Asymmetric scattering behaviors of spin wave dependent on magnetic vortex chirality

We investigate asymmetric spin wave scattering behaviors caused by vortex chirality in a cross-shaped ferromagnetic system by using the micromagnetic simulations.In the system,four scattering behaviors are found:(i)asymmetric skew scattering,depending on the polarity of vortex core,(ii)back scattering(reflection),depending on the vortex core stiffness,(iii)side deflection scattering,depending on structural symmetry of the vortex circulation,and(iv)geometrical scattering,depending on waveguide structure.The first and second scattering behaviors are attributed to nonlinear topological magnon spin Hall effect related to magnon spin-transfer torque effect,which has value for magnonic exploration and application.

Optical chirality induced by spin–orbit interaction of light in a tightly focused Laguerre–Gaussian beam

Optical chirality is one of the important and fundamental dynamic properties of light besides energy, momentum,and angular momentum. The quantification of electromagnetic chirality has been conceptualized only recently. Now, it is well known that for paraxial plane waves of light, the optical chirality is proportional to the ellipticity of the polarization ellipse, i.e., completely independent of the phase distribution. Here it is shown that optical vortex and state of polarization of the source paraxial field both have contributions to the optical chirality of the nonparaxial field generated by tightly focused Laguerre–Gaussian(LG) beam, which is in Stark contrast to the paraxial plane wave of light known from classical optics. The physical reason is the redistribution of local electromagnetic polarization in three dimensions associated with spin–orbit interaction.

MoiréMetasurface with Triple-Band Near-Perfect Chirality

Chiral metasurfaces have been proven to possess great potential in chiroptical applications.However,the multiband chiral metasurface with near-perfect circular dichroism has not been well studied.Also,the widely used bilayer metasurface usually suffers from the interlayer alignment and weak resonance.Here,we propose a twisted Moirémetasurface which can support three chiral bands with near-unity circular dichroism.The Moirémetasurface can remove the restriction of interlayer alignment,while maintaining a strong monolayer resonance.The two chiral bands in the forward direction can be described by two coupled-oscillator models.The third chiral band is achieved by tuning the interlayer chiral mode on resonance with the intralayer mode,to eliminate the parallel and converted components simultaneously.Finally,we study the robustness and tunability of the triple-layer Moirémetasurface in momentum space.This work provides a universal method to achieve three near-unity circular dichroism bands in one metasurface,which can promote applications of chiral metasurfaces in multiband optical communication,chiral drug separation,sensing,optical encryption,chiral laser,nonlinear and quantum optics,etc.

Phylogenetic Analysis of Chirality of Twining Plants

Phylogenetic relations of twining chirality of Dioscorea sp.in China were analyzed based on the genes matK,rbcL and trnL;phylogenetic character of higher-level phylogeny of twining plants was analyzed at a high taxon level based on matK gene.A significant phylogenetic framework of chirality was found:(i)based on matK analysis,right-handed Dioscorea species in China congregate completely to form a monophyly;(ii)rbcL and trnL data sets also supported Chinese right-handed Dioscorea a monophyly,although with ex...

Electromagnetic chirality-induced negative refraction with the same amplitude and anti-phase of the two chirality coefficients

This paper suggests a scheme of electromagnetic chirality-induced negative refraction utilizing magneto-lectric cross coupling in a four-level atomic system. The negative refraction can be achieved with the two chirality coefficients having the same amplitude but the opposite phase, without requiring the simultaneous presence of an electric-dipole and a magnetic-dipole transition near the same transition frequency.

Molecular Chirality and Chiral Superlattice in Crystal of Tetrakis[(pyrrol-1-yl)methyl]methane

The crystal structure of tetrakis[(pyrrol-1-yl)methyl]methane was determined by X-ray diffraction measurement, and the result shows that it belongs to monoclinic crystal system, space group is P2 1/n, with a=0.9284(3) nm, b=1.0950(6) nm, c=1.8749(8) nm; α=γ= 90.00(4)°, β=103.63(3)°, V=1.8523(14) nm 3, Z=4, ρ calcd. =1.192 kg/m 3, μ=0.072 nm -1 , F(000)=712, R 1=0.0854, wR 2=0.1884. It has been found that the molecules exist in two enantiomeric states. Enantioselective self-assemblies such as one-dimensional molecular stacks in a single handedness, homochiral monolayers and a chiral superlattice are specified in this racemic crystal. In addition, a simple technique is advocated to distinguish chiral states from tetrahedral molecules in the solid state. The present R/S nomenclature of the tetracooradinated carbon centers is used solely for its convenience to distinguish the two enantiomeric states, but not used to determine the absolute configurations.

