Field-induced giant static dielectric constant in nano-particle aggregates at room temperature

The analogy between magnetism and electricity was established by Maxwell in the 19th century, despite the subtle difference. While magnetic materials display paramagnetism, ferromagnetism, antiferromagnetism and diamagnetism, only paraelectricity, ferroelectricity and antiferrolelectricity have been found in dielectric materials. The missing ‘diaelectricity’ may be found if there exists a material that has a dc-polarization opposing the electric field or a negative dielectric susceptibility ?′???1, with ?′ being the real part of the relative dielectric constant. Both of these properties have been observed in nano-particle aggregates under a dc electric bias field at room temperature. A possible collective effect in the nano-particle aggregates is proposed to account for the observation. ‘Diaelectricity’ implies overscreening by polarization to the external charges. Materials with a negative static ?′ are expected to provide attraction to similar charges and unusual scattering to electromagnetic waves with possible profound implications for high temperature superconductivity and communications.     

Magnetoelectric multiferroicity and quantum paraelectricity in hexaferrites

Multiferroic materials with coexisting ferroelectric and magnetic orders have attracted tremendous research interests because of their intriguing fundamental physics as well as potential applications in the next-generation multifunctional devices. Hexaferrites with conical magnetic structures are among the most promising single-phase multiferroics because strong magnetoelectric effects can be achieved in them from low temperatures up to room temperature in low magnetic fields. In this review, after briefly introducing the background on multiferroics and classification of hexaferrites, we summarize recent progress in multiferroic hexaferrites, including the mechanisms of spin-induced ferroelectricity, the magnetoelectric phase diagram, giant direct and converse magnetoelectric effects. Furthermore, we present a new mechanism of magnetic-ion-induced displacive polarization in hexaferrites, which leads to quantum paraelectricity and quantum electric-dipole liquid in M-type hexaferrites.     

Influences of magnetic field on the coexistence of diquark and chiral condensates in the Nambu-Jona-Lasinio model with axial anomaly

In this paper, we study the influences of magnetic fields on the coexistence of diquark and chiral condensates in an extended Nambu–Jona–Lasinio model with QCD axial anomaly, as it relates to color-flavor-locked quark matter. Due to the coupling of rotated-charged quarks to magnetic fields, diquark condensates become split, and the coexistence region is thus superseded in favor of a specific diquark Bose–Einstein condensation (BEC), denoted as the BEC_I phase. For strong magnetic fields, we find that the BEC_I transition is pushed to larger quark chemical potentials. The effect of magnetic catalysis tends to disrupt the BEC–BCS (Bardeen–Cooper–Schrieffer) crossover predicted in previous works. For intermediate fields, the effect of inverse magnetic catalysis is observed, and the axial-anomaly-induced phase structure is essentially unchanged.     

Equation of State of the Strong Interaction Matter in an External Magnetic Field

We investigate the equation of state of the strong interaction matter in a background magnetic field via the two flavor Nambu-Jona-Lasinio model. Starting from the mean-field thermodynamical potential density Ω, we calculate the pressure density p, the entropy density s, the energy density ε, and the interaction measure (ε-3p)=T⁴ of the strong interaction matter at finite temperature and finite magnetic field. The results manifest that the chiral phase transition is just a crossover but not a low order phase transition. Moreover there may exist magnetic catalysis effect, and its mechanism is just the effective dimension reduction induced by the magnetic field.     

