Hasil untuk "Electric apparatus and materials. Electric circuits. Electric networks"

Himakshi Mishra, Surbhi Slathia, Bruno Ipaves et al.

Controlling the alignment of two dimensional (2D) materials is crucial for optimizing their electronic and mechanical properties in next generation devices. This study explores how electric fields can manipulate the orientation of 2D diopside (CaMgSi2O6) flakes, a flexible silicate material, through a phenomenon called flexoelectricity, where applied voltage generates mechanical strain. We exfoliated diopside crystals into ultrathin flakes, placed them on microelectrodes, and used AC electric fields to induce alignment via acoustic strain. Raman spectroscopy showed that the flakes reoriented/realigned under the field, with vibrational peaks weakening most at high frequencies (10 MHz). Electrical tests revealed this alignment improves conductivity by 20-30%, as straightened flakes create better pathways for current flow. Fully atomistic molecular dynamics simulations further explained how these flakes naturally align on surfaces within picoseconds, matching our experimental observations. Together, these findings demonstrate a practical way to tune diopside properties using electric fields, opening doors for its use in flexible electronics, sensors, and energy devices.

Jiangxu Huang, Hanqing Li, Jiaqi Che et al.

Electrofreezing is a powerful technique that employs the electric field to control and enhance the freezing process. In this work, a phase-field-based lattice Boltzmann (LB) method is developed to study the electrofreezing process of sessile droplet on a cooled substrate. The accuracy of the present LB method is first validated through performing some simulations of the three-phase Stefan problem, the droplet freezing on a cold wall, and the droplet deformation under a uniform electric field. Then it is used to investigate the effect of an electric field on the freezing of a wetting droplet on a cold substrate, and the numerical results show that the electric field has a significant influence on the freezing time of the droplet mainly through changing the morphology of the droplet. In particular, under the effect of the electric field, the freezing time is increased for the droplet with a prolate pattern, while the freezing time of the droplet with an oblate pattern is decreased. These numerical results bring some new insights on the electrofreezing and provide a valuable guidance for the precise regulation of droplet freezing.

Akane Inda, Satoru Hayami

An electric toroidal dipole (ETD) moment is one of the fundamental dipole moments as well as electric and magnetic ones. Although it directly couples to neither an electric nor magnetic field due to its spatial inversion and time-reversal parities, its ordered state leads to unconventional transverse responses of the conjugate physical quantities. We here theoretically investigate nonlinear transverse magnetic susceptibility under the ETD ordering. By performing a self-consistent mean-field calculation for a five $d$-orbital model under a tetragonal crystalline electric field and using the nonlinear Kubo formula, we show that a third-order transverse magnetic susceptibility corresponding to a uniform magnetization perpendicular to the external magnetic field becomes nonzero once the ETD moment is ordered under tetragonal crystalline electric field. Moreover, we find that spin-orbital entanglement and a low-lying first excited crystal-field level are important for realizing large transverse responses.

Gowthama K K, Manu Kurian, Vinod Chandra

The electric charge transport in a weakly magnetized hot QCD medium has been investigated in the presence of an external inhomogeneous electric field. The current densities (electric and Hall)induced by the inhomogeneous electric field have been estimated in the regime where space-time inhomogeneity of the field is small so that the collisional effect in the medium cannot be neglected. The collisional aspect of the medium has been captured by employing both relaxation time approximation and Bhatnagar-Gross-Krook collision kernel in the relativistic Boltzmann equation. The magnetic field, momentum anisotropy, and quark chemical potential dependences of the electric current and Hall current densities have been explored, and the impacts on the respective conductivities have been studied. The inhomogeneities of the field are seen to have sizable effects on the electromagnetic responses of the collisional medium.

