Magnetoelectric effect in layered disk-shaped magnetostrictive–piezoelectric structures: Theory and experiment

Theoretical and experimental studies of the magnetoelectric effect in a disk-shaped magnetostrictive–piezoelectric structure in the electromechanical resonance region are presented. An expression for the magnetoelectric voltage coefficient is derived based on the simultaneous solution of elastodynamic and electrostatic equations separately for magnetostrictive and piezoelectric layers. The conditions at the interface were taken into account based on the premise that the interaction between layers is implemented by shear. It is shown that the inhomogeneity of the voltage and strain distribution over the sample thickness, caused by the interface, leads to a significant contribution to the effect in the case of thick layers. The theoretical and experimental dependences of the frequency characteristic of the effect are presented for the permendur–lead zirconate-titanate–permendur structure. The theoretical calculations are in good agreement with experimental data.     

Propagation of SH waves in layered functionally gradient piezoelectric–piezomagnetic structures

Abstract

The propagation of SH waves is studied in two bonded semi-infinite material, one piezoelectric and the other piezomagnetic. Both materials are functionally gradient materials. The material properties of the two materials vary in two directions, one parallel to the interface and the other perpendicular to the interface. The dispersion relations are obtained in explicit forms for different forms of the non-homogeneities. The effects of gradient variation about material constants on the frequency of SH waves and on the wave numbers are shown graphically.     

Pyroelectric effect in layered magnetoelectric PZT/Ni–Zn ferrite composites

The electric response of layered 2-2 connectivity magnetoelectric composites to the action of a modulated heat flow, which is detected by a dynamic method, is studied. The kinetics of the pyroelectric response of the composite material to a pulsed thermal action is calculated. The experimental results and calculation data suggest that a modulated heat action induces a signal due to both the pyroelectric and piezoelectric effects. The latter effect is caused by the mechanical interaction of the layers of lead zirconate titanate ceramic and nickel–zinc (Ni–Zn) ferrite.     

Use of ɛ expansions in the theory of the gravitational effect

The equations of state found by the expansion method by Brézin, Wallace, and Wilson and Avdeeva and Migdal are applied to the investigation of the gravitational effect in the critical region. As a result, expansions are obtained for the numerical coefficients in the asymptotic behaviors of the scale functions of these equations. The results of the calculation of the coefficients are compared with available experimental data for a number of liquids and magnets.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 77–81, May, 1980.     

Verification of the stability criterion of inverse algorithms for layered sea bottom

In this paper,two inverse algorithms were used to infer the impedanceprofile of the layered bottom in a cooling-water pool.The error by twoalgorithms increased dramatically and leading to overflow in computation.Both inverse results were quite close to the measured data if the recorded datahad been corrected by a stability criterion.     

To the theory of isotope effect in the thermodynamics of “Classical” crystals

Based on general expressions for quantum contributions to the free energy of a statistical system, an approach is developed making it possible to carry out a complete theoretical analysis of the equilibrium thermodynamic characteristics of argon-type crystals as a function of the isotopic mass. The theory is based on independently calculated (in fact, without fitting parameters) one-particle and two-particle distribution functions of the classical crystal and permits one to quantitatively describe the data on the lattice parameters of isotope crystals obtained from numerical experiments. It is pointed out that real experiments are needed to study the isotope effect in crystals of noble gases, especially in view of the fact that, according to the literature data, xenon undergoes an fcc-hcp phase transition under increased pressure.     

An inverse algorithm for reconstructing the acoustic parameters of layered medium

I.IntroductionThcinvcrsescattcringprob1cmisbasicinarcassuchasradar,sonar,geophysica1explora-honandnondestructivctesting.Whenthescatteringobjectisaconstitutiveparametersvaryinacontinuousmannerandtheinvcrseproblcmistodctcrmineoneormoreoftheseparametcrsfromtheobserveddata.Muchofthcpreviousworkonthisproblcmforthecaseofp1anewaveatnormalincidencchasconsistcdofderivingaSchr6dingerequationfromthebasicacousticandstrcss-straincquations,andthenreconstruchngthepotentialappearinginthisequationbyusingtheGe…     

Euler–Heisenberg effective action and magnetoelectric effect in multilayer graphene

The low energy effective field model for the multilayer graphene (at ABC stacking) is considered. We calculate the effective action in the presence of constant external magnetic field B$B$ (normal to the graphene sheet). We also calculate the first two corrections to this effective action caused by the in-plane electric field E$E$ at E/B?1$E/B?1$ and discuss the magnetoelectric effect. In addition, we calculate the imaginary part of the effective action in the presence of constant electric field E$E$ and the lowest order correction to it due to the magnetic field (B/E?1$B/E?1$).     