Hydrogen bonding in homochiral dimers of hydroxyesters studied by Raman optical activity spectroscopy

Spectroscopic analysis of homochiral dimerization is important for the understanding of the homochirality of life and enantioselective catalysis. In this paper, (S)‐methyl lactate and related molecules were studied to provide detailed structural information on hydrogen bonding in homochiral dimers of chiral α‐hydroxyesters through the experimental and theoretical study of Raman optical activity. Different homochiral dimers can be distinguished by comparing their simulated Raman optical activity spectra with the experimental results. Hydrogen bonding motions are decoded with the aid of vibrational motion analysis, which are apparently involved in vibrational motions below 800 cm^–1. A common feature related to the chain‐bending mode also indicates the absolute configuration of methyl lactate and related molecules. The differing behavior of electric dipole–electric quadrupole invariants (β(A)²) compared with the electric dipole–magnetic dipole invariant (β(G′)²), suggests that the intermolecular hydrogen bonding motion behaves differently from the intramolecular one in the asymmetric molecular electric and magnetic fields. These results may help understand hydrogen‐bonded self‐recognition and other dynamical features in chiral recognition. Copyright © 2011 John Wiley & Sons, Ltd.     

Chiral magnetic wave at finite baryon density and the electric quadrupole moment of the quark-gluon plasma

The chiral magnetic wave is a gapless collective excitation of quark-gluon plasma in the presence of an external magnetic field that stems from the interplay of chiral magnetic and chiral separation effects; it is composed of the waves of the electric and chiral charge densities coupled by the axial anomaly. We consider a chiral magnetic wave at finite baryon density and find that it induces the electric quadrupole moment of the quark-gluon plasma produced in heavy ion collisions: the "poles" of the produced fireball (pointing outside of the reaction plane) acquire additional positive electric charge, and the "equator" acquires additional negative charge. We point out that this electric quadrupole deformation lifts the degeneracy between the elliptic flows of positive and negative pions leading to v(2)(π(+))相似文献   

Waves in planar waveguide containing chiral nihility metamaterial

We investigate the guided waves in a three-layered planar waveguide, with one layer filled with air and the other two filled with the chiral nihility material. We have shown that no electric field exists in the chiral layers. However, the magnetic fields are nonzero within the chiral regions due to the decoupling between electric and magnetic fields. The disappearance of the electric field is caused by the negative reflections for two egienwaves in the chiral nihility at the boundaries of the planar waveguide. The electromagnetic energies can only be guided away from the source in the air layer. Simulation results have validated our theoretical analysis.     

Chiral magnetic effect in SU(2) lattice gluodynamics at zero temperature

The chiral magnetic effect is the appearance of a quark electric current along a magnetic-field direction in topologically nontrivial gauge fields. There is evidence that this effect is observed in collisions between heavy ions at the RHIC collider. The features of the chiral magnetic effect in SU(2) lattice gluodynamics at zero temperature have been investigated. It has been found that the electric current increases in the magnetic-field direction owing to quantum fluctuations of gluon fields. Fluctuations of the local charge density and chirality also increase with the magnetic field strength, which is a signature of the chiral magnetic effect.     

强磁场与涡旋场中的夸克胶子物质

相对论重离子碰撞可以产生高温的夸克胶子物质,同时也产生极强的电磁场和流体涡旋。在强电磁场和涡旋场中的夸克胶子物质呈现出新奇的宏观量子现象,比如手征磁效应、手征涡效应、手征分离效应、手征电分离效应、自旋极化现象等。它们一方面给我们提供了可以探测高温下量子色动力学的非平庸规范场拓扑结构、强相互作用的宇称破坏、夸克胶子物质中的自旋动力学等的实验手段,另一方面也与物理学其他分支,比如粒子物理、凝聚态物理、天体物理、冷原子物理等发生紧密联系,形成新的交叉研究领域。本文旨在对这些宏观量子现象的产生机制以及它们在相对论重离子碰撞中的探测等做一回顾和展望。特别地,我们揭示出重离子碰撞的磁场强度可以达到$10^{18}\sim 10^{20}$ G,流体涡旋可以达到$10^{22}$ s–1;这是我们已知当前宇宙中最强的磁场和流体涡旋。我们定量地对同量素碰撞实验做了分析,发现即便背景比例达到93%以上,当前的同量素碰撞实验仍然可在大约$3\sigma$的显著性水平上判断是否有手征磁效应的发生。我们系统地给出了满足因果律的自旋流体力学方程,并推导了其中的集体激发模式,这将有助于理解超子自旋极化中出现的符号问题。     

Crystalline electric field effects on the paramagnetic susceptibility of polycrystalline materials

The paramagnetic susceptibility of polycrystalline materials having large magnetic anisotropies is considered. It is shown that polycrystalline data in many case may not reflect strong crystalline electric field phenomena, even though these are clearly seen in single crystal data.     

