arXiv subjects

Eugene A. Eliseev

Publications and source records attributed to Eugene A. Eliseev.

At least 19 recordsLinked to original sources

arXiv2026

Correlations of Spectroscopic and Dielectric Properties of Hafnia-Zirconia Nanoparticles

In this work we analyze correlations of X-ray photoelectron and diffraction spectra, and dielectric properties of hafnia-zirconia nanoparticles (the chemical compositions Hf0.4Zr0.6O2 and Hf0.6Zr0.4O2, and the average size of 7.5 nm) prepared by the solid-state organo-nitrate synthesis and annealed in air. The phase state of the nanoparticles, determined by the X-ray diffraction spectroscopy, is the coexistence of the nonpolar monoclinic (42 - 76 mass %) and orthorhombic (56 - 24 mass %) phases. Concentration of the oxygen vacancies was estimated from the X-ray photoelectron spectroscopy. The increase in the intensity of the dielectric permittivity maximum observed near 350 - 450 K in a PVDF matrix with embedded Hf0.4Zr0.6O2 nanoparticles can be related with an increase in oxygen vacancy concentration. Theoretical calculations, based on Landau-Ginzburg-Devonshire theory, explain the increase of the dielectric permittivity in Hf0.4Zr0.6O2 nanoparticles compared to Hf0.6Zr0.4O2 nanoparticles.

cond-mat.mtrl-sci↗

arXiv2026

Stress-Induced Ferroelectricity in Hafnium Oxide Core-Shell Nanoparticles

In contrast to hafnia (HfO2) thin films, where the appearance of switchable ferroelectric polarization can be induced by strain or defect engineering, reliable methods for controlling ferroelectricity are absent in HfO2 nanoparticles. Direct experimental observations of ferroelectric hysteresis and ferroelectric domains in these nanoparticles are also absent. To the best of our knowledge, stress-induced ferroelectric states in the HfO2 nanoparticles have not been explored. In this work, we study the influence of chemical stress on phase diagrams, dielectric and polar properties of spherical HfO2 core-shell nanoparticles using a Landau-Ginzburg-Devonshire free energy functional that includes trilinear and biquadratic couplings involving polar, antipolar, and nonpolar order parameters. The ferroelectric phase exhibits reentrant behavior as a function of nanoparticle size, such that the spontaneous polarization exists only within a limited range of core radii R_c, namely R_cr^min<R_c<R_cr^max. The minimal critical radius R_cr^min is primarily determined by the size dependence of the depolarization field and correlation effects; the maximal critical radius R_cr^max is primarily determined by the size dependence of chemical stresses induced by the elastic defects in the shell. Thus, this work identifies a stress-driven mechanism for reentrant ferroelectricity stabilization in nanoscale HfO2 systems, arising from the competition between depolarization field-induced suppression of ferroelectricity and its stabilization by shell-induced chemical stress. We revealed that relatively large compressive chemical strains are necessary to induce the ferroelectric phase in the HfO2 nanoparticles. Successful chemical strain engineering opens the way for significant enhancement of nanoscale HfO2 polar properties for applications in advanced memory cells and logic devices.

cond-mat.mtrl-sci↗

arXiv2026

A colossal dielectric response of Bi1-xSmxFeO3 nanopowders

The dielectric permittivity of the pressed powder samples of Bi1-xSmxFeO3, with Sm content "x" varying in the range 0 - 0.2, has been investigated in the temperature range from 20 to 400 C and the frequency range from 100 Hz to 100 kHz. We have shown that the Sm content impacts significantly the real and imaginary parts of effective dielectric permittivity, which have expanded diffuse maxima with a colossal magnitude up to 105 (for the real part) and up to 108 (for the imaginary one) at temperatures 300 - 400 K. Analysis of experimental data carried has shown that both the real and imaginary parts of effective dielectric permittivity may be comprehensively explained by considering a complex interplay of a diffuse ferroelectric-paraelectric phase transition and the Maxwell-Wagner-Sillars effects, which emerge from the formation of spatial charges at interfaces between nanograins and at the ferroelectric nanoparticle-air interface. Processing of experimental data for the real and imaginary parts of the effective dielectric permittivity within effective medium approach allows us to separate and analyze the colossal dielectric response of the nanoparticles itself. The main trends followed from experiments are supported by the theoretically simulated dependences, which reveal correlations between the temperature behavior of dielectric properties and phase state of the Bi1-xSmxFeO3 nanoparticles.