The Aharonov–Bohm effect in scattering theory

The Aharonov–Bohm effect is considered as a scattering event with nonrelativistic charged particles of the wavelength which is less than the transverse size of an impenetrable magnetic vortex. The quasiclassical WKB method is shown to be efficient in solving this scattering problem. We find that the scattering cross section consists of two terms, one describing the classical phenomenon of elastic reflection and another one describing the quantum phenomenon of diffraction; the Aharonov–Bohm effect is manifested as a fringe shift in the diffraction pattern. Both the classical and the quantum phenomena are independent of the choice of a boundary condition at the vortex edge, providing that probability is conserved. We show that a propagation of charged particles can be controlled by altering the flux of a magnetic vortex placed on their way.     

Two-dimensional and layered structures in the discrete φ4 model

The properties of phase transitions in two-dimensional and layered systems are investigated on the basis of a discrete φ⁴ model by numerical and analytical methods. The only parameter a of the discrete φ⁴ model determines the behavior of the system and makes it possible to investigate phase transitions ranging from transitions of the displacement type (a → +0) to order-disorder type (a → +∞). The behavior of a two-dimensional system is investigated in a wide range of values of the parameter a. The temperature dependences of the squared order parameter η²(T) and the phase transition temperature T _c as a function of the thickness N of the system are obtained for three characteristic values of the parameter a using the Monte Carlo method. The properties of phase transitions in the discrete φ⁴ model are investigated on the basis of the mean-field approximation and the independent-mode approximation. The results obtained in the numerical experiments are compared with the analytical approximations. It is shown that the mean-field approximation qualitatively describes the behavior of the phase-transition temperature T _c as a function of the thickness N of the system for a wide range of values of the parameter a, and the independent-mode approximation describes quantitatively, to within 5%, the results of the numerical simulation for small values of a.     

A Curie–Weiss theory of the continuum Widom–Rowlinson model

A version of the continuum Widom–Rowlinson model is introduced and studied. It is a two-component gas of point particles placed in ${\mathbf{R}}^d$ in which like particles do not interact and unlike particles contained in a given vessel of volume V repel each other with intensity $a/V$. This model is thermodynamically equivalent to a one-component gas with multi-particle interaction. For both models, a rigorous theory of a phase transition is presented and the ways of its construction in the framework of the grand canonical formalism are outlined.     

Complex impedance analyses and magnetoelectric effect in ferrite–ferroelectric composite ceramics

Magnetoelectric (ME) composites yBa_0.8Pb_0.2TiO₃–(1−y$1-y$)CuFe₂O₄ are prepared by ceramic method. The component phases are prepared from two different routes, viz. CuFe₂O₄ (ferrite phase) is prepared by oxalate precursor route and Ba_0.8Pb_0.2TiO₃ (ferroelectric phase) by solid-state reaction route. No intermediate phases are observed in the composites containing these ferrite and ferroelectric phases. ME conversion factor (measure of ME effect) is found to be enhanced compared to those reported in the composites, in which the component phases were prepared by only one route, i.e. solid-state reaction route. The results on ME conversion are well accounted by measuring the complex impedance and analyzing their Nyquist plots.     

A generalization of Poisson–Nijenhuis structures

We generalize Poisson–Nijenhuis structures. We prove that on a manifold endowed with a Nijenhuis tensor and a Jacobi structure which are compatible, there is a hierarchy of pairwise compatible Jacobi structures. Furthermore, we study the homogeneous Poisson–Nijenhuis structures and their relations with Jacobi structures.     

Study of Yang–Mills–Chern–Simons theory in presence of the Gribov horizon

The two-point gauge correlation function in Yang–Mills–Chern–Simons theory in three dimensional Euclidean space is analysed by taking into account the non-perturbative effects of the Gribov horizon. In this way, we are able to describe the confinement and de-confinement regimes, which naturally depend on the topological mass and on the gauge coupling constant of the theory.     

Equivalent circuit model including magnetic and thermo sources for the thermo–magneto–electric coupling effect in magnetoelectric laminates

The nonlinear thermo–magneto–mechanical magnetostrictive constitutive and the linear thermo–mechanical-electric piezoelectric constitutive are adopted in this paper. The bias magnetic field and ambient temperature are equivalent to a magnetic source and a thermo source, respectively. An equivalent circuit, which contains a magnetic source and a thermo source at the input, for the thermo–magneto–electric coupling effect in magnetoelectric(ME) laminates, is established. The theoretical models of the output voltage and static ME coefficient for ME laminates can be derived from this equivalent circuit model. The predicted static ME coefficient versus temperature curves are in excellent agreement with the experimental data available both qualitatively and quantitatively. It confirms the validity of the proposed model. Then the models are adopted to predict variations in the output voltages and ME coefficients in the laminates under different ambient temperatures, bias magnetic fields, and the volume ratios of magnetostrictive phases. This shows that the output voltage increases with both increasing temperature and increasing volume ratio of magnetostrictive phases; the ME coefficient decreases with increasing temperature; the ME coefficient shows an initial sharp increase and then decreases slowly with the increase in the bias magnetic field, and there is an optimum volume ratio of magnetostrictive phases that maximize the ME coefficient.This paper can not only provide a new idea for the study of the thermo–magneto–electric coupling characteristics of ME laminates, but also provide a theoretical basis for the design and application of ME laminates, operating under different sensors.     