The chiral magnetic effect and chiral symmetry breaking in <Emphasis Type="Italic">SU</Emphasis>(3) quenched lattice gauge theory

We study some properties of the non-Abelian vacuum induced by strong external magnetic field. We perform calculations in the quenched SU(3) lattice gauge theory with tadpole-improved Lüscher-Weisz action and chirally invariant lattice Dirac operator. The following results are obtained: The chiral symmetry breaking is enhanced by the magnetic field. The chiral condensate depends on the strength of the applied field as a power function with exponent ν = 1.6 ± 0.2. There is a paramagnetic polarization of the vacuum. The corresponding susceptibility and other magnetic properties are calculated and compared with the theoretical estimations. There are nonzero local fluctuations of the chirality and electromagnetic current, which grow with the magnetic field strength. These fluctuations can be a manifestation of the Chiral Magnetic Effect.     

Enhanced circular dichroism of plasmonic system in the strong coupling regime

The circular dichroism(CD) signal of a molecule is usually weak,however,a strong CD signal in optical spectrum is desirable because of its wide range of applications in biosensing,chiral photo detection,and chiral catalysis.In this work,we show that a strong chiral response can be obtained in a hybridized system consisting of an artificial chiral molecule and a nanorod in the strong coupling regime.The artificial chiral molecule is composed of six quantum dots in a helix assembly,and its CD signal arises from internal Coulomb interactions between quantum dots.The CD signal of the hybridized system is highly dependent on the Coulomb interactions and the strong coupling progress through the electromagnetic interactions.We use the coupled oscillator model to analyze strong coupling phenomenon and address that the strong coupling progress can amplify the CD signal.This work provides a scenario for designing new plasmonic nanostructures with a strong chiral optical response.     

Giant Asymmetric Transmission and Circular Dichroism with Angular Tunability in Chiral Terahertz Metamaterials

Inspired by the chiral structure from mode interaction, a chiral terahertz metamaterial and its complementary structure with the coexistence of asymmetric transmission and circular dichroism response are designed. The asymmetric transmission happens in the presence of electric and magnetic modes perpendicular to each other, resulting from intrinsic chirality under normal incidence. Circular dichroism exists in the presence of electric and magnetic modes parallel to each other under oblique incidence because of extrinsic chirality. Both asymmetric transmission and circular dichroism are enhanced by complementary structures, benefitting from the coupling between adjacent units. The maximum of chiral parameter κ can achieve 450, which is one hundred times higher than previously reported. The chiral response can be tuned by the incident angle and is sensitive to the environmental refractive index. The results highlight the potential applications of these metamaterials in chiral sensing and polarization transformation devices.     

Chirality Driven by Magnetic Dipole Response for Demultiplexing of Surface Waves

Surface electromagnetic waves are characterized by the intrinsic spin‐orbit interaction which results in the fascinating spin‐momentum locking. Therefore, directional coupling of light to surface waves can be achieved through chiral nanoantennas. Here, we show that dielectric nanoantenna provides chiral response with strong spectral dependence due to the interference of electric and magnetic dipole momenta when placed in the vicinity of the metal‐air interface. Remarkably, chiral behaviour in the proposed scheme does not require elliptical polarization of the pump beam or the geometric chirality of the nanoantenna. We show that the proposed ultracompact and simple dielectric nanoantenna allows for both directional launching of surface plasmon polaritons on a thin gold film and their demultiplexing with a high spectral resolution.     

