molecular Dynamics Study

This work is devoted to the study of nanosized polymer polyvinylidene fluoride (PVDF) thin ferroelectric films (two-dimensional ferroelectrics) and their composites with graphene layers, using molecular dynamics methods to (1) study and calculate the polarization switching time depending on the electric field and film thickness, (2) study and calculate the polarization switching time depending on changes of the PVDF in PVDF-TrFE film, and (3) study the polarization switching time in PVDF under the influence of graphene layers. All calculations at each MD run step were carried out using the semi-empirical quantum method PM3. A comparison and analysis of the results of these calculations and the kinetics of polarization switching within the framework of the Landau–Ginzburg–Devonshire theory for homogeneous switching in ferroelectric polymer films is carried out. The study of the composite heterostructures of the “graphene-PVDF” type, and calculations of their polarization switching times, are presented. It is shown that replacing PVDF with PVDF-TrFE significantly changes the polarization switching times in these thin polymer films, and that introducing various graphene layers into the PVDF layered structure leads to both an increase and a decrease in the polarization switching time. It is shown that everything here depends on the position and displacement of the coercive field depending on the damping parameters of the system. These phenomena are very important for various ferroelectric coatings.

Bending-induced isostructural transitions in ultrathin layers of van der Waals ferrielectrics

Using Landau-Ginzburg-Devonshire (LGD) phenomenological approach we analyze the bending-induced re-distribution of electric polarization and field, elastic stresses and strains inside ultrathin layers of van der Waals ferrielectrics. We consider a CuInP2S6 (CIPS) thin layer with fixed edges and suspended central part, the bending of which is induced by external forces. The unique aspect of CIPS is the existence of two ferrielectric states, FI1 and FI2, corresponding to big and small polarization values, which arise due to the specific four-well potential of the eighth-order LGD functional. When the CIPS layer is flat, the single-domain FI1 state is stable in the central part of the layer, and the FI2 states are stable near the fixed edges. With an increase of the layer bending below the critical value, the sizes of the FI2 states near the fixed edges decreases, and the size of the FI1 region increases. When the bending exceeds the critical value, the edge FI2 states disappear being substituted by the FI1 state, but they appear abruptly near the inflection regions and expand as the bending increases. The bending-induced isostructural FI1-FI2 transition is specific for the bended van der Waals ferrielectrics described by the eighth (or higher) order LGD functional with consideration of linear and nonlinear electrostriction couplings. The isostructural transition, which is revealed in the vicinity of room temperature, can significantly reduce the coercive voltage of ferroelectric polarization reversal in CIPS nanoflakes, allowing for the curvature-engineering control of various flexible nanodevices.

Phase field study on the flexoelectric response of dielectric–ferroelectric multilayers

We report a theoretical modeling of the flexoelectric response of dielectric–ferroelectric (DE–FE) multilayers based on phase field simulations in the framework of the Landau–Ginzburg–Devonshire (LGD) theory. The correlation between negative capacitance and flexoelectric response is revealed, and the single-domain and multi-domain models are compared. It shows that the dielectric layers drive the ferroelectric layer into a negative capacitance regime, and the flexoelectric response of the multilayer is maximal when the negative capacitance of the ferroelectric layer has a minimal absolute value. Moreover, the flexoelectric response peak will be shifted to a lower temperature by increasing the thickness of dielectric layer, indicating a possibility of achieving a stronger flexoelectric response at room temperature compared with that of pure ferroelectric. However, while the single-domain model shows that the flexoelectric response peak is simply shifted to a lower temperature with near constant peak value and width, the multi-domain model reveals a significant suppressing of the flexoelectric peak by the dielectric layer. This is attributed to the formation of the vortex domain state, which eases the depolarization effect and leads to large absolute value of negative capacitance of the ferroelectric layer. Our work provides new insights into flexoelectricity in ferroelectric heterostructures.