Wiedemann effect of Fe—Ga based magnetostrictive wires

(Fe83Ga17)98Cr2 wires each with a diameter of 0.7 mm are prepared by hot swaging and warm drawing from the casting rods directly,because the ductility of Fe83Ga17 alloy is improved by adding Cr element.The Wiedemann twists and dependences on magnetostrictions of Fe83Ga17 and(Fe83Ga17)98Cr2 wires are investigated.The largest observed Wiedemann twists of 245 s·cm-1 and 182 s·cm-1 are detected in the annealed Fe83Ga17 and(Fe83Ga17)98Cr2 wires,respectively.The magnetostrictions of the annealed Fe83Ga17 and(Fe83Ga17)98Cr2 wires are 160 ppm and 107 ppm,respectively.The maximum of the Wiedemann twist increases with magnetostriction increasing.However the magnetostriction is just one important factor that affects the Wiedemann effect of alloy wire,and the relationship between magnetostriction and Wiedemann effect is a complex function rather than a simple function.     

Dynamic response of converse magnetoelectric effect in a PMN-PT-based multiferroic heterostructure

A multiferroic heterostructure, consisting of a 25 μm thick Metglas® ribbon affixed to a lead magnesium niobate–lead titanate (PMN-PT) crystal, was systemically studied to investigate the time response of converse magnetoelectric coupling under the application of electric fields at low frequencies (0.05<f<10 Hz). This multiferroic heterostructure exhibits a considerably strong converse magnetoelectric effect, CME=?80%, where CME=[M(E)?M(0)]/M(0), and a converse ME coupling constant, A=22.5 Oe-cm/kV, at frequencies below 1 Hz and near saturation electric polarization. A switching time (t _s), representing the response time of the CME coupling, is measured to be 0.6 seconds for this heterostructure under the application of instantaneous electric fields. The switching time results in significant influences on the magnetoelectric effect especially at frequencies higher than 2 Hz. The dynamic response of CME coupling is predominantly determined by ferroelectric relaxation within the PMN-PT crystal, as opposed to the magnetic relaxation of the Metglas® ribbon. A model was used to describe the dynamic behavior of CME coupling in disordered systems such as PMN-PT.     

On the effect of lead concentration on the kinetics of contact melting in the Sn–Pb–Bi system in the presence of electromigration

It is determined by electron microscopy that the contact layer in the Sn–(Bi + 30 wt % Pb) system contains separate solid inclusions, while the contact layer in the Sn–(Bi + 40 wt % Pb) system is microheterogeneous. The observed structural states of alloys in the contact layers are explained by a change in the concentration of the initial contacting samples. The effect of the alloy structure and electromigration on the kinetics of contact melting is found.     

Classical theory of atom–surface scattering: The rainbow effect

The scattering of heavy atoms and molecules from surfaces is oftentimes dominated by classical mechanics. A large body of experiments have gathered data on the angular distributions of the scattered species, their energy loss distribution, sticking probability, dependence on surface temperature and more. For many years these phenomena have been considered theoretically in the framework of the “washboard model” in which the interaction of the incident particle with the surface is described in terms of hard wall potentials. Although this class of models has helped in elucidating some of the features it left open many questions such as: true potentials are clearly not hard wall potentials, it does not provide a realistic framework for phonon scattering, and it cannot explain the incident angle and incident energy dependence of rainbow scattering, nor can it provide a consistent theory for sticking. In recent years we have been developing a classical perturbation theory approach which has provided new insight into the dynamics of atom–surface scattering. The theory includes both surface corrugation as well as interaction with surface phonons in terms of harmonic baths which are linearly coupled to the system coordinates. This model has been successful in elucidating many new features of rainbow scattering in terms of frictions and bath fluctuations or noise. It has also given new insight into the origins of asymmetry in atomic scattering from surfaces. New phenomena deduced from the theory include friction induced rainbows, energy loss rainbows, a theory of super-rainbows, and more. In this review we present the classical theory of atom–surface scattering as well as extensions and implications for semiclassical scattering and the further development of a quantum theory of surface scattering. Special emphasis is given to the inversion of scattering data into information on the particle–surface interactions.     

Faddeev–Jackiw quantization of the higher derivative Chern–Simons gauge theory in the first-order formalism

We analyse the physical constraints of the higher derivative Chern–Simons gauge model by means of Faddeev–Jackiw symplectic approach in the first-order formalism. Within such framework, we systematically determine the zero-mode structure of the corresponding symplectic matrix. In addition, we calculate the Faddeev–Jackiw quantum brackets by choosing appropriate gauge-fixing conditions and evaluate the determinant of the non-singular symplectic matrix as well as the transition-amplitude. Finally, we present a detailed Hamiltonian analysis using Dirac–Bergmann algorithm method and show that the Dirac brackets coincide with the FJ brackets when all the second-class constraints are treated as zero equations.