Analytical solutions for elastic binary nanotubes of arbitrary chirality

Analytical solutions for the elastic properties of a variety of binary nanotubes with arbitrary chirality are obtained through the study of systematic molecular mechanics. This molecular mechanics model is first extended to chiral binary nanotubes by introducing an additional out-of-plane inversion term into the so-called stick-spiral model, which results from the polar bonds and the buckling of binary graphitic crystals. The closed-form expressions for the longitudinal and circumferential Young's modulus and Poisson's ratio of chiral binary nanotubes are derived as functions of the tube diameter. The obtained inversion force constants are negative for all types of binary nanotubes, and the predicted tube stiffness is lower than that by the former stick-spiral model without consideration of the inversion term, reflecting the softening effect of the buckling on the elastic properties of binary nanotubes. The obtained properties are shown to be comparable to available density functional theory calculated results and to be chirality and size sensitive. The developed model and explicit solutions provide a systematic understanding of the mechanical performance of binary nanotubes consisting of III-V and II-VI group elements.

C_3-Symmetric Molecules with Axial Chirality and Handed Arrangement of Dipole Fields

Introduction Chirality is defined as the absence of inversion symmetry,however,it is actually a pseudo-scalar of objects or figures,and does not depend for its definition on any connection to the physical world[1-5]. Logically,chiral molecules may possess other inherent physical quantity that guarantees the connection to the physical world[6,7].

Quest for Chirality in ^(107)Ag

High spin states in 107Ag have been studied via the 100Mo （11B, 4n） 107Ag reaction at a beam energy of 60 MeV on the HI-13 tandem accelerator at the China Institute of Atomic Energy. By analyzing the gamma-gamma coincidence and their DCO ratios, a new level scheme of 107Ag is presented. The structures for the newly constructed bands are briefly discussed and tentatively assigned to be chiral doublet bands.

Chirality pairing recognition,a unique reaction forming spiral alkaloids from amino acids stereoselectively in one-pot

A novel chirality pairing recognition was found between D-and L-amino acid derivatives.Novel spiral alkaloids formed in the recognition reaction.Possible mechanism was proposed for the stereoselective and chemoselective reactions.

Magnetoelectrochemical Chirality in Ag E lectrod e position

Chiral behaviors of magnetoelectrodeposited Ag film electrodes were investigated for the electrochemical reactions of glucose and cysteine. The Ag films were electrodeposited under a magnetic field of 2 T perpendicular to the electrode surface at various potentials 0f-0.06-0.4 V （vs Ag I Ag＋）. The current-time curves during the electrodeposition and the surface morphology of the films implied that the film growth was considerably affected by the micro-MHD （magnetohydrodynamic） effect. Such Ag films were employed as an electrode, and voltammograms of glucose and cysteine were examined. Chiral behavior was clearly observed as current difference between the enantiomers on the film electrodes prepared at electrodeposition potentials less than -0.1 V. Such electrochemical chirality disappeared after the oxidation and reduction of the surface monolayer, and this fact indicates that the chiral sites must be just on the film surface.

Effect of Chirality on the Electronic Transport Properties of the Thioxanthene-Based Molecular Switch

Based on the nonequilibrium Green function method and density functional theory calculations, we theoretically investigate the effect of chirality on the electronic transport properties of thioxanthene-based molecular switch. The molecule comprises the switch which can exhibit different chiralities, that is, cis-form and trans-form by ultraviolet or visible irradiation. The results clearly reveal that the switching behaviors can be realized when the molecule converts between cis-form and trans-form. ~urthermore, the on-off ratio can be modulated by the chirality of the carbon nanotube electrodes. The maximum on-off ratio can reach 109 at 0.4 V for the armchair junction, suggesting potential applications of this type of junctions in future design of functional molecular devices.

AN UNGUIDED TOUR STARTED FROM CHIRALITY

This survey article records an unguided mathematical tour by topologists at Peking University and their collaborators in the last ten years. The tour started from research on chirality and, attracted by questions around attractors, led to a zigzag path across topology and dynamics. People who joined us in this tour at various stages include Ding Fan, Liu Yi, Ni Yi, Pan Jianzhong, Yao Jiangang, Zheng Hao and Zhou Qing. Conversations with Robert Edwards, Wen Lan and others, added to the twists and turns that made the trip more fun. This article benefits from related lectures by these authors, in many conferences, universities, as well as high schools.

