Electric Field-induced Changes Research Articles

Electric field-induced volume change in pyro-vanadate-phosphates: Toward an alternative actuator architecture

We discovered large electric-field-induced strain in pyro-vanadate-phosphate Cu2−xZnxV1.8P0.2O7. Distinct from conventionally used piezoelectric materials including lead-zirconate-titanate, this material expands almost isotropically at room temperature when an electric field is applied. This volume change, exceeding 1000 ppm under the field of E = 3900 V/cm, is of the largest class induced by an electric field. The strain is phenomenologically interpreted as electrostriction because it is symmetric about E = 0 and because it obeys a higher term than E-linear such as E squared. The present x-ray diffraction experiments suggest that the applied electric field distorts the crystal lattice, although there is no structural phase transition. This material performs a volume-change-driven actuator function that is distinct from the strain-driven counterpart of piezoelectric materials. The discovery of actuator functionality in a material system with a non-perovskite structure, unlike the actuator materials developed to date, is a major breakthrough for future actuator engineering.

Unlocking guanine’s potential: Unveiling electronic transitions and nanoelectronic applications through electric field modulation

Guanines, key players in DNA and RNA, exist as dynamic keto and enol forms, influencing reactivity and potential applications. This study explores the impact of external electric fields on these forms using computational methods in gas and solvent (water) phases. Analyzing the energy gap, dipole moment, enthalpy, and Gibbs free energy revealed distinct responses. The keto form showed a significant decrease in the energy gap in the presence of an electric field, particularly in water, indicating enhanced reactivity. Conversely, the enol form exhibited a stabilizing effect with increasing electric field strength. Thermodynamic properties highlighted solvent-dependent interactions and electric field-induced changes in electron density distribution. The study further investigated guanine’s potential for nanoelectronics by calculating I-V curves, revealing promising characteristics, especially for the keto form in the aqueous phase. Additionally, the analysis of solvation and cohesive energies provided insights into solute–solvent interactions and intrinsic molecular stability. Overall, this research contributes to understanding how guanine responds to electric fields, paving the way for novel guanine-based materials with potential applications in nanoelectronics.

Electric field-induced changes in photoluminescence and Raman spectra of MoS2 on PVA-coated conductive substrate with nematic liquid crystals: a combined numerical and experimental study

Electric field-induced changes in photoluminescence and Raman spectra of MoS2 on PVA-coated conductive substrate with nematic liquid crystals: a combined numerical and experimental study

In-situ electric field-tailored exchange bias in the manganite/ferroelectric multiferroic heterostructures

The application of electric field-induced magnetic structure changes has significantly advanced nonvolatile data storage with ultralow energy consumption, as well as spintronics and quantum computing processes. In artificial perovskite oxide multiferroic structures composed of ferromagnetic and ferroelectric layers, the evolution of magnetic phases and ferroelectric domains often contribute to the magnetoelectric coupling. To fully understand the mechanisms behind electric field-induced changes in magnetic structures and enable the miniaturization of magnetoelectric devices, it is crucial to achieve local ferroelectric domain-triggered ferromagnetic evolution. In this study, we have fabricated La0.7Ca0.3MnO3/Pb(Zr0.52Ti0.48)O3 (LCMO/PZT) heterostructures, where the magnetic phase separation of LCMO and the ferroelectric domain of PZT can be modulated by substrates and piezoelectric force microscopy, respectively. Our experiments demonstrate that by switching the polarization states of PZT, we can observe electric field control of the magnetic exchange bias effect through changes in the phase separation of the LCMO layer. These results contribute to the development of magnetoelectric devices with enhanced properties and offer valuable insights for future design strategies.