Xi-Bin Li

This work is a supplement on the previous research about primordial electromagnetic fields. In this work, three important problems are discussed: the evolution of primordial electric fields, the electric and particle densities' solitons in plasma before recombination and their influences on the power spectra of cosmic microwave background. Detailed computations show that the primordial electric fields dissipate by Landau damping effect on both large scale and small scale and there is no impact on the spectrum. While, before recombination, there exist solitary waves stably propagating in plasma whose speed is significantly slower than that of baryonic acoustic oscillations, working only at extremely small scale. On the other hand, the amplitude of solitons is so weak that only a significantly small contribution on the phase of baryon acoustic oscillations, so there merely exist the messages about such electric solitary waves on the spectrum. In a word, as relevant monographs on cosmology, neglecting the electromagnetic fields (electric fields at least) is a reasonable treatment on the calculations of cosmic microwave background. However, the protonic density fluctuations show a form of KdV equation while its propagation as a stable solitary wave, leading a probability to the origin of fluctuation promoting the generation and evolution of galaxies.

Yue Li, Chen Chen, Wei Li et al.

Tuning the electric properties of crystalline solids is at the heart of material science and electronics. Generating the electric field-effect via an external voltage is a clean, continuous and systematic method. Here, utilizing the unique electric dipole locking in van der Waals (vdW) ferroelectric alpha-In2Se3, we report a new approach to establish the electric gating effect, where the electrostatic doping in the out-of-plane direction is induced and controlled by an in-plane voltage. With the vertical vdW heterostructure of ultrathin alpha-In2Se3 and MoS2, we validate an in-plane voltage gated coplanar field-effect transistor (CP-FET) with distinguished and retentive on/off ratio. Our results demonstrate unprecedented electric control of ferroelectricity, which paves the way for integrating two-dimensional (2D) ferroelectric into novel nanoelectronic devices with broad applications.

Alessandro Arduino, Oriano Bottauscio, Mario Chiampi et al.

Uncertainty propagation in a phaseless magnetic resonance-based electric properties tomography technique is investigated using the Monte Carlo method. The studied inverse method, which recovers the electric properties distribution at radiofrequency inside a scatterer irradiated by the coils of a magnetic resonance imaging scanner, is based on the contrast source inversion technique adapted to process phaseless input data.

Xu-Lin Zhang, S. B. Wang, Zhifang Lin et al.

We study the optical forces acting on toroidal nanostructures. A great enhancement of optical force is unambiguously identified as originating from the toroidal dipole resonance based on the source-representation, where the distribution of the induced charges and currents is characterized by the three families of electric, magnetic, and toroidal multipoles. On the other hand, the resonant optical force can also be completely attributed to an electric dipole resonance in the alternative field-representation, where the electromagnetic fields in the source-free region are expressed by two sets of electric and magnetic multipole fields based on symmetry. The confusion is resolved by conceptually introducing the irreducible electric dipole, toroidal dipole, and renormalized electric dipole. We demonstrate that the optical force is a powerful tool to identify toroidal response even when its scattering intensity is dwarfed by the conventional electric and magnetic multipoles.

Gaoqing Cao, Xu-Guang Huang

We systematically study the chiral symmetry breaking and restoration in the presence of a pure electric field in the Nambu--Jona-Lasinio (NJL) model at finite temperature and baryon chemical potential. In addition, we also study the effect of the chiral phase transition on the charged pair production due to the Schwinger mechanism. For these purposes, a general formalism for parallel electric and magnetic fields is developed at finite temperature and chemical potential for the first time. In the pure electric field limit $B\rightarrow0$, we compute the order parameter, the transverse-to-longitudinal ratio of the Goldstone mode velocities, and the Schwinger pair production rate as functions of the electric field. The inverse catalysis effect of the electric field to chiral symmetry breaking is recovered. And the Goldstone mode is find to disperse anisotropically such that the transverse velocity is always smaller than the longitudinal one, especially at nonzero temperature and baryon chemical potential. As expected, the quark-pair production rate is greatly enhanced by the chiral symmetry restoration.