Electrocaloric Effect in Multilayer Ferroelectric Structures

Introduction. Ferroelectric films are widely used for radiotechnical, microwave microelectronic, sensoric, and energy conversion purposes. Such a diverse application range demands film materials with specific electrophysical properties. For instance, while energy storage applications require materials with a high dielectric constant, energy conversion devices largely use those with a low dielectric constant. The necessary physical properties can be achieved using multicomponent ferroelectric structures, such as solid solutions, composites, and multilayer film structures. Mechanical stresses between the substrate and ferroelectric layers play an extremely important role in dielectric properties of multilayer structures.Aim. Development of a mathematical model quantifying the ferroelectric polarization, static dielectric constant, as well as pyroelectric and electrocaloric properties of multilayered ferroelectric film structures.Materials and methods. The presented model is based on the Landau–Ginzburg–Devonshire model (LGD) considering elasticity equations and using electric induction as the order parameter.Results. The developed mathematical model based on LGD provides for a quantifiable description of dielectric, pyroelectric, and electrocaloric properties of layered ferroelectric structures. This model displays the effect of the thickness ratio of polycrystalline layers and grain size distribution on the dielectric properties of films.Conclusion. The developed quantitative model demonstrates the dependence of the thickness, grain size, and stacking order of ferroelectric layers on the dielectric constant and pyroelectric coefficient of multilayered polycrystalline film structures. The presented model can be applied when optimizing the parameters of multilayer structures with respect to their application area.

Numerical modeling of anisotropic ferroelectric materials with hybridizable discontinuous Galerkin methods

We investigate a gradient flow structure of the Ginzburg–Landau–Devonshire (GLD) model for anisotropic ferroelectric materials by reconstructing its energy form. We show that the modified energy form admits at least one minimizer. Under some regularity assumptions for the electric charge distribution and the initial polarization field, we prove that the gradient flow structure has a unique solution. To simulate the GLD model numerically, we propose an energy‐stable semi‐implicit time‐stepping scheme and a hybridizable discontinuous Galerkin method for space discretization. Numerical tests are provided to verify the stability and convergence of the proposed numerical scheme as well as some properties of ferroelectric materials.

Polarization-controlled volatile ferroelectric and capacitive switching in Sn2P2S6

Smart electronic circuits that support neuromorphic computing on the hardware level necessitate materials with memristive, memcapacitive, and neuromorphic- like functional properties; in short, the electronic response must depend on the voltage history, thus enabling learning algorithms. Here we demonstrate volatile ferroelectric switching of Sn2P2S6 at room temperature and see that initial polarization orientation strongly determines the properties of polarization switching. In particular, polarization switching hysteresis is strongly imprinted by the original polarization state, shifting the regions of non-linearity toward zero-bias. As a corollary, polarization switching also enables effective capacitive switching, approaching the sought-after regime of memcapacitance. Landau–Ginzburg–Devonshire simulations demonstrate that one mechanism by which polarization can control the shape of the hysteresis loop is the existence of charged domain walls (DWs) decorating the periphery of the repolarization nucleus. These walls oppose the growth of the switched domain and favor back-switching, thus creating a scenario of controlled volatile ferroelectric switching. Although the measurements were carried out with single crystals, prospectively volatile polarization switching can be tuned by tailoring sample thickness, DW mobility and electric fields, paving way to non-linear dielectric properties for smart electronic circuits.

Size-Dependent Switching in Thin Ferroelectric Films: Mathematical Aspects and Finite Element Simulation

The paper is devoted to the theoretical analysis and numerical implementation of a mathematical model of a nonlinear reaction–diffusion system on the COMSOL Multiphysics platform. The applied problem of the computer simulation of polarization switching in thin ferroelectric films is considered. The model is based on the Landau–Ginzburg–Devonshire–Khalatnikov thermodynamic approach and formalized as an initial-boundary value problem for a semilinear parabolic partial differential equation. The theoretical foundations of the model were explained. The user interface design application was developed with COMSOL Multiphysics. A series of computational experiments was performed to study the ferroelectric hysteresis and temperature dependences of polarization on the example of a ferroelectric barium titanate film.