Electric field-induced morphological changes on polymer surface using phase-field model

Electric field-induced morphological changes on polymer surface using phase-field model

Tunable electronic properties, migration mechanism and quantum capacitance of Zr2CO2 monolayer by electric filed effects

MXenes have received a lot of attention because of the excellent structure and outstanding properties. Electric field-induced changes in electronic properties and quantum capacitance of Zr2CO2 monolayer are explored theoretically. The negative cohesive energy confirms the stability of Zr2CO2 monolayer under external electric field (EEF). Zr2CO2 undergoes the indirect-direct transition at 0.4 V/Å, and the semiconductor-metal transition at 0.5 V/Å. Band gap is not sensitive to the smaller EEF, but sensitive to larger EEF. All systems are all potential cathode materials in ionic/organic system. Zr2CO2 under 0.5 V/Å is a potential anode electrode in aqueous system. The quantum capacitances of Zr2CO2 under EEF in whole voltage at 233 K and 353 K are further explored. The widen voltage changes Zr2CO0.78F1.11(OH)0.11 from anode material in aqueous system to cathode material in ionic/organic system. The spatial charge distribution of Zr2CO2 MXene is also analyzed.

Study and Simulation of the Electric Field-Induced Spin Switching in PZT/NiFe/CoFe Nanostructured Composites

In this work, we have studied the electric field-induced spin switching in the PZT/NiFe/CoFe nanostructured composites by sputtering ferromagnetic layers on a horizontal polarized piezoelectric PZT substrate. The electric field-induced change in the magnetization orientation was investigated systematically using a vibrating sample magnetometer and analytical simulations. The results revealed that electric field applications could indirectly control the magnetic spin orientations. Moreover, the magnetization change depends not only on the electric field but also on the direction of the electric field applying against the magnetic field. The images of magnetic moment orientations under various electric field applications are modeled by the Monte Carlo and NMAG simulations. In particular, a critical electric field of Ecr ≈ 300 kV/cm, which makes a 90o spin switching, was determined. These results are proposed to offer an opportunity for random access memory applications.

Room-Temperature Electrical Field-Enhanced Ultrafast Switch in Organic Microcavity Polariton Condensates.

Integrated electro-optical switches are essential as one of the fundamental elements in the development of modern optoelectronics. As an architecture for photonic systems exciton polaritons, hybrid bosonic quasiparticles that possess unique properties derived from both excitons and photons, have shown much promise. For this system, we demonstrate a significant improvement of emitted intensity and condensation threshold by applying an electric field to a microcavity filled with an organic microbelt. Our theoretical investigations indicate that the electric field makes the excitons dipolar and induces an enhancement of the exciton-polariton interaction and of the polariton lifetime. Based on these electric field-induced changes, a sub-nanosecond electrical field-enhanced polariton condensate switch is realized at room temperature, providing the basis for developing an on-chip integrated photonic device in the strong light-matter coupling regime.

Electric field-induced functional changes in electrode-immobilized mutant species of human cytochrome c

Post-translational modifications and naturally occurring mutations of cytochrome c have been recognized as a regulatory mechanism to control its biology. In this work, we investigate the effect of such in vivo chemical modifications of human cytochrome c on its redox properties in the adsorbed state onto an electrode. In particular, tyrosines 48 and 97 have been replaced by the non-canonical amino acid p-carboxymethyl-L-phenylalanine (pCMF), thus mimicking tyrosine phosphorylation. Additionally, tyrosine 48 has been replaced by a histidine producing the natural Y48H pathogenic mutant. Thermodynamics and kinetics of the interfacial electron transfer of wild-type cytochrome c and herein produced variants, adsorbed electrostatically under different local interfacial electric fields, were determined by means of variable temperature cyclic film voltammetry. It is shown that non-native cytochrome c variants immobilized under a low interfacial electric field display redox thermodynamics and kinetics similar to those of wild-type cytochrome c. However, upon increasing the strength of the electric field, the redox thermodynamics and kinetics of the modified proteins markedly differ from those of the wild-type species. The mutations promote stabilization of the oxidized form and a significant increase in the activation enthalpy values that can be ascribed to a subtle distortion of the heme cofactor and/or difference of the amino acid rearrangements rather than to a coarse protein structural change. Overall, these results point to a combined effect of the single point mutations at positions 48 and 97 and the strength of electrostatic binding on the regulatory mechanism of mitochondrial membrane activity, when acting as a redox shuttle protein.