SU(3) Polyakov Linear-Sigma Model: Magnetic Properties of QCD Matter in Thermal and Dense Medium

The linear-sigma model, in which information about confining gluons is included through the Polyakov-loop potential (PLSM), is considered in order to perform a systematic study for various magnetic properties of QCD matter under extreme conditions of high temperatures and densities and finite magnetic field strengths. The introduction of magnetic field to the PLSM Lagrangian requires suitable utilization of Landau quantization, modification in the dispersion relations, and momentum-space dimension-reduction. We observed that increasing the magnetic field leads to filling-up lower Landau levels first and decreasing the number of occupied levels. We conclude that the population of Landau levels is most sensitive to the magnetic field and to the quark charges. The influences of finite magnetic field on the temperature dependence of chiral and deconfinement order-parameter(s) are studied. We present estimations for the magnetization, the magnetic susceptibility, the permeability, and the catalytic properties of QCD matter as functions of temperature. The dependences of the resulting freeze-out parameters, temperatures, and baryon chemical potentials on the corresponding magnetic field strengths have been analyzed, as well. These calculations are compared with recent lattice QCD simulations, whenever available. We conclude that the QCD matter seems to have paramagnetic property at temperatures greater than the critical one. There is an evidence for weak diamagnetic property at low temperatures. Last but not least, we observe that the magnetic catalysis is inverse, namely, the critical temperatures decrease with increasing the magnetic field.     

The role of Debye mass in the chiral crossover in a strong magnetic field

In this paper, the Debye mass of quarks is investigated in the Nambu–Jona-Lasinio model at zero and nonzero chemical potentials. In a uniform plasma, the Debye mass usually behaves as a monotonous increasing function of the temperature, the chemical potential and the magnetic field. At the fixed coupling interaction G, we find that the magnetic catalysis (MC) on the occurrence of the chiral restoration could be revealed by the susceptibility of the Debye mass dm_D/dT at low chemical potential and by the quantity Tdm_D/dT in the region of moderate densities. However, the inverse MC is realized under a thermomagnetic coupling constant G(B, T) by the behavior of the Debye mass at both zero and nonzero chemical potentials.     

Paramagnetic magnetochiral effect in the H h and V h components of Rayleigh light scattering by molecular systems

A static magnetic field, acting on an isotropic medium composed of paramagnetic chiral molecules perpendicular to the propagation direction of the optical beam, is shown to induce an axial differential effect—magnetochiral Rayleigh light scattering. Diamagnetic and paramagnetic contributions to the effect are given in terms of the linear and nonlinear electric dipole, magnetic dipole and electric quadrupole polarizabilities responsible also for natural optical activity, the Faraday effect as well as magnetochiral birefringence. Specific cases are discussed.     

Magnetoelectric properties in A-type antiferromagnet in an electric field

Mean-field theory based on Heisenberg model is used to investigate the magnetic and magnetoelectric properties at a finite temperature in the A-type antiferromagnetic lattice, in which we consider that an applied electric field can generate a bulk magnetic moment. We have calculated the magnetic moment, magnetic susceptibility and magnetoelectric susceptibility as a function of temperature for A-type antiferromagnetic system. It is demonstrated that an applied electric field together with the coupling parameter has an effect on the magnetic ordering behavior. Our results are almost consistent with those of spin-wave theory within the range of low temperature.     

Chiral electric field in relativistic heavy-ion collisions at energies available at the BNL Relativistic Heavy Ion Collider and at the CERN Large Hadron Collider

It has been proposed that electric fields may lead to chiral separation in quark-gluon plasma(QGP).This is called the chiral electric separation effect.The strong electromagnetic field and the QCD vacuum can both be completely produced in off-central nuclear-nuclear collision.We use the Woods-Saxon nucleon distribution to calculate the electric field distributions of off-central collisions.The chiral electric field spatial distribution at Relativistic Heavy-Ion Collider(RHIC) and Large Hadron Collider(LHC) energy regions are systematically studied in this paper.The dependence of the electric field produced by the thermal quark in the central position with different impact parameters on the proper time with different collision energies in the RHIC and LHC energy regions are studied in this paper.