Influence Of Domain Structure Research Articles

Influence of Domain Structure in Ferroelectric Substrate on Graphene Conductance (Authors' Review)

Review is devoted to the recent theoretical studies of the impact of domain structure of ferroelectric substrate on graphene conductance. An analytical description of the hysteresis memory effect in a field effect transistor based on graphene-on-ferroelectric, taking into account absorbed dipole layers on the free surface of graphene and localized states on its interfaces is considered. The aspects of the recently developed theory of p-n junctions conductivity in a graphene channel on a ferroelectric substrate, which are created by a 180-degree ferroelectric domain structure, are analyzed, and cases of different current regimes from ballistic to diffusion one are considered. The influence of size effects in such systems and the possibility of using the results for improving the characteristics of field effect transistors with a graphene channel, non-volatile ferroelectric memory cells with random access, sensors, as well as for miniaturization of various devices of functional nanoelectronics are discussed.

The influence of domain structures and phase transition on transmittance of PZN–PT ferroelectric crystal

A 0.93Pb(Zn1/3Nb2/3)O3–0.07PbTiO3(PZN–PT) single crystal was grown using the flux Bridgman method and 〈0 0 1〉-oriented slides were obtained. Strip-shaped and needle-shaped domains were observed in the same PZN–PT sample by a polarizing microscope. Raman spectra and transmittance spectra of regions with different domain structures have been measured. The Raman spectra exhibit slight differences in order information in different domain regions. The transmittance of strip-shaped domain regions is higher than that of needle-shaped domain regions, which means that the domain structures play a role in optical inhomogeneity. The temperature dependence of the domains and transmittance spectra has been investigated by in situ observation. The results show that the transmittance was influenced significantly by the ferroelectric phase transition, including the domain structure.

Temperature dependence of dielectric and electromechanical properties of (K,Na)(Nb,Ta)O3 single crystal and corresponding domain structure evolution.

Domain structures and their evolution with temperature in the [001] C oriented (K,Na)(Nb,Ta)O3 (KNNT) single crystal have been studied before and after poling by polarizing light microscopy. The results indicate that the KNNT crystal is difficult to be completely poled by the room temperature poling process. The domain structure is rather stable in the orthorhombic phase, but exhibits substantial changes near the phase transition temperatures TO-T and TC. Narrower stripe domains are formed during both the orthorhombic-tetragonal and tetragonal-cubic phase transition processes, no intermediate phases were found during the phase transitions. The temperature dependence of the dielectric and piezoelectric properties were measured, and the influence of domain structures on the dielectric and electromechanical properties were quantified.

The Influence of Domain Structure on the Faraday Effect in Terbium Garnet Ferrite in the Vicinity of the Magnetic-Compensation Temperature

The temperature dependence of the Faraday effect in terbium garnet ferrite, Tb3Fe5O12, is investigated near its magnetic-compensation temperature, Т с = 249 K. A non-monotonous variation in the value of the Faraday rotation angle Ф is observed in a weak magnetic field as the temperature approaches Т с : the temperature plot of the Faraday rotation angle has two local maxima observed left and right of the magnetic compensation point. A theoretical model is proposed, which follows from the phenomenological theory of domain-boundary displacement under the action of a magnetic field, offering an unambiguous description of the principles of domain-structure influence on the Faraday effect in Tb3Fe5O12 near Т с .

Influence of domain structure on the nonlinear polarization properties of A 2 BX 4-group crystals

Harmonic analysis of repolarization in A 2 BX 4-group crystals in the ferroelectric phase near phase-transition temperature T c is used to separate the contributions to the harmonic-component amplitudes in the output signal of a Sawyer-Tower circuit from charging the reference capacitor with capacitive and conductive current through such a crystal. Harmonic analysis of dielectric hysteresis loops obtained by placing a specimen in an electric field with harmonically changing strength reveals general regularities in the evolution of the domain walls of A 2 BX 4-group crystals. It is established that the domain structure affects the nonlinear polarization properties of our specimens. The dependence of the potential relief of ferroelectric ion motion in a harmonically changing electric field is plotted on the basis of the experimental results.

The Influence of Domain Structures on the Signal Transduction of Chimeric Receptors Derived from the Erythropoietin Receptor

Although cytokine receptors regulate many cellular functions, contribution of receptor's domains and their conformation to signal transduction remains unclear. In this study, we designed a series of chimeric erythropoietin receptor (EpoR) variants encoding a haemagglutinin epitope-tagged anti-fluorescein single-chain Fv and different combinations of extracellular D1/D2 domain(s) of EpoR as the extracellular domain to allow the receptor to be activated by multiple ligands. Furthermore, one to four Ala residues were inserted at the intracellular juxtamembrane region of each chimeric receptor to modulate the conformation of the intracellular domain. When the chimeric receptors were expressed in Ba/F3 cells, cell-surface expression levels of chimeric receptors without D2 domain were markedly lowered, suggesting a role of D2 domain for stabilizing the receptor. Furthermore, the ligand-dependent cell proliferation was strongly affected by extracellular domain structures and the number of inserted Ala residues. Moreover, the conformational change of chimeric receptors was induced by various ligands to detect the phosphorylation of JAK2, STAT5 and ERK2, whose activations are characteristics of EpoR signalling. Consequently, the phosphorylation pattern of these signal transducers was significantly influenced by ligands and receptor variants. These results indicate that signal transduction of EpoR is strongly affected by conformation of both extracellular and intracellular domains.