Dynamics and Modeling of Multidomains in Ferroelectric Tunnel Junction—Part-II: Electrostatics and Transport

We have derived the 2-D analytical multidomain electrostatics model of the ferroelectric tunnel junction (FTJ) in part-I of this work. Here, we have used the 2-D potential functions from part-I to determine the depolarizing energy density of the ferroelectric layer. The coupled solution of the Landau Ginzburg–Devonshire (LGD) equation with Poisson’s equation is obtained to capture the domain texture in the ferroelectric layer. The nucleation and movement of the domain wall are incorporated into the model by minimizing net ferroelectric energy (depolarization energy density + free energy density + gradient energy density). Due to the mathematical complexity, spontaneous polarization <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$({P}_{s})$ </tex-math></inline-formula> and coercive electric field <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$({E}_{c})$ </tex-math></inline-formula> are assumed to be fixed, and the net system energy is minimized only by domain wall nucleation and movement in the ferroelectric layer. The analysis of this article is twofold; first, we study the impact of domain dynamics on electrostatics in an FTJ. Subsequently, the obtained electrostatics is used to study the variations in tunneling current, and ON/OFF ratio [tunnel electroresistance (TER)] originated from multidomain dynamics. We show that ON/OFF tunneling current density and TER varies locally in the ferroelectric region, and approximately one-decade local variations in current density are observed. The optimization techniques to achieve a uniform and maximum TER are also discussed. Furthermore, the impact of the bottom insulator layer on ferroelectric’s gradient energy is also studied.

Double S‐Shaped Polarization – Voltage Curve and Negative Capacitance from Al2O3‐Hf0.5Zr0.5O2‐Al2O3Triple‐Layer Structure

AbstractThe negative capacitance (NC) effect, recently discovered in a fluorite‐based ferroelectric thin film, has attracted great attention as a rescue to overcome the scaling limitations of the conventional memory and logic devices of highly integrated circuits. The NC effect manifesting an S‐shaped polarization–voltage (P–V) curve is initially interpreted by a 1‐dimensional Landau Ginzburg Devonshire (LGD) model. However, a series of recent studies have found that this effect can also be explained by the inhomogeneous stray field energy (ISE) model. In this study, by extending the ISE model in the ferroelectric (FE)‐dielectric (DE) layered structure, an analytical model that considers the influence of the interfacial screening charge distribution is presented. This model showed that the NC effect in the FE‐DE heterostructure can be manifested in various forms other than a single S‐shapedP–Vcurve. In particular, a double S‐shapedP–Vcurve is expected from the fully compensated anti‐parallel domain structure, confirmed experimentally in the actual Al2O3/(Hf0.5Zr0.5)O2/Al2O3triple‐layer structure. Furthermore, to reveal the origin of the double S‐shapedP–Vcurve, a multidomain LGD model is presented. It is confirmed that this phenomenon is attributed to the evolution of inhomogeneous stray field energy.

Structures and velocities of noisy ferroelectric domain walls

Ferroelectric domain wall motion is fundamental to the switching properties of ferroelectric devices and is influenced by a wide range of factors including spatial disorder within the material and thermal noise. We build a Landau-Ginzburg-Devonshire (LGD) model of ${180}^{\ensuremath{\circ}}$ ferroelectric domain wall motion that explicitly takes into account the presence of both spatial disorder and thermal noise. We demonstrate both creep flow and linear flow regimes of the domain wall dynamics by solving the LGD equations in a Galilean frame moving with the wall velocity $v$. Thermal noise plays a key role in the wall depinning process at small fields $E$. We study the scaling of the velocity $v$ with the applied DC electric field $E$ and show that noise and spatial disorder strongly affect domain wall velocities. We also show that domain walls develop a local, metastable paraelectric region and widen significantly in the presence of thermal noise in materials with ``multiwell'' potentials, representative of ferroelectrics at temperatures $T$ just below a first-order phase transition (Curie) temperature ${T}_{c}$. These calculations point to the potential of noise and disorder to become control factors for the switching properties of ferroelectric materials, for example for advancement of microelectronic applications.

Time-fractional Landau–Khalatnikov model applied to numerical simulation of polarization switching in ferroelectrics

Ferroelectrics are complex structured media that exhibit fractal properties and memory effects in terms of a number of dynamic characteristics. The most relevant applications of ferroelectrics in science and technology are associated with the primary mechanisms of polarization switching and domain structure dynamics induced by external exposure. In this study, we propose a time-fractional modification of the Landau–Ginzburg–Devonshire–Khalatnikov model to describe the dynamics of ferroelectric polarization switching. To solve the time-fractional cubic-quintic partial differential equation numerically, a computational scheme is derived. The technique combines an iterative procedure and an implicit finite-difference scheme based on an approximation of the Caputo derivative. A series of computational experiments are presented to visualize polarization switching characteristics on the example of thin films of barium titanate. A variation of the order of fractional derivative as a numerical characteristic of the memory effect allows one to “adjust” suitable regimes of simulated dynamical system. The obtained findings indicate that the generalized time-fractional model can provide better reproduction of experimental data in comparison with the classical analogue.