Xiaohui Liu, J. D. Burton, Evgeny Y. Tsymbal

Electric-field control of spin-dependent properties has become one of the most attractive phenomena in modern materials research due the promise of new device functionalities. One of the paradigms in this approach is to electrically toggle the spin polarization of carriers injected into a semiconductor using ferroelectric polarization as a control parameter. Using first-principles density functional calculations, we explore the effect of ferroelectric polarization of electron-doped BaTiO3 (n-BaTiO3) on the spin-polarized transmission across the SrRuO3/n-BaTiO3 (001) interface. Our study reveals that the interface transmission is negatively spin-polarized and that ferroelectric polarization reversal leads to a change in the transport spin polarization from -65% to -98%. We show that this effect stems from the large difference in Fermi wave vectors between up- and down-spins in ferromagnetic SrRuO3 and a change in the transport regime driven by ferroelectric polarization switching. The predicted sizeable change in the spin polarization provides a non-volatile mechanism to electrically control spin injection in semiconductor-based spintronics devices.

F. S. Mozer, C. H. K. Chen

By searching through more than 10 satellite-years of THEMIS and Cluster data, three reliable examples of parallel electric field turbulence in the undisturbed solar wind have been found. The perpendicular and parallel electric field spectra in these examples have similar shapes and amplitudes, even at large scales (frequencies below the ion gyroscale) where Alfvenic turbulence with no parallel electric field component is thought to dominate. The spectra of the parallel electric field fluctuations are power laws with exponents near -5/3 below the ion scales (~ 0.1 Hz), and with a flattening of the spectrum in the vicinity of this frequency. At small scales (above a few Hz), the spectra are steeper than -5/3 with values in the range of -2.1 to -2.8. These steeper slopes are consistent with expectations for kinetic Alfven turbulence, although their amplitude relative to the perpendicular fluctuations is larger than expected.

Hong-Bo Chen, Ye-Hua Liu, You-Quan Li

The dynamics of a multiferroic domain wall in which an electric field can couple to the magnetization via inhomogeneous magnetoelectric interaction is investigated by the collective-coordinate framework. We show how the electric field is capable of delaying the onset of the Walker breakdown of the domain wall motion, leading to a significant enhancement of the maximum wall velocity. Moreover, we show that in the stationary regime the chirality of the domain wall can be efficiently reversed when the electric field is applied along the direction of the magnetic field. These characteristics suggest that the multiferroic domain wall may provide a new prospective means to design faster and low-power-consumption domain wall devices.

Camille Aron, Gabriel Kotliar, Cedric Weber

We study the steady-state dynamics of the Hubbard model driven out-of-equilibrium by a constant electric field and coupled to a dissipative heat bath. For very strong field, we find a dimensional reduction: the system behaves as an equilibrium Hubbard model in lower dimensions. We derive steady-state equations for the dynamical mean field theory in the presence of dissipation. We discuss how the electric field induced dimensional crossover affects the momentum resolved and integrated spectral functions, the energy distribution function, as well as the steady current in the non-linear regime.

Yu Tian, Minliang Zhang, Jile Jiang et al.

Shear thickening is a phenomenon of significant viscosity increase of colloidal suspensions. While electrorheological (ER) fluids can be turned into a solid-like material by applying an electric field, their shear strength is widely represented by the attractive electrostatic interaction between ER particles. By shearing ER fluids between two concentric cylinders, we show a reversible shear thickening of ER fluids above a low critical shear rate (<1 s-1) and a high critical electric field strength (>100 V/mm), which could be characterized by a modified Mason number. Shear thickening and electrostatic particle interaction-induced inter-particle friction forces is considered to be the real origin of the high shear strength of ER fluids, while the applied electric field controls the extent of shear thickening. The electric field-controlled reversible shear thickening has implications for high-performance ER/magnetorheological (MR) fluid design, clutch fluids with high friction forces triggered by applying local electric field, other field-responsive materials and intelligent systems.