cond-mat.mtrl-sci↗

arXiv2026

Bilinear Flexo-Antiferrodistortive Coupling in Ferroelastics: Polar Twins, Antiphase Boundaries and Fingerprints of Alterelectricity

Using the Landau-Ginsburg-Devonshire approach we show that the linear gradient-type coupling between the electric polarization vector and antiferrodistortive long-range order parameter pseudovector, that has the form of Lifshitz invariant and named "bilinear flexo-antiferrodistortive coupling", can emerge in all antiferrodistortive ferroelastics, since it is symmetry-allowed. Using the four sublattices model we reveal that the bilinear flexo-antiferrodistortive coupling can induce the sublattice-sensitive polarization at the twin walls and antiphase boundaries in antiferrodistortive ferroelastics without any ferroelectric or antiferroelectric ordering. Since the induced polarization is perpendicular to the antiferrodistortive long-range order parameter and counter-directed in neighboring sublattices with checkerboard-type direction of antiferrodistortive long-range order parameter, such structure of polarization may correspond to the alterelectric-type quadrupolar electric order. However, physical manifestations of the bilinear flexo-antiferrodistortive coupling are invisible in most nanostructured antiferrodistortive ferroelectrics and antiferroelectrics due to the domination of piezoelectric and/or omnipresent linear flexoelectric couplings.

cond-mat.mtrl-sci↗

arXiv2026

Flexo-Strain Engineering of Phonons and Ferrons in Thin Films of Van der Waals Ferrielectrics

The influence of the flexoelectric coupling on the fluctuations of electric polarization and elastic strains can lead to the principal changes of the dispersion law of soft optical and acoustic phonons and ferrons in a bulk van der Waals ferrielectric. Since the size, gradient and strain effects determine phase diagrams and polarization behavior in thin films, it is reasonable to assume that the flexocoupling and mismatch strains should have a strong influence on the dispersion of phonons and ferrons in thin ferroelectric films. Using the Landau-Ginzburg-Devonshire approach, in this work we reveal that the dispersion of soft optical and acoustic phonons and ferrons is strongly dependent on the sign and magnitude of elastic strains, which originate from the lattice constants mismatch in thin strained films of van der Waals ferrielectric CuInP2S6. In particular, the frequency of acoustic phonons and ferrons approaches zero at nonzero wavevectors k>k_cr, where the critical value of the wavevector k_cr is determined by the mismatch strain, flexoelectric coupling strength and temperature. Zeroing of the acoustic phonon frequency, that appears with increase of tensile strains, indicates a possible emergence of a spatially modulated incommensurate polar phase induced by the flexo-strain effects. Analytical results, derived in this work, open the way for flexo-strain engineering of soft phonon and ferron dispersion in thin films of van der Waals ferrielectrics.

cond-mat.mtrl-sci↗

arXiv2026

Composition-Driven Phase Evolution in Sm-Doped BiFeO3 via Latent-Field Reconstruction of Atomically Resolved STEM Data

