Search results for "Polarization density"

Coherent Manipulation of Polarization in Mixed-Valence Compounds by Electric Pulse via Landau–Zener Transitions

2012

In this contribution, we predict and theoretically investigate the effects of the electric field pulse in mixed valence (MV) dimers. These systems exhibit bistability with a large internal dipole moment mediated by the itinerant electron trapped by the vibronic coupling. In this sense, they are similar to single molecular magnets (SMMs) that are bistable systems possessing large long-living magnetization and exhibiting Landau−Zener (LZ) transitions. We propose a scheme for a controllable LZ tunnelling in MV systems that provides also a possibility to control the dipole moment of a dimeric MV unit. It is supposed that the static electric field initially polarizes the system, and then the uni…

Dielectric polarization and polarizability of 1-pentanol+n-octane mixtures from static dielectric constant and refractive index data at 0,25 and 45�C

1990

Static dielectric constants and refractive indices of 1-pentanol+n-octane mixtures were measured in the temperature range between 0 and 45°C. Data discussed in terms of Kirkwood correlation factor and Lorentz-Lorenz molar refractivity give information on the short range intermolecular interactions between the components. The role played by the nonpolar n-octane in the destruction of 1-pentanol oligomers is also pointed out.

Multiferroic BiFeO<inf>3</inf> for conductance control at the LaAlO<inf>3</inf>/SrTiO<inf>3</inf>-interface

2015

Multiferroic materials possessing both magnetic and ferroelectric order enable in principle to switch order parameters using not the direct reciprocal field, e.g. to switch the magnetization by an electric field or the electric polarization by a magnetic field. A recent breakthrough was achieved by the demonstration of the ferromagnetic switching of a Co layer with an electric field employing the multiferroic BiFeO 3 [1]. The latter material is a perovskite based oxide that shows stable ferro-electricity as well as an antiferromagnetic order at room temperature [2,3]. Due to a Dzyaloshinskii-Moriya interaction induced by rotation of oxygen octahedra leading to noncollinear Fe-O-Fe bonds a s…

Quantum paraelectric and induced ferroelectric states in

1996

Nominally pure has been studied by dielectric spectroscopy using small (linear regime) as well as large electrical fields (non-linear regime) up to . In addition measurements of the specific heat and its field-dependent contribution have been carried out. The field dependence of the dielectric constant and the specific heat can be well described by the transverse Ising Hamiltonian including tunnelling and external field terms. It gives evidence for the existence of polar clusters at low temperatures which are supposed to be associated with the quantum paraelectric state below in accord with recent free-energy calculations. The low-field third-harmonic susceptibility which measures the polar…

Effects of water dielectric saturation on the space–charge junction of a fixed-charge bipolar membrane

2000

Abstract The dielectric saturation at the space–charge junction of a fixed-charge bipolar membrane is studied using the theoretical approach by Booth for the water dielectric constant and the Poisson equation for the electrical double layer at the junction. The numerical solution gives the electric field and dielectric constant profiles through the junction as well as the junction thickness as a function of the voltage drop. The water dielectric constant decreases substantially for the large electric fields that may occur at the narrow bipolar junction.

Stark level crossing and optical-rf double resonance in NaK D 1 Π

1997

We report here (Lambda) -doubling splitting and permanent electric dipole moment d p measurements for a number of vibrotational levels of NaK D 1 II state. Two different methods, which are not Doppler limited, were used. Stark effect induced level crossing was registered as fluorescence polarization changes with external electric field, which allowed us to obtain, from one fit, the values of electric dipole moment and (Lambda) -doubling splitting (Delta) ef between e, f substates of an individual rotational state. Another method consisted in obtaining the ratio (Delta) ef /d p from electric field dependence of the intensity of forbidden line appeared in fluorescence as a result of e- f Star…

Electric Polarization of Onsager Fluids. II. Birefringence. 2. Molar Kerr Constants of Binary Solutions

1994

Electric polarization of Onsager fluids

2002

The problem of correct determination of electrical and optical characteristics of molecules of dielectric fluids can actually be brought to problem of description of the effective internal field which consist of the field included by external sources and the cumulate electric field of molecules on the medium including intermolecular interactions. An attempt was made to modify the model Onsager theory. A polarizable molecular dipole enclosed in spherical cavity is substituted for a rigid one submerged in polarizable medium which fills the cavity. The local dielectric permittivity of the Heaviside type is replaced for the oscillating, rapidly damping function of Fresnel integral. The analytic…

Comparison of the Influences of a Perpendicular and Parallel Uniaxial Stress on the Dielectric and Ferroelectric Properties of Fe Doped BaTiO3Ceramics

2014

The dielectric and ferroelectric properties of Fe-doped BaTiO3 ceramic under uniaxial stress applied perpendicular and parallel to the electric field are presented and analyzed. For the dielectric properties, the results showed that the uniaxial stress reduced an electric permittivity and dielectric losses for the both directions of applied stress. It was also found that an applied uniaxial pressure also enhanced a diffuse phase transformation behaviour. In the case of the ferroelectric properties the applied stress weakens a polarization when it is applied parallel (p∥ac) to the electric field. These results were interpreted through the stress induced domain switching process.

Evolution of dielectric properties in transparent PLZT 8.3/70/30 ceramics at the diffused phase transition

1999

Abstract The time evolution of dielectric properties after a temporary change of temperature and electric field is investigated. It is found, that below the temperature of ˛' maximum Tm the change of temperature and electric field creates an increase of dielectric permittivity followed by logarithmic decay when the change of these parameters is finished. At every temperature the dielectric properties are characterized by a unique ˛'(t) independent on previous thermal history. If the applied electric field is E< Ec, the state of polarization is not affected. The dependence on dielectric constant of storage time under field as well as field intensity is determined.