Electric field control of labyrinth domain structures in core-shell ferroelectric nanoparticles

In the framework of the Landau-Ginzburg-Devonshire (LGD) approach, we studied the possibility of controlling the polarity and morphology of equilibrium domain structures by a homogeneous external electric field in a nanosized ferroelectric core covered with an ultrathin shell of screening charge. Under certain screening lengths and core sizes, the minimum of the LGD energy, which consists of Landau-Devonshire energy, Ginzburg polarization gradient energy, and electrostatic terms, leads to the spontaneous appearance of stable labyrinth domain structures in the core. The labyrinths evolve from an initial polarization distribution consisting of arbitrarily small randomly oriented nanodomains. The equilibrium labyrinth structure is weakly influenced by details of the initial polarization distribution, such that one can obtain a quasicontinuum of nearly degenerate labyrinth structures, whose number is limited only by the mesh discretization density. Applying a homogeneous electric field to a nanoparticle with labyrinth domains, and subsequently removing it, allows inducing changes to the labyrinth structure, as the maze polarity is controlled by a field projection on the particle polar axis. Under specific conditions of the screening charge relaxation, the quasistatic dielectric susceptibility of the labyrinth structure can be negative, potentially leading to a negative capacitance effect. Considering the general validity of the LGD approach, we expect that an electric field control of labyrinth domains is possible in many spatially confined nanosized ferroics, which can be potentially interesting for advanced cryptography and modern nanoelectronics.

Multi-objective optimization of pyroelectric thermal–electrical cycles

Pyroelectric thermal–electrical cycles enable a class of solid-state heat engines that convert waste heat to electrical energy. This article numerically investigates thermal-to-electrical energy conversion in a PbZr0.52Ti0.48O3 (PZT) pyroelectric layer near room temperature and optimizes operating parameters to maximize the electrical energy output. A general thermodynamic cycle is modeled after the prototypical pyroelectric Ericsson cycle—implemented based on the Ginzburg–Landau–Devonshire theory—with variable operating temperature range, and heating/cooling and charging/discharging time intervals. We used a Pareto optimization approach to simultaneously maximize electrical energy density and power density for different PZT sample and cycle parameters. The evaluated Pareto optimal fronts showcase the possibility of achieving multiple optimal solutions and highlight the trade-off between output energy density and power density in pyroelectric energy conversion. Specifically, we demonstrate that a 4× enhancement in power density is achievable with a less than 10% reduction in energy density for the same sample and operating conditions primarily by optimizing heat transfer. The multi-objective optimization approach and results presented in this study could provide a framework to facilitate the design and operation of pyroelectric cycles for waste heat energy harvesting systems.

Improved energy storage and electrocaloric properties of lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramic

Lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramic powders were synthesized using the sol–gel method. The ceramics thickness was reduced to achieve high-energy storage and large electrocaloric effect in bulk ceramics. Dielectric, ferroelectric, energy storage, and electrocaloric properties were investigated for BCZT ceramic with 400 µm. Here, pure crystalline structure and homogenous microstructure were identified by XRD analysis and SEM measurements, respectively. The dielectric measurements revealed a maximum dielectric constant associated with ferroelectric–paraelectric phase transition. The maximum of $$\varepsilon^{\prime}_{{\text{r}}}$$ was 17841, around 352 K. Furthermore, the BCZT ceramic exhibited improved energy storage and electrocaloric properties. A high recoverable energy density Wrec of 0.24 J/cm3 and a total energy density Wtotal of 0.27 J/cm3 with an efficiency coefficient of ~ 88% at 423 K under an electric field of 55 kV/cm were obtained. Besides, The maximum value of ΔT = 2.32 K, the electrocaloric responsivity ζ = 0.42 K mm/kV, the refrigeration capacity RC = 4.59 J/kg and the coefficient of performance COP = 12.38 were achieved around 384 K under 55 kV/cm. The total energy density Wtotal and the temperature change ΔT were also calculated by exploiting the Landau–Ginzburg–Devonshire (LGD) theory. The theoretical results matched the experimental findings. These results suggest that the synthesized BCZT ceramic with reduced thickness could be a promising candidate for energy storage and electrocaloric applications.