Functionalities of ferroelectric materials are governed by the spatial organization and coupling of polarization, strain, lattice rotation, and structural order accessible via atomically resolved scanning transmission electron microscopy (STEM) images. Quantitative interpretation of atomic-resolution STEM data has conventionally relied on locating atomic columns and converting their fitted coordinates into local structural descriptors. Here, we develop a field-based approach in which atomic-resolution images are represented by spatially varying latent Bragg fields, whose amplitudes and phases provide continuous maps of crystalline order, lattice displacement, strain, rotation, and mode-specific residual structure. The observed atomically resolved images are decoded from the latent fields. We apply this framework to image series of Sm-substituted BiFeO3 spanning 0-20% Sm and crossing the composition-driven boundary between the R3c ferroelectric phase and the orthorhombic, nonpolar Pnma phase. Conventional atom-resolved parameterization is used as an independent validation, showing that reconstructed Bragg amplitude tracks local atomic-column intensity and that field-derived shear reproduces unit-cell angular distortions obtained from atom fitting. The combined analysis reveals a systematic evolution from extended ferroelectric domains at low Sm concentration, through the appearance and growth of localized regions with period-doubled Pnma order at intermediate compositions, to a connected Pnma-dominated state at high Sm content. The period-doubled order is accompanied by enhanced shear and lattice rotation and by progressive reorganization of the ferroelectric domain structure. These results establish latent-field reconstruction as a physically interpretable complement to atom finding and provide a unified framework for resolving composition-driven phase evolution in ferroic materials.

cond-mat.mtrl-sci↗

arXiv2026

Pyroelectric and electrocaloric properties of core-shell HfxZr1-xO2 nanoparticles: theory and experiment

Nanosized hafnia-zirconia (HfxZr1-xO2) in the form of thin films, multilayers, and nanoparticles is one of the most promising CMOS-compatible ferroelectric materials for advanced electronic memories and logic devices. Using the Landau-Ginzburg-Devonshire free energy functional with trilinear and biquadratic couplings of polar, nonpolar, and antipolar order parameters, we analyze the pyroelectric and electrocaloric properties in an ensemble of spherical core-shell HfxZr1-xO2 nanoparticles. To test the theoretical model, we experimentally measured the temperature dependence of the electric charge accumulated in pressed powders consisting of oxygen-deficient core-shell Hf0.5Zr0.5O2 nanoparticles with an average size of 7 nm. The observed temperature-dependent behavior of the accumulated charge and its derivative are in qualitative agreement with the calculated polarization and pyroelectric coefficient for the ensemble of densely packed spherical core-shell HfxZr1-xO2 nanoparticles; this suggests that the theoretical model captures the physical mechanisms responsible for the experimentally observed charge accumulation. The combined theoretical and experimental results provide a physical foundation for the future development of CMOS-compatible HfxZr1-xO2 nanoparticles for pyroelectric and electrocaloric applications.

cond-mat.mtrl-sci↗

arXiv2026

Influence of BaTiO_3 nanoparticles on the anisotropy of the dielectric properties of nematic liquid crystal 5CB

This work is devoted to the mechanisms of dielectric response and electric conductivity of suspensions consisting of the nematic liquid crystal 5CB with different concentrations (from 0 to 10 wt.%) of ferroelectric BaTiO_3 nanoparticles with an average size of 24 nm. We revealed that the incorporation of nanoparticles influences significantly the dielectric permittivity magnitude and anisotropy, as well as dielectric losses of the suspension. A pronounced temperature dependence of the anisotropic dielectric permittivity of the suspensions was found at lower temperatures corresponding to the mesophase state; but it is also present at higher temperatures corresponding to the isophase. The dependence of the mesophase-isophase transition temperature on the concentration of BaTiO_3 nanoparticles appeared nonmonotonic. With increasing temperature, both the capacitance and the electrical resistance of the pure liquid crystal increase, as well as it increases in the suspensions with small concentration of BaTiO_3 nanoparticles. Due to space charge accumulation in the shells of nanoparticles, larger concentrations of BaTiO_3 nanoparticles influence strongly the ionic transport by promoting the formation of ionic-electronic screening. This effect modifies the dielectric properties and conduction mechanisms of the suspension, leading to the nonmonotonic dependence of the mesophase - isophase transition temperature versus the nanoparticle concentration.

cond-mat.mtrl-sci↗

arXiv2026

Correlations Between the Dielectric Properties, Domain Structure Morphology and Phase State of Bi1-xSmxFeO3 Nanoparticles