Inhomogeneous electric field-induced structural changes in soft lead zirconate titanate ferroelectric ceramics

Under the application of an external voltage, high electric field concentrations can develop around the interdigitated electrode edges inside multilayer ceramic actuators (MLCAs). The spatial distribution of the local electrical field can create local inhomogeneity in the electromechanical response. To investigate the complex field inhomogeneity in MLCAs, partially electroded Nb-doped PbZrxTi1-xO3 samples were investigated via synchrotron-based high-energy X-ray diffraction (XRD) as a function of applied electric field. These in situ experiments allowed us to probe the structural changes as a function of position relative to the electrode edge and calculate the local degree of domain alignment, from which the local electric field directions were inferred. The domain switching behavior, both in amplitude and orientation, was found to be spatially dependent across the inactive regions in partially electroded samples. Specifically, the degree of domain alignment and field-induced phase transitions are amplified near the electrode edge. The orientation-dependent phase transitions are also amplified for the tetragonal composition near the morphotropic phase boundary (MPB), i.e., the Nb-doped PbZr0.53Ti0.47O3 composition. Finite element analysis (FEA) shows spatially-dependent, inhomogeneous electric field distributions in the partial-electrode samples, which closely match the experimentally inferred local electric field directions from XRD. The correlation of FEA and experimental data from XRD corroborates that the ferroelectric domain orientation distributions are being directed, primarily, in the direction of the electric field.

A lateral electric field inhibits gel-to-fluid transition in lipid bilayers.

We report evidence of lateral electric field-induced changes in the phase transition temperatures of lipid bilayers. Our atomic scale molecular dynamics simulations show that a lateral electric field increases the melting temperatures of DPPC, POPC and POPE bilayers. Remarkably, these shifts in the melting temperatures are only induced by lateral electric fields, and not normal electric fields. This mechanism could provide new mechanistic insights into lipid-lipid and lipid-protein interactions in the presence of endogenous and exogenous electric fields.

Electroresistance in multipolar antiferroelectric Cu2Se semiconductor

Electric field-induced changes in the electrical resistance of a material are considered essential and enabling processes for future efficient large-scale computations. However, the underlying physical mechanisms of electroresistance are currently remain largely unknown. Herein, an electrically reversible resistance change has been observed in the thermoelectric α-Cu2Se. The spontaneous electric dipoles formed by Cu+ ions displaced from their positions at the centers of Se-tetrahedrons in the ordered α-Cu2Se phase are examined, and α-Cu2Se phase is identified to be a multipolar antiferroelectric semiconductor. When exposed to the applied voltage, a reversible switching of crystalline domains aligned parallel to the polar axis results in an observed reversible resistance change. The study expands on opportunities for semiconductors with localized polar symmetry as the hardware basis for future computational architectures.

Ultrafast control of electronic states by a terahertz electric field pulse in the quasi-one-dimensional organic ferroelectric (TMTTF)2PF6

A strong terahertz pulse is effective for controlling the macroscopic polarization in ferroelectrics. In the present study, we investigated the response of an organic molecular compound, namely ${(\mathrm{TMTTF})}_{2}\mathrm{P}{\mathrm{F}}_{6}$ (TMTTF: tetramethyltetrathiafulvalene), to a strong electric field using terahertz pulse-pump optical-reflectivity probe spectroscopy. This compound undergoes a transition from Mott insulator to charge-order insulator with lowering temperature, and exhibits electronic ferroelectricity in the charge-order phase. When the terahertz pulse is applied in the Mott-insulator phase, an ultrafast reflectivity change proportional to the square of the electric field waveform of the terahertz pulse emerges, which is attributed to the generation of charge disproportionation in each dimer and the resultant creation of macroscopic polarization. When the terahertz pulse is applied in the charge-order phase, an ultrafast reflectivity change proportional to the electric field waveform of the terahertz pulse is observed, which originates from the modulation of the original charge disproportionation and polarization. These ultrafast reflectivity changes can be ascribed to purely electronic responses. In the midinfrared region, where totally symmetric $({a}_{\mathrm{g}})$ modes of intramolecular vibrations coupled with intermolecular charge transfers exist, a large reflectivity change is commonly observed in the Mott-insulator and charge-order phases. To interpret this feature, we constructed a model that incorporates a charge-transfer transition and ${a}_{g}$-mode intramolecular vibrations. The analyses of the results with this model revealed that the change in the reflectivity spectrum by the terahertz electric field can be explained by the energy shift of the charge-transfer transition caused by the electric field-induced change of charge disproportionation in each dimer, and the transfer of the spectral weight from the intradimer charge-transfer (CT) transition to the interdimer CT transition resulting from the weakening of the dimerization. Our model can be used to analyze the optical responses to electric fields in various organic molecular compounds with electron-intramolecular vibration couplings.