Material properties and domain structure influence on pole erasure occurrence in perpendicular recording heads

The influence of the material properties and the domain structure of the yoke on pole erasure was investigated. A writer pole material with high anisotropy field (H/sub k/) can suppress pole erasure because it can create a 180/spl deg/ domain wall parallel to the head transverse direction. One of the causes of the pole erasure is due to the induced magnetic anisotropy in the pole tip region by the magnetoelastic effect.

Effect of phase transition on the surface potential of the BaTiO3 (100) surface by variable temperature scanning surface potential microscopy

Variable temperature atomic force microscopy and scanning surface potential microscopy are used to characterize the ferroelectric BaTiO3 (100) surface. The influence of domain structure on surface topography and surface potential distribution is discussed. Domain induced surface corrugations were found to disappear above the Curie temperature confirming the local phase transition. Associated variations of surface potential are quantified. Relaxation of surface potential after the transition to paraelectric state on heating and during the transition to the ferroelectric state on cooling was observed. Differences in kinetics of the topographic structure and surface potential variations are used to distinguish polarization compensation mechanisms.

Influence of domain structure on the electromechanical properties of lead zirconate-titanate and metal/sodium-bismuth titanate ferroelectric ceramics

Influence of domain structure on the electromechanical properties of lead zirconate-titanate and metal/sodium-bismuth titanate ferroelectric ceramics

Two-domain model of magnetization in thin discs with uniaxial magnetic anisotropy

The domain structure influence upon the magnetization processes in thin magnetic discs with uniaxial anisotropy is discussed. The critical magnetic fields of transformation from multidomain to one-domain structure in the sample are calculated. The theoretical dependences are verified experimentally by torque moment measurements.

Ferroelasticity and superconductivity of YBa2Cu3O7−δceramics

Abstract YBa2Cu3O7−δ ceramic samples are found to show ferroelastic domain switching in the temperature range from 85 K to 925 K. The influence of domain structure on the elastic and anelastic properties and the temperature of the phase transition into the superconducting phase has been observed.

Sequestering and the influence of domain structure on excimer formation in spread monolayers

Etude appliquee a l'acide pyrene-1 dodecanoique-12 dans une solution d'acide oleique. Influence de l'excitation sur l'efficacite de formation de l'excimere

Influence of domain structure on photoluminescence of lead magnoniobate (pmn)

Abstract In this paper we report studies of photoluminescence in the ferroelectric with diffuse transition and its relationship to the phase transition. The spectral and temperature dependence of photoluminescence showed that luminescence spectra of Pb3MgNb2O5 is of the admixture type. In the region of the ferroelectric phase transition of Pb3MgNb2O9 an anomaly in photoluminescence is observed. It is shown that this anomaly is correlated with the domain structure. The results are interpreted by resorting to a model of autolocalized “phason” states of the carrier in the region of the ferroelectric phase transition.

Influence of domain structure on some dynamic properties of ferromagnets

A review is presented of theoretical investigations into the influence of domain structure and dynamic behaviour of domain walls on some low- and high-frequency properties of ferromagnetic materials, The effect of dynamic bowing of domain walls on electromagnetic losses in electrical steel is analyzed in detail. The theories of Pry, Bean and Bishop are generalized to explain experimentally observed nonlinear dependence of eddy-current power losses on frequency and wall spacing. A study is made of the influence of domain structure on the parametric excitation of spin waves with account being taken of domain wall structure. It is shown that the lowest parametric excitation threshold corresponds to spin waves within domain walls and that the parametric excitation effect is rather sensitive to domain wall structure. The influence of a characteristic domain structure arising on the basis of a twinning structure of magnetically ordering alloys on the Mössbauer spectra is analyzed. It is shown that the observed special features of these spectra may be explained on the basis of this domain structure.

The influence of domain structure on the magnetic properties of hematite

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The Influence of Domain Structure on the Magnetization Curves of Single Crystals

It is pointed out that the lack of agreement between theoretical and experimental magnetization curves found for single crystals in low fields is probably caused, not by residual internal strains, but by neglect of the domain structure of the crystal in the theoretical calculations. Using Neel's model for the domain structure of a single crystal of iron in the form of a strip parallel to the [110] direction, magnetization curves have been calculated taking the domain structure into proper account. It is found that the (I, H) curves depend explicitly on the width of the crystal. Comparison is made between the calculated curves and the experimental results of Williams. The agreement between the two is good.