Nanoscale multiferroics are basic model objects for studying polar, magnetic and magnetoelectric properties and mutual couplings. Bismuth-samarium ferrite (Bi1-xSmxFeO3) is a model orthoferrite, whose polar, magnetic and magnetoelectric properties have been studied for the bulk and thin film samples. The properties of Bi1-xSmxFeO3 nanoparticles have been much less studied, despite the nanoparticles can be used in a wide range of applications, such as energy storage, magnetic hyperthermia and advanced nanoelectronics. In this work we performed experimental measurements and analysis of the temperature dependence of the Bi1-xSmxFeO3 nanopowders dielectric properties. Calculations of the ferro-ionic coupling influence on the dielectric properties, domain structure morphology and phase states are performed in the framework of the Ginzburg-Landau-Devonshire-Stephenson-Highland approach. Theoretical results explain the main trends of experimentally observed temperature dependences of the effective dielectric permittivity, which allows us to understand the correlations between the temperature behavior of dielectric properties, domain structure morphology and phase state of Bi1-xSmxFeO3 nanoparticles.

cond-mat.mtrl-sci↗

arXiv2026

Strong coupling between coherent ferrons and cavity acoustic phonons

Coherent ferrons, the quanta of polarization waves, can potentially be hybridized with many other quasiparticles for achieving novel control modalities in quantum communication, computing, and sensing. Here, we theoretically demonstrate a new hybridized state resulting from the strong coupling between fundamental-mode (wavenumber is zero) coherent ferrons and cavity bulk acoustic phonons. Using a van der Waals ferroelectric CuInP2S6 membrane as an example, we predict an ultra-strong ferron-phonon coupling at room temperature, where the coupling strength g_c reaches over 10% of the resonant frequency ω_0. We also predict an in-situ bistable electric-field control of mode-specific ferron-phonon hybridization via ferroelectric switching. We further show that CuInP2S6 allows for reaching the fundamentally intriguing but challenging deep strong coupling regime (i.e., g_c/ω_0>1) near the ferroelectric-to-paraelectric phase transition. Our findings establish the theoretical basis for exploiting coherent ferron as a new contender for hybrid quantum system with strong and highly tunable coherent coupling

cond-mat.mtrl-sci↗

arXiv2026

Role of Oxygen Vacancies in Stabilizing the Orthorhombic Phases of Hf0.5Zr0.5O2 Nanoparticles

In this work we study the stabilization of the orthorhombic phases in small Hf0.5Zr0.5O2 nanoparticles (average size ~ 7 nm) annealed under different oxygen partial pressures. Concentration of the oxygen vacancies, which is determined by annealing conditions, was estimated from the electron paramagnetic resonance spectra and X-ray photoelectron spectroscopy. The fraction of the orthorhombic phases, that is determined by the X-ray diffraction and nuclear magnetic resonance, depends on the concentration of oxygen vacancies. Phenomenological calculations based on Landau-Ginzburg-Devonshire theory considering trilinear coupling between nonpolar, antipolar and polar phonon modes, indicate that chemical strain induced by oxygen vacancies can stabilize the orthorhombic phase o-III with the ferroelectric long-range ordering in small Hf0.5Zr0.5O2 nanoparticles. The theory confirms the stability of ferroelectric polarization in the vacancy-enriched Hf0.5Zr0.5O2 nanoparticles. The increase in the intensity of the dielectric permittivity maximum, observed near 350 - 380 K in the PVDF matrix with the Hf0.5Zr0.5O2 nanoparticles annealed in the CO+CO2 atmosphere, is clearly associated with the increase in oxygen vacancies concentration. The vacancies lead to the defect-induced elastic dipole formation and to the increase in ionic conductivity, which decreases the depolarization field and may induce the ferroelectric-like phase transition in the vacancy-enriched Hf0.5Zr0.5O2 nanoparticles. Due to the interfacial effects the negative capacitance states may be realized in weakly screened and spatially isolated Hf0.5Zr0.5O2 nanoparticles embedded in the PVDF matrix.The present approach based on oxygen-vacancy-induced elastic and screening effects may provide a route for engineering ferroelectric-like states in other nanoscale ferroic oxides.