A phenomenological study on temperature-concentration-electric field phase diagram of relaxor ferroelectrics PMN-PT single crystals

The theoretical temperature-concentration-electric field (T-x-E) phase diagram of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) is investigated under the electric fields applied along the [001], [011] and [111] directions in the pseudo-cubic coordinate. Using the structurally stable tenth-order Landau–Ginzburg–Devonshire potential model, different two-dimensional sections of T-x-E phase diagram such as T-x (E[001] = E[101] = 0.1, 1kV/㎝) and E-T (x = 0.26, 0.28, 0.3, 0.32, 0.34, 0.36 and 0.38) phase diagrams, and T-x-E[001] one are constructed for PMN-PT single crystals. Also, based on the phenomenological results for T-x-E phase diagram, the features of symmetry changes from high symmetry phase, cubic one, to low symmetry phases, rhombohedral, tetragonal, orthorhombic, monoclinic and triclinic ones, possible during the phase transitions occurring at different temperatures, concentrations and electric fields in PMN-PT single crystals are predicted. The anomalies in dielectric and piezoelectric coefficients accompanied with the symmetry changes are studied. The topological features of T-x-E phase diagram of PMN-PT single crystals are qualitatively in good agreement with those of different piezo/ferroelectrics (BaTiO3, KNbO3, (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT)) in which the symmetry of order parameter is characterized by the image-group ImΓ4− = m3m of the irreducible representation Γ4− of the space group Pm3‾m as in PMN-PT single crystals.

Negative Capacitance in HfO2 Gate Stack Structures With and Without Metal Interlayer

In this work, we experimentally explore and compare FET gate stacks with and without an inner metal plane between a linear dielectric (SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) and a ferroelectric layer (Si-doped HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) operating in the negative capacitance (NC) regime. The use of nanosecond-range pulses enables us to observe hysteresis-free NC and reconstruct the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> -shaped polarization-voltage curves. The devices with the inner metal plate show a higher equivalent NC value, which offers the potential for a higher differential amplification in a NC-FET. However, such a NC region is observed over a smaller range of electric field and polarization, which leads to hysteresis. Moreover, the presence of a metal layer in between the ferroelectric and the insulator favors domain formation resulting in destabilization of the NC effect. For the gate structure where the ferroelectric and the insulator are in contact, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> -shaped polarization-voltage curve shows a better agreement with Landau–Ginzburg–Devonshire formalism for the monodomain state. The uniform polarization closely mimicking the monodomain state is possible due to the polarization imprint occurring due to the structural asymmetry. By nanometer resolution polarization mapping via off-resonance piezoelectric force microscopy (PFM), we corroborate the presence of imprint, which can intrinsically stabilize one ferroelectric state. Overall, the article provides an experimental demonstration that the absence of the inner metal plane in the gate structures stabilizes the NC regime favorable for hysteresis-free NC-FET.

Improved Multibit Storage Reliability by Design of Ferroelectric Modulated Antiferroelectric Memory

In this article, we presented a new concept of ferroelectric (FE) modulated antiferroelectric (AFE) memory with independent two-step state switching and large polarization as a promising option for multibit storage in advanced technology nodes. Based on the Landau–Ginzburg–Devonshire (LGD) theory, four nonvolatile states of AFE with the built-in field can be obtained, and the step-by-step switching among four states was successfully simulated through pulse engineering; then, stable nonvolatile 2-bit storage was experimentally demonstrated in FE/AFE/FE capacitor device, and 0.97-MV/cm bipolar built-in field introduced by FE polarization switching was extracted. The FE + AFE device showed double-peak coercive electric field ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{c}$ </tex-math></inline-formula> ) distribution and large remanent polarization ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{r}$ </tex-math></inline-formula> ) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16.9 ~\mu \text{C}$ </tex-math></inline-formula> /cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with good process stability. Finally, benefitting from the independently step-by-step switching and large density of effective FE domain, the improved multibit storage reliability was verified by kinetic Monte Carlo (KMC) modeling compared to conventional multibit technology.