Maxwell Displacement Current Research Articles

Measurement of Maxwell's displacement current

The measurement of Maxwell's displacement current has remained a veritable challenge. Here we present a novel approach that allows a detailed verification in a lecture hall-type experiment.

Relation of magnetism and electricity beyond Faraday-Maxwell electrodynamics

A comparison has been performed between the Landau-Dzyaloshinskii-Astrov magnetoelectric effects and the electromagnetic effects caused by the electromagnetic Faraday induction and Maxwell displacement currents. The requirement for the spontaneous violation of symmetry relative to space inversion and time reversion is formulated as the condition for the existence of magnetoelectric effects. An analysis is performed of some results obtained by E.A. Turov both personally and in association with colleagues, which made a significant contribution to the development of the science of magnetoelectricity. These results include the development of the scheme of a simplified symmetry analysis for describing collinear spin structures; the use of this scheme for the invariant expansion of thermodynamic potentials for the magnetic materials with different types of magnetic ordering; the formulation of the microscopic model of magnetoelectricity with the use of the relation between spins and electroactive optical phonons; the study of the phenomena of the enhancement of magnetoelectric effects upon the magnetic resonance; the analysis of the opportunities of electrodipole excitation and of the detection of different signals of magnetic resonance; and the study of the manifestations of magnetoelectric effects in magnetoacoustics and optics.

Maxwell displacement current and nature of Jonsher’s “universal” dynamic response in nanoionics

A new notion—Maxwell displacement current on a potential barrier—is introduced in the structure-dynamic approach of nanoionics for the description of a collective phenomenon: coupled ion transport and dielectric-polarization processes occurring during the ionic space charge formation and relaxation in a nonuniform potential landscape. We simulate the processes: (i) in an electronic conductor (EC)/advanced superionic conductor (AdSIC) ideally polarizable coherent heterojunction, (ii) in a few strained monolayers of a solid electrolyte (SE) located between two AdSICs forming coherent interfaces with SE. We prove that the sum of ionic current over any barrier and Maxwell displacement current through the same barrier is equal to the current of the current generator. A “universal” dynamic response, Reσ*(ω) ∝ ω n (n < ≈1), was found for the frequency-dependent complex conductivity σ*(ω) for case (ii) with an exponential distribution of potential barrier heights in SE. The nature of the phenomenon is revealed. The amplitudes of nonequilibrium ion concentrations (and induced voltages) in the space charge region of SE change approximately as ∝ ω −1. These amplitudes made a main linear contribution to Reσ*(ω). The main deviation from linearity is provided by the cosine of phase shift φ between current and voltage in SE-space charge region but the cosφ depends relatively slightly on ω (near constant loss effect) for coupled ion transport and dielectric-polarization processes.

Conservation of energy and momentum in nonrelativistic plasmas

Conservation laws of energy and momentum for nonrelativistic plasmas are derived from applying Noether's theorem to the action integral for the Vlasov-Poisson-Ampère system [Sugama, Phys. Plasmas 7, 466 (2000)]. The symmetric pressure tensor is obtained from modifying the asymmetric canonical pressure tensor with using the rotational symmetry of the action integral. Differences between the resultant conservation laws and those for the Vlasov-Maxwell system including the Maxwell displacement current are clarified. These results provide a useful basis for gyrokinetic conservation laws because gyrokinetic equations are derived as an approximation of the Vlasov-Poisson-Ampère system.

On Non-conservative Forces and Topological Quantum Phases

A generic non-conservative force, applied to an interferometer particle for a period in the past and then turned off, leaves stationary phase and fringe shifts in the now force-free interferometer. Both Aharonov-Bohm and Aharonov-Casher topological phase and fringe shifts can be created in this way. The specific sources of the non-conservative forces behind Aharonov-Bohm and Aharonov-Casher stationary fringe shifts are, respectively, Faraday induction fields and Maxwell displacement currents, now off.

An Elementary View of Maxwell's Displacement Current

Maxwell's displacement current is addressed in the most basic of terms, starting from Coulomb's law. The aim of this approach is to shed new light on some questions that have dogged the concept, and to help understanding of the key issues involved, in particular, cause and effect, common origin of induced magnetic field and displacement current, differences resulting from a fundamental physical view as opposed to a purely phenomenological view, and finally the appropriate choice of magnetic source terms.