Electric field-induced photoluminescence quenching in Pr-doped BNT ceramics across the MPB region

Piezophotonics is a great interesting field of physics that has led to a number of important technologies, such as light source, smart sensors, and mechatronics. In this work, we reported Pr-doped (Bi0·5Na0.5)TiO3-based lead-free ceramics with strong red photoluminescence emission and large strain response (d33∗ = 460 pm/V, S = 0.32 %). The PL emission can be quenched by decreasing the intensity by 93 % after electrical polarization (E = 50 kV/cm). The local structure and electric field-induced structural changes were systematically investigated to reveal the significant distinction in photoluminescence properties caused by electrical polarization. The results indicated that polarization treatment eliminates the structural inhomogeneities and establishes a long-range ferroelectric tetragonal and rhombohedral distortion. The crystal structure transformed irreversibly from a non-ergodic to a normal ferroelectric state. PL quenching originated from the decreased distortion of octahedral due to the transition from a non-ergodic state to a highly ordered symmetrical structure. Meanwhile, the enlarged domain structure contributed to the photoluminescence quenching effect. Our findings demonstrate that an electric field can be a robust tool for adjusting the photoluminescence property and provide insights into the relationship between the structure and PL properties of BNT-based ceramics under an external stimulus.

(Nanocarbons Division Best Poster Award - 3rd Place) Reversible Quenching of Graphene Oxide Photoluminescence Under the External Electric Field

With the advent of graphene, there has been an interest in utilizing this material and its derivative, graphene oxide (GO) for novel applications in nanodevices such as bio and gas sensors, solid-state supercapacitors and solar cells. Although GO exhibits lower conductivity and structural stability, it possesses an energy band gap that enables fluorescence emission in the visible/near infrared leading to a plethora of optoelectronic applications. In order to allow fine-tuning of its optical properties in the device geometry, new physical techniques are required that, unlike existing chemical approaches, yield substantial alteration of GO structure. Such a desired new technique is one that is electronically controlled and leads to reversible changes in GO optoelectronic properties. In this work, we for the first time investigate the methods to controllably alter the optical response of GO with the electric field and provide theoretical modeling of the electric field-induced changes. Field-dependent GO emission is studied in bulk GO/polyvinylpyrrolidone films with up to 6% reversible decrease under 1.6 V m−1 electric fields. On an individual flake level, a more substantial over 50% quenching is achieved for select GO flakes in a polymeric matrix between interdigitated microelectrodes subject to two orders of magnitude higher fields. This effect is modeled on a single exciton level by utilizing Wentzel, Kremer, and Brillouin approximation for electron escape from the exciton potential well. In an aqueous suspension at low fields, GO flakes exhibit electrophoretic migration, indicating a degree of charge separation and a possibility of manipulating GO materials on a single-flake level to assemble electric field-controlled microelectronics. As a result of this work, we suggest the potential of varying the optical and electronic properties of GO via the electric field for the advancement and control over its optoelectronic device applications.

Energy Component Analysis of Electric Field-Induced Shape Change in Water Nanodroplets

We present a comprehensive classical molecular dynamics study of water nanodroplets under the influence of an externally applied electric field. Our simulations cover a wide range of droplet sizes and electric field strengths, which allows for a thorough exploration of the structural and energetic behavior of nanodroplets in the presence of an external electric field. Our analysis reveals the molecular-level mechanism behind the shape extension of a nanodroplet from a spheroid to a highly prolate ellipsoid as the propensity of the water dipoles to align with the electric field while simultaneously restructuring to minimize the dipole–dipole interaction energy. We also develop a quantitative theory that describes the energetic landscape for the nanodroplet shape extension process and allows predictions of the nanodroplet behavior based on its initial size and the strength of the applied field.

Electric field-induced switching among multiple conductance pathways in single-molecule junctions.