cond-mat.mtrl-sci↗

arXiv2026

Embedded Ferroelectric Nanoclusters can drive Polarization Reversal in a Non-Ferroelectric Polar Film via the Proximity Effect

Heterogeneous nucleation from defects dominates the electric field required for polarization switching of ferroelectrics. Here, we consider the switching of a nominally non-switchable polar thin film of AlN due to the proximity effect arising from embedded ferroelectric nanoclusters of Al1-xScxN. Using a Landau-Ginzburg-Devonshire thermodynamic approach and finite element modeling, we study the influence of nanocluster shape on polarization switching and domain nucleation emerging in AlN. The ferroelectric nanocluster boundary is modeled as a thin layer transitioning from Al1-xScxN to AlN. We analyze the conditions under which polarization switching in the AlN film occurs at coercive fields significantly lower than its dielectric breakdown field. In the presence of spike-like Al1-xScxN nanoclusters, the proximity effect enables switching of the spontaneous polarization in AlN and significantly reduces the corresponding coercive field. The internal field, which is depolarizing inside the AlN (due to its larger spontaneous polarization) and polarizing within the ferroelectric Al1-xScxN nanoclusters (due to its smaller spontaneous polarization), lowers the potential barrier in the clusters and nucleates nanodomains at the Al1-xScxN-AlN interface, forming localized regions of reversed polarization. Proximity effect can thus provide a pathway towards "thawing" previously "frozen" ferroelectrics through engineered nucleation for memory, actuation and optical technologies.

cond-mat.mtrl-sci↗

arXiv2026

Magnetic properties and charge transport mechanisms in oxygen-deficient HfxZr1-xO2-y nanoparticles

Study of nanoscale hafnia-zirconia physical properties is the key topic in fundamental and applied science. However, charge transport mechanisms and magnetic properties of hafnia-zirconia nanoparticles are very poorly studied both theoretically and experimentally. In this work we observed a superparamagnetic-like and superparaelectric-like response of ultra-small hafnia-zirconia nanoparticles prepared by the solid-state organonitrate synthesis. The EPR spectra of hafnia-zirconia nanopowders reveal the presence of paramagnetic defect centers, which may be hafnium and/or zirconium ions, which trapped an electron near an oxygen vacancy and changed their valence state from the non-paramagnetic +4 to the paramagnetic +3 state. The Raman spectra indicate the decisive role of surface defects, presumably oxygen vacancies, for all studied Zr compositions.At the same time the EELS analysis does not reveal any noticeable concentration of magnetic impurities in the hafnia-zirconia nanopowders, and the X-ray diffraction analysis reveals the dominant presence of the orthorhombic phase. We observed that the quasi-static relative dielectric permittivity of the hafnia-zirconia nanopowders overcomes 10^6 - 10^7 and related the colossal values with the superparaelectric state of the nanoparticles cores induced by the flexo-electro-chemical strains. It has been found that ultra-small hafnia-zirconia nanoparticles reveal posistor effect and relatively large values of accumulated charge. Thus, obtained results open the way for creation of silicon-compatible ferroics oxygen-deficient hafnia-zirconia nanoparticles with superparamagnetic and superparaelectric properties, which may be used in advanced FETs and electronic logic elements.

cond-mat.mtrl-sci↗

arXiv2026

Sizes of Ferroelectricity Appearance and Disappearence in Nanosized Hafnia-Zirconia:Landau-type Theory