Chris Ford

The possibility that QED and recently developed non-Hermitian, or magnetic, versions of QED are equivalent is considered. Under this duality the Hamiltonians and anomalous axial currents of the two theories are identified. A consequence of such a duality is that particles described by QED carry magnetic as well as electric charges. The proposal requires a vanishing zero bare fermion mass in both theories; Dirac mass terms are incompatible with the conservation of magnetic charge much as Majorana masses spoil the conservation of electric charge. The physical spectrum comprises photons and massless spin-1/2 particles carrying equal or opposite electric and magnetic charges. The four particle states described by the Dirac fermion correspond to the four possible charge assignments of elementary dyons. This scale invariant spectrum indicates that the quantum field theory is finite. The Johnson Baker Willey eigenvalue equation for the fine structure constant in finite spinor QED is interpreted as a Dirac-like charge quantisation condition for dyons.

S. N. Andreev, V. P. Makarov, V. I. Tikhonov et al.

Stark effect is calculated by the perturbation theory method separately for the ortho and para water molecules. At room temperature, a 30%-difference in the energy change is found for the two species put in electric field. This implies a sorting of the ortho and para water molecules in non-uniform electric fields. The ortho/para water separation is suggested to occur in the course of steam sorption on a solid surface and of large-scale atmospheric processes.

Giovanni Fanchini, Husnu Emrah Unalan, Manish Chhowalla

We report on electrical Raman measurements in transparent and conducting single-wall carbon nanotube (SWNT) thin films. Application of external electric field results in downshifts of the D and G modes and in reduction of their intensity. The intensities of the radial breathing modes increase with electric field in metallic SWNTs, while decreasing in semiconducting SWNTs. A model explaining the phenomenon in terms of both direct and indirect (Joule heating) effects of the field is proposed. Our work rules out the elimination of large amounts of metallic SWNTs in thin film transistors using high field pulses. Our results support the existence of Kohn anomalies in the Raman-active optical branches of metallic graphitic materials [Phys. Rev. Lett. 93 (2004) 185503].

Mario Castro, Francisco Dominguez-Adame

We present a throughout study of transmission and localization properties of Fibonacci superlattices, both in flat band conditions and subject to homogeneous electric fields perpendicular to the layers. We use the transfer matrix formalism to determine the transmission coefficient and the degree of localization of the electronic states. We find that the fragmentation pattern of the electronic spectrum is strongly modified when the electric field is switched on, this effect being more noticeable as the system length increases. We relate those phenomena to field-induced localization of carriers in Fibonacci superlattices.

Alejandro Corichi, Kirill Krasnov

We consider the loop quantization of Maxwell theory. A quantization of this type leads to a quantum theory in which the fundamental excitations are loop-like rather than particle-like. Each such loop plays the role of a quantized Faraday's line of electric flux. We find that the quantization depends on an arbitrary choice of a parameter e that carries the dimension of electric charge. For each value of e an electric charge that can be contained inside a bounded spatial region is automatically quantized in units of hbar/4*pi*e. The requirement of consistency with the quantization of electric charge observed in our Universe fixes a value of the, so far arbitrary, parameter e of the theory. Finally, we compare the ambiguity in the choice of parameter e with the beta-ambiguity that, as pointed by Immirzi, arises in the loop quantization of general relativity, and comment on a possible way this ambiguity can be fixed.

T. Zhao, S. R. Shinde, S. B. Ogale et al.

An external electric field induced reversible modulation of room temperature magnetic moment is achieved in an epitaxial and insulating thin film of dilutely cobalt-doped anatase TiO2. This first demonstration of electric field effect in any oxide based diluted ferromagnet is realized in a high quality epitaxial heterostructure of PbZr0.2Ti0.8O3/Co:TiO2/SrRuO3 grown on (001) LaAlO3. The observed effect, which is about 15% in strength in a given heterostructure, can be modulated over several cycles. Possible mechanisms for electric field induced modulation of insulating ferromagnetism are discussed.