Here, we report the switching among multiple conductance pathways achieved by sliding the scanning tunneling microscope tip among different binding sites under different electric fields. With an increase in the electric field, high molecular conductance states appear, suggesting the formation of different configurations in single-molecule junctions. The switch can be operated in situ and reversibly, which is also confirmed by the apparent conductance conversion in I-V measurements. Theoretical simulations also agree well with the experimental results, which implies that the electric field enables the possibility to trigger switching in single-molecule junctions.

Imaging the valley and orbital Hall effect in monolayer MoS2.

The topological properties of a material's electronic structure are encoded in its Berry curvature, a quantity which is intimately related to the transverse electrical conductivity. In transition metal dichalcogenides with broken inversion symmetry, the nonzero Berry curvature results in a valley Hall effect. In this paper we identify a previously unrecognized consequence of Berry curvature in these materials: an electric field-induced change in the electrons' charge density orientation. We use first principles calculations to show that measurements of the electric field-induced change in the charge density or local density of states in MoS2 can be used to measure its energy-dependent valley and orbital Hall conductivity.

Electric field quenching of graphene oxide photoluminescence

With the advent of graphene, there has been an interest in utilizing this material and its derivative, graphene oxide (GO) for novel applications in nanodevices such as bio and gas sensors, solid-state supercapacitors and solar cells. Although GO exhibits lower conductivity and structural stability, it possesses an energy band gap that enables fluorescence emission in the visible/near infrared leading to a plethora of optoelectronic applications. In order to allow fine-tuning of its optical properties in the device geometry, new physical techniques are required that, unlike existing chemical approaches, yield substantial alteration of GO structure. Such a desired new technique is one that is electronically controlled and leads to reversible changes in GO optoelectronic properties. In this work, we for the first time investigate the methods to controllably alter the optical response of GO with the electric field and provide theoretical modeling of the electric field-induced changes. Field-dependent GO emission is studied in bulk GO/polyvinylpyrrolidone films with up to 6% reversible decrease under 1.6 V µm−1 electric fields. On an individual flake level, a more substantial over 50% quenching is achieved for select GO flakes in a polymeric matrix between interdigitated microelectrodes subject to two orders of magnitude higher fields. This effect is modeled on a single exciton level by utilizing Wentzel, Kremer, and Brillouin approximation for electron escape from the exciton potential well. In an aqueous suspension at low fields, GO flakes exhibit electrophoretic migration, indicating a degree of charge separation and a possibility of manipulating GO materials on a single-flake level to assemble electric field-controlled microelectronics. As a result of this work, we suggest the potential of varying the optical and electronic properties of GO via the electric field for the advancement and control over its optoelectronic device applications.

Electric Field Quenching of Graphene Oxide Photoluminescence

With the advent of graphene, there has been an interest in utilizing this material and its derivative, graphene oxide (GO) for novel applications in biotechnology, electronics, photonics, materials and environmental science. Although GO exhibits lower conductivity and structural stability, it possesses an energy band gap that enables fluorescence emission in the visible/near infrared leading to a plethora of optoelectronic applications. In order to enable fine-tuning of its optical properties in the device geometry, new physical techniques are required that unlike existing chemical approaches yielding substantial alteration of GO structure, enable electronically-controlled and, ideally, reversible changes in GO optoelectronic properties. In this work, we for the first time investigate the methods to controllably alter the optical response of GO with the electric field and provide theoretical modelling of the electric field-induced changes. Field-dependent GO emission is studied in bulk GO/PVP films with up to 6% reversible decrease under 1.6 V/µm electric fields. On an individual flake level a more substantial 50% quenching is achieved for select GO flakes in polymeric matrix between interdigitated microelectrodes subject to two orders of magnitude higher fields. This effect is modelled on a single exciton level by utilizing WKB approximation for electron escape form the exciton potential well. In an aqueous suspension at low fields GO flakes exhibit electrophoretic migration indicating a degree of charge separation and a possibility of manipulating GO materials on a single-flake level to assemble electric field-controlled microelectronics. As a result of this work, we suggest the potential of varying the optical and electronic properties of GO via the electric field for the advancement and control over its optoelectronic device applications.