Study of phase transition of two-dimensional ferroelectric copolymer P(VDF-TrFE) Langmuir monolayer by Maxwell displacement current and Brewster angle microscopy

Phase transition of ferroelectric Langmuir monolayers composed of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer with various VDF ratios, was investigated. The thermodynamic, dielectric, and structural properties of these two-dimensional ferroelectric systems were analyzed by coupling surface pressure-area isotherms, Maxwell displacement currents (MDCs), and Brewster angle microscopy (BAM) images. A low-temperature phase transition, specific for the ferroelectric monolayer, was found out with an order-disorder phase transition. The phase transition temperature was dependent on the composition ratio of the copolymer, and the Gibbs free energy reached maximum at this temperature. A negative MDC peak representing dipole moment oriented to the subphase was observed during monolayer compression and disappeared above the order-disorder transition. Interestingly, the BAM images showed decrease of domain size with increase of temperature. These results were well explained based on the order-disorder transition.

Electrical Property of Organic Thin Films for Power Device

Monolayers of lipid on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better understanding of the relationship between the structure and function of the monolayers. Maxwell displacement current (MDC) measurement has been employed to study the dielectric property of Langmuir-films. MDC flowing across monolayers is analyzed using a rod-like molecular model. A linear relationship between the monolayer compression speed alpha and the molecular area A(m). Compression speed alpha was about 30, 40, 50 mm/min. Langmuir-Blodgett (LB) layers of Arachidic acid deposited by LB method were deposited onto slide glass as Y-type film. The structure of manufactured device is Au/Arachidic acid/Al (MIM), the number of accumulated layers are 9-21. Also, we then examined of the Metal-Insulator-Metal (MIM) device by means of I-V. I-V characteristics of the device are measured from -3 to +3 [V]. The insulation property of a thin film is better as the distance between electrodes is larger.

Mixed 2D molecular systems: Mechanic, thermodynamic and dielectric properties

Study of Langmuir monolayers consisting of stearic acid (SA) and dipalmitoylphosphatidylcholine (DPPC) molecules was done by surface pressure–area isotherms ( π– A), the Maxwell displacement current (MDC) measurement, X-ray reflectivity (XRR) and atomic force microscopy (AFM) to investigate the selected mechanic, thermodynamic and dielectric properties based on orientational structure of monolayers. On the base of π– A isotherms analysis we explain the creation of stable structures and found optimal monolayer composition. The dielectric properties represented by MDC generated monolayers were analyzed in terms of excess dipole moment, proposing the effect of dipole–dipole interaction. XRR and AFM results illustrate deposited film structure and molecular ordering.

Study of Domain Shapes and Orientational Structure of Phospholipid Monolayers using Maxwell Displacement Current and Brewster Angle Microscopy

Experiments were conducted on Langmuir monolayers composed of chiral dipalmitoyl-phosphatidylcholine (D-DPPC and L-DPPC) molecules and racemic DPPC (dl-DPPC) molecules by Maxwell displacement current (MDC) measurement and Brewster angle microscopy (BAM) to examine the orientational structure and domain shapes of monolayers. The MDCs generated from chiral DPPC monolayers during monolayer compression resembled each other, indicating that the molecular chirality does not have a direct effect on the generation of MDC. The domain shapes of chiral DPPC monolayers depended on the molecular chirality. On the other hand, the MDC generated from racemic DPPC monolayers was different from that generated from chiral DPPC monolayers at the beginning of the pressure plateau, suggesting an effect of molecular chirality. Interestingly, a spanner-like domain shape of racemic DPPC monolayers was discovered. We suggest that phase separation within the domain by monolayer compression is responsible for the formation of this domain shape.

Study of the Calix[4]resorcinarene−Dopamine Interactions in Monolayers by Measurement of Pressure−Area Isotherms and Maxwell Displacement Currents

The mechanisms of interactions between calix[4]resorcinarene and dopamine in monolayers formed at the air-water interface were studied by analyzing their mechanical, thermodynamic, and electrical properties evaluated from measurements of pressure-area isotherms and Maxwell displacement currents (MDCs). An increased concentration of dopamine in the water subphase resulted in an increase in the area per calix[4]resorcinarene molecule, an increase in the collapse pressure, and a shift in the monolayer phase transitions from the gaseous to the liquid state and from the liquid to the solid state toward higher molecular areas. A contactless method of recording MDCs enabled the monitoring of changes in the charge state of the monolayer-constituting molecules and the determination of a relationship between the phase state of the monolayer and the structural transitions of calix[4]resorcinarene. The changes of the MDC recordings started already in the gaseous state of the monolayer. On the basis of MDC values, we determined the normal component of the dipole moment of calix[4]resorcinarene, as well as that of its complex with dopamine. The dipole moment reached a maximum value of 1040 mD in the region of the phase transition from the liquid to the solid state of the monolayer. The results obtained suggest that the binding of dopamine with calix[4]resorcinarene depends on the orientation of the calixarene molecules in the monolayer. The calix[4]resorcinarene-dopamine interactions were also quantified in terms of the excess of Gibbs free energy, thereby allowing the evaluation of the energy of the calix [4]resorcinarene-dopamine bond, which was in the range from 1.95 to 8.54 kJ/mol depending on the surface pressure. This value implies weak interactions between these molecules.