Nanosized hafnia-zirconia HfxZr1-xO2 in the form of thin films, multilayers and heterostructures are indispensable silicon-compatible ferroelectric materials for advanced electronic memories and logic devices. The distinctive feature of nanoscale hafnia-zirconia are the critical sizes of ferroelectricity appearance, whereas the critical sizes of ferroelectricity disappearance exist in other ferroelectrics. Using the Landau-Ginzburg-Devonshire free energy functional with higher powers, trilinear and biquadratic couplings of polar, nonpolar and antipolar order parameters, we calculated analytically the strain-dependent critical sizes of the ferroelectricity appearance and disappearance, analyzed how the size effect and mismatch strains influence the phase diagrams and polarization switching barrier in epitaxial HfO2 thin films and nano-islands with the out-of-plane spontaneous polarization. We have shown that the critical thickness/height of out-of-plane spontaneous polarization disappearance is determined by the size dependence of the depolarization field and correlation effects. The critical thickness/height of the ferroelectricity appearance is determined by the size dependence of the effective mismatch strain considering possible appearance of misfit dislocations and lateral relaxion of strains. Derived analytical expressions can be generalized for HfxZr1-xO2 solid solutions, providing that corresponding parameters of the free energy are known from the first principles calculations.

cond-mat.mtrl-sci↗

arXiv2025

Coexistence of Ferroelectric and Relaxor-like Phases in a Multiferroic Solid Solution (1-x)Pb(Fe$_{1/2}$Nb$_{1/2}$)O$_3$-xPbMnO$_3$

Experimental and theoretical studies of unusual polar, dielectric and magnetic properties of room temperature multiferroics, such as perovskites Pb(Fe$_{1/2}$Nb$_{1/2}$)O$_3$ (PFN) and Pb(Fe$_{1/2}$Ta$_{1/2}$)O$_3$ (PFT), are very important. We study the phase composition, dielectric, ferroic properties of the solid solutions PFN and PFT substituted with 5, 10, 15, 20 and 30 % of Mn ions prepared by the solid-state synthesis. The XRD analysis confirmed the perovskite structure of sintered ceramics. Electric measurements revealed the ferroelectric-type hysteresis of electric charge in pure PFN ceramics and in PFN ceramics substituted with (10 - 30)% of Mn. At the same time, the PFN-5% Mn ceramics did not show any ferroelectric properties due to very high conductivity.Temperature dependences of the dielectric permittivity of PFN-10% Mn and PFN-15% Mn ceramics have two pronounced maxima, one of which is relatively sharp and has a weak frequency dispersion; another is diffuse and has a strong frequency dispersion. A further increase in the Mn content up to 20% leads to the right shift in the paraelectric-ferroelectric phase transition temperature, as well as to the strong suppression of the second wide maximum, which transforms into a small diffuse shoulder. An increase in the Mn substitution up to 30% leads to a significant decrease in the dielectric permittivity, left shift of its maximum, and induces a pronounced frequency dispersion of the paraelectric-ferroelectric transition temperature, which is inherent to relaxor-like ferroelectrics.Comparison of the model with experiments reveal the coexistence of the ordered ferroelectric-like and disordered relaxor-like phases in the multiferroic solid solutions PFN-Mn and PFT-Mn.

cond-mat.mtrl-sci↗

arXiv2025

Domain Morphology, Electrocaloric Response, and Negative Capacitance States of Ferroelectric Nanowires Array

We analyzed the domain morphology, electrocaloric response, and negative capacitance states in a one-dimensional array of uniformly oriented, radial symmetric ferroelectric nanowires, whose spontaneous polarization is normal to their symmetry axis. The wires are densely packed between flat electrodes. Using finite element modeling based on the Landau-Ginzburg-Devonshire approach, electrostatics, and elasticity theory, we calculated the distributions of spontaneous polarization, domain structures, electric potential, electric field, dielectric permittivity, and electrocaloric response in the nanowires. Due to size and depolarization effects, the paraelectric and ferroelectric (poly-domain or single-domain) states of the wires can be stable, depending on their radius and the dielectric permittivity of the surrounding medium. It is demonstrated that dipole-dipole interaction between the nanowires determines the stability of the polar (or anti-polar) state in the array when the wire radius is significantly smaller than the critical size of the paraelectric transition in an isolated wire. We reveal that a large region of a mixed state, characterized by poly-domain ferroelectric states with nonzero average polarization inside each wire and zero average polarization of the whole array, can be stable. By selecting the dielectric permittivity of the surrounding medium and the nanowire radius, one can maximize the negative capacitance effect in the capacitor with densely packed wires. It is also possible to achieve maximal enhancement of the electrocaloric response due to size effects in the wires. The underlying physics of the predicted enhancement is the combined action of size effects and the long-range electrostatic interactions between the ferroelectric dipoles in the nanowires and the image charges in the electrodes