Domain observation and molecular orientation of chiral dipalmitoylphosphatidylcholine monolayer by Brewster angle microscopy and Maxwell displacement current

To understand the relationship between molecular chirality and electrical properties of monolayers, Maxwell displacement current (MDC) behaviors and domain shapes of chiral DPPC monolayers composed of dextro- ( d-) and levo- ( l-) rotatory molecules at the air–water interface are investigated during monolayer compression using MDC measurement and the Brewster angle microscopy (BAM) system. The experimental results show that for DPPC monolayers of the two pure enantiomers, the π-A isotherms and the MDC behaviors are similar to each other, while the domain patterns of them are mirror shapes of different sizes. This reveals that MDC behaviors due to molecular spontaneous polarization have no relation to chirality but domain shapes closely depend on the molecular chirality. Moreover, the observed domain shapes verify the domain shape theory which was recently developed by Iwamoto et al. [M. Iwamoto, Z.C. Ou-Yang, Phy. Rev. Letts, 93 (2004) 206101].

의료용 초박막 액정의 광배향 제어와 광변위 전류 특성

Maxwell-displacement-current (MDC) measuring technique has been applied for the investigation of monolayers of poly(vinyl alcohol)s bearing azobenzene side-chains (6Az5PVA) mixed with p-pentyl-p`-cyano-biphenyls (5CBs) on a water surface. For mixed monolayers containing trans-form 6Az5PVA and LCs, displacement current due to photo isomerization was not generated with alternative photo-irradiation with UV and svisible light. In contrast, for mixed monolaters containing cis-form 6Az5PVA and LCs, displacement current was generated. Finally, it was found that the alignment layers deposited in cis-form could photoregualte the orientation of LCs.

Study of Gramicidin A−Phospholipid Interactions in Langmuir Monolayers: Analysis of Their Mechanical, Thermodynamical, and Electrical Properties

The mechanisms of interactions between gramicidin A (gA) and dimyristoylphosphatidylcholine (DMPC) in monolayers formed at the air-water interface were studied by analyzing their mechanical, thermodynamical, and electrical properties evaluated from measurements of pressure-area isotherms and of Maxwell displacement currents (MDC). A contactless method of recording MDC enabled us to monitor changes in the charge state of the monolayer-constituting molecules and to find the relation between a phase state of the monolayer and structural transitions of gA. The peptide-lipid interactions were quantified in terms of the excess of Gibbs free energy, excess entropy, as well as the molecular dipole moments at various gA/DMPC molar ratios, at various temperatures (in the gel phase and also in the liquid-crystalline phase of DMPC molecule), and at various surface pressures. It was found that the strongest interactions between gA and DMPC took place at the gA/DMPC molar ratio at around 0.25. At this monolayer composition, the phospholipids, via their carbonyl moieties, dominantly interact with the single helical gA, which mostly stands upright on the surface and is anchored by its C-terminus to the water surface, and prevent the formation of the intertwined helical gA dimers. The optimum ratio was confirmed also by anomalous electrical behavior of electrical dipole moments derived from MDC measurements.

No energy to be extracted from the vacuum**A review of a former article in this journal.

A few years ago a hopeful article (Evans 2000 Phys. Scr.61 513–7) appeared in this journal promising that according to its 15 authors' opinion the pending energy crisis could be solved by ‘extracting energy from the vacuum’. However, in the past years the energy price has grown to unthinkable heights: a reason for having a look at the promised ‘energy from the vacuum’ in (Evans 2000). So we shall do so below and shall arrive at a great disappointment: the 15 authors were in error; their vacuum energy stems from a simple flaw of thinking by misinterpreting the well-known Lorenz term of the classical Maxwell gauge theory. Their miraculous conclusion should have made the authors suspicious, that just the Lorenz term should yield a vacuum current. Surely, its a pity that vacuum currents and vacuum energy in (Evans 2000) have their origin merely in a simple flaw of thinking, and all further speculations for a vacuum energy density are in vain. However, better to return to reality. Quote: of [1]: Great announcements…It is shown that if the Loren(t)z condition is discarded, the Maxwell–Heaviside field equations become the Lehnert equations, indicating the presence of charge density and current density in the vacuum. The Lehnert equations are a subset of the O(3) Yang–Mills field equations. Charge and current density in the vacuum are defined straightforwardly in terms of the vector potential and scalar potential, and are conceptually similar to Maxwell's displacement current, which also occurs in the classical vacuum. A demonstration is made of the existence of a time dependent classical vacuum polarization which appears if the Loren(t)z condition is discarded. Vacuum charge and current appear phenomenologically in the Lehnert equations but fundamentally in the O(3) Yang–Mills theory of classical electrodynamics. The latter also allows for the possibility of the existence of vacuum topological magnetic charge density and topological magnetic current density. Both O(3) and Lehnert equations are superior to the Maxwell–Heaviside equations in being able to describe phenomena not amenable to the latter. In theory, devices can be made to extract the energy associated with vacuum charge and current.