cond-mat.mtrl-sci↗

arXiv2025

Colossal dielectric response of HfxZr1-xO2 nanoparticles

We reveal a colossal dielectric response of small (5 - 10 nm) oxygen-deficient HfxZr1-xO2 nanoparticles (x = 1 - 0.4), prepared by the solid-state organonitrate synthesis. The effective dielectric permittivity of the pressed HfxZr1-xO2 nanopowders has a pronounced maximum at 38 - 88 C, which shape can be fitted by the Curie-Weiss type dependence modified for the diffuse ferroelectric-paraelectric phase transition. The maximal value of the dielectric permittivity increases from 1.5*10^3 (for x = 1) to 1.5*10^5 (for x= 0.4) at low frequencies (~4 Hz); being much smaller, namely changing from 7 (for x = 1) to 20 (for x = 0.4) at high frequencies (~500 kHz). The frequency dispersion of the dielectric permittivity maximum position is almost absent, meanwhile the shape and width of the maximum changes in a complex way with increase in frequency. The temperature dependencies of the dielectric permittivity and resistivity are almost mirror-like turned over in respect to each other, which means that all their features, such as position and shape of maxima, plateau, minima and inflexions, almost coincide after the mirror reflection in respect to the temperature axis. These correlations of resistivity and dielectric permittivity are well-described in the Heywang barrier model applied together with the variable range hopping conduction model in semiconducting ferroelectrics. The ferroelectric-like behavior of the small oxygen-deficient HfxZr1-xO2 nanoparticles is expected from the Landau-Ginzburg-Devonshire approach and density functional theory calculations. Obtained results may be useful for developing silicon-compatible functional nanomaterials based on HfxZr1-xO2 nanoparticles.

cond-mat.mtrl-sci↗

arXiv2025

Tip-Based Proximity Ferroelectric Switching and Piezoelectric Response in Wurtzite Multilayers

Proximity ferroelectricity is a novel paradigm for inducing ferroelectricity, where a non-ferroelectric polar material, which is unswitchable with an external field below the dielectric breakdown field, becomes a practically switchable ferroelectric in direct contact with a thin switchable ferroelectric layer. Here, we develop a Landau-Ginzburg-Devonshire approach to study the proximity effect of local piezoelectric response and polarization reversal in wurtzite ferroelectric multilayers under a sharp electrically biased tip. Using finite element modeling we analyze the probe-induced nucleation of nanodomains, the features of local polarization hysteresis loops and coercive fields in the Al1-xScxN/AlN bilayers and three-layers. Similar to the wurtzite multilayers sandwiched between two parallel electrodes, the regimes of "proximity switching" (where the multilayers collectively switch) and the regime of "proximity suppression" (where they collectively do not switch) are the only two possible regimes in the probe-electrode geometry. However, the parameters and asymmetry of the local piezo-response and polarization hysteresis loops depend significantly on the sequence of the layers with respect to the probe. The physical mechanism of the proximity ferroelectricity in the local probe geometry is a depolarizing electric field determined by the polarization of the layers and their relative thickness. The field, whose direction is opposite to the polarization vector in the layer(s) with the larger spontaneous polarization (such as AlN), renormalizes the double-well ferroelectric potential to lower the steepness of the switching barrier in the "otherwise unswitchable" polar layers. Tip-based control of domains in otherwise non-ferroelectric layers using proximity ferroelectricity can provide nanoscale control of domain reversal in memory, actuation, sensing and optical applications.

cond-mat.mtrl-sci↗