Maxwell displacement current allows to study structural changes of gramicidin A in monolayers at the air–water interface

We applied methods of measurement Maxwell displacement current (MDC) pressure–area isotherms and dipole potential for analysis of the properties of gramicidin A (gA) and mixed gA/DMPC monolayers at an air–water interface. The MDC method allowed us to observe the kinetics of formation of secondary structure of gA in monolayers at an air–water interface. We showed, that secondary structure starts to form at rather low area per molecule at which gA monolayers are in gaseous state. Changes of the MDC during compression can be attributed to the reorientation of dipole moments in a gA double helix at area 7 nm 2/molecule, followed by the formation of intertwined double helix of gA. The properties of gA in mixed monolayers depend on the molar fraction of gA/DMPC. At higher molar fractions of gA (around 0.5) the shape of the changes of dipole moment of mixed monolayer was similar to that for pure gA. The analysis of excess free energy in a gel (18 °C) and in a liquid-crystalline phase (28 °C) allowed us to show influence of the monolayer structural state on the interaction between gA and the phospholipids. In a gel state and at the gA/DMPC molar ratio below 0.17 the aggregates of gA were formed, while above this molar ratio gA interacts favorably with DMPC. In contrast, for DMPC in a liquid-crystalline state aggregation of gA was observed for all molar fractions studied. The effect of formation ordered structures between gA and DMPC is more pronounced at low temperatures.

Ethanol and methanol induced changes in phospholipid monolayer

The main components of cell membranes are phospholipids and proteins. The aim of our study was to examine structural changes of dipalmitoyl-phosphatidylcholine (DPPC) monolayer as a simple model system of a cell membrane in different environments. Pure water, ethanol and methanol solutions were used as subphases of Langmuir films as a membrane models. For detection of changes in charge states of the molecules as well as relation with structural and conformational changes, a contactless method Maxwell's displacement currents (MDC) was used. Behaviour of DPPC molecules on two different subphases is substantialy different. In DPPC monolayer on the subphase of methanol–water, a gradual absorption (incorporation, penetration) of methanol molecules into the layer can appear. In DPPC monolayer on the subphase of ethanol–water adsorption of ethanol molecules on the layer can be observed. The membrane permeability might change. At both subphases (ethanol–water and methanol–water) the elasticity modulus of the monolayer decreases leading to the loss of membrane elasticity.

Electrical Characterization of Thin Layer Materials: Destructive and Non-Destructive Irreversible Processes in Langmuir Films

Summary Well-defined Langmuir-Blodgett films prepared by reproducible technique are still highly attractive for exploitation in investigation of subjects as diverse as chain packing, phase transitions, two-dimensional physics, biosensors and membrane physics. During last 15 years the Maxwell displacement current (MDC) measuring technique was developed for dynamic study of monolayers. In experiment MDC flows through the metal electrode/air gap/Langmuir monolayer/water surface structure. Spontaneous formation of the monolayer was observed and significant differences between destructive and non-destructive processes are discussed.

A Study on the Physical Properties of Functional LB Monolayers

ABSTRACT Photoisomerization in monolayers of a azobenzene dendrimer, was investigated for the first time by means of the absorption spectrum and Maxwell displacement current (MDC) technique. Dendrimers are well-defined macromolecules exhibiting a tree-like structure, first derived by the cascade molecule approach. According to the absorption spectrum, trans-to-cis conversion ratio was estimated to the generation of azobenzene dendrimer. Charge with trans-cis isomerization was also measured by means of MDC technique.

Nano-interface Surface Dielectric Polarization Phenomena: Detection and Application

Nano-interfacial dielectric polarization phenomena were discussed from the viewpoint of electronics, paying attention to the alignment of dipoles and dipolar energy. Firstly, we summarized dielectric polarization phenomena of monolayer comprised of polar molecules, and showed that monolayer is quite different from bulk materials, and the unique dielectric properties of monolayers can be discussed in terms of orientational order parameters. Maxwell-displacement-current (MDC) measurement coupled with optical second harmonic generation (SHG) measurement is shown as an effective way for detecting unique dielectric polarization phenomena of surface monolayers. Then, the importance of dielectric energy is discussed from the viewpoint of monolayer pattern formation and pointed out that the control of dipolar energy can be new pattem formation technology.