Chirality-asymmetry force between α-quartz and copper block

The chirality-asymmetry macroscopic force mediated by light pseudoscalar particles between a-quartz and some achiral matter is studied. If this force between achiral source mass and a-quartz with some chirality is attractive, it will become repulsive when the chirality of the a-quartz crystal is changed. According to the tested limits of the coupling constant gsgp/hc 〈 1.5×10^-24 at the Compton wavelength A = 10-3 m, the force （F） between a 0.08 × 0.08 × 0.002 m3 block of a-quartz and a 0.08 × 0.08× 0.01 m3 copper block with a separation being 0.5 × 10^-3 m in between, is estimated from the published data at less than 4.64 × 10^-24 N, i.e. F 〈 4.64 ×10^-24 N.

Quantitative Surface Chirality Detection with Sum Frequency Generation Vibrational Spectroscopy： Twin Polarization Angle Approach

Here we report a novel twin polarization angle （TPA） approach in the quantitative chirality detection with the surface sum-frequency generation vibrational spectroscopy （SFG-VS）. Generally, the achiral contribution dominates the surface SFG-VS signal, and the pure chiral signal is usually two or three orders of magnitude smaller. Therefore, it has been difficult to make quantitative detection and analysis of the chiral contributions to the surface SFG- VS signal. In the TPA method, by varying together the polarization angles of the incoming visible light and the sum frequency signal at fixed s or p polarization of the incoming infrared beam, the polarization dependent SFG signal can give not only direct signature of the chiral contribution in the total SFG-VS signal, but also the accurate measurement of the chiral and achiral components in the surface SFG signal. The general description of the TPA method is presented and the experiment test of the TPA approach is also presented for the SFG-VS from the S- and R-limonene chiral liquid surfaces. The most accurate degree of chiral excess values thus obtained for the 2878 cm^-1 spectral peak of the S- and R-limonene liquid surfaces are （23.7±0.4）% and （-25.4±1.3）%, respectively.

Coherent control of negative refraction based on local-field enhancement and dynamically induced chirality

This paper studies the electromagnetic response of a coherently driven dense atomic ensemble to a weak probe. It finds that negative refraction with little absorption may be achieved in the presence of local-field enhanced interaction and dynamically induced chirality. The complex refractive index governing the probe refraction and absorption depends critically on the atomic density, the steady population distribution, the coherence dephasings, and the frequency de- tunings, and is also sensitive to the phase of the driving field because the photonic transition paths form a close loop. Thus, it can periodically tune the refractive index at a fixed frequency from negative to positive values and vice versa just by modulating the driving phase. Moreover, the optimal negative refraction is found to be near the probe magnetic resonance, which then requires the electric fields of the probe and the drive being on two-photon resonance due to the dipole synchronisation.

Variable optical chirality in atomic assisted microcavity

The manipulating of optical waves in a microcavity is essential to developing the integrated optical devices.Generally,the two eigenmodes in a whispering-gallery-mode(WGM)microcavity possess chiral symmetry.Here we show the chiral symmetry breaking is induced by the asymmetric backscattering of counter-propagating optical waves in a whisperinggallery-mode(WGM)microcavity with a cavity-made slot filled with atomic vapor.Through tuning the dispersion relation of the atomic vapor in the cavity-made slot,the chiral modes are continuously steered.The mode frequency splitting in the transmission and reflection spectra stem from the chiral symmetry breaking of the two eigenmodes.The displacement sensitivity of the proposed system in response to the length variation of cavity-made slot exhibits a high sensitivity value of 15.22 THz/nm.

Strong chirality in twisted bilayerα-MoO_(3)

Chiral structures are promising in many applications,such as biological sensing and analytical chemistry,and have been extensively explored.In this paper,we theoretically investigate the chiral response of twisted bilayerα-MoO_(3).Firstly,the analytical formula for the transmissivity is derived when the structure is illuminated with circularly polarized plane waves.Furthermore,the results demonstrate that the twisted bilayerα-MoO_(3)can excite the strong chirality with the maximum circular dichroism(CD)of 0.89.In this case,the chirality is due to the simultaneous breaking the rotational symmetry and mirror symmetry,which originates from the relative rotation of twoα-MoO_(3)layers.To better understand the physical mechanism,the polarization conversion between the left-hand circular polarization(LCP)and right-hand circular polarization(RCP)waves is discussed as well.Moreover,it is found that the structure can maintain the strong chirality(CD>0.8)when the twisted angle varies from 69°to 80°,which effectively reduces the strictness in the requirement for rotation angle.In addition,the CD can be larger than 0.85 when the incidence angle of circularly polarized plane wave is less than 40°,implying that the chirality is robust against the angle of incidence.Our work not only provides an insight into chirality induced by the twisted bilayerα-MoO_(3),but also looks forward to applications in biolo gical sensing.

Influence of chirality on the cyclohexene-fused C_(60) fullerene derivatives as an accepter partner in a photovoltaic cell

Organic photovoltaic devices(OPVs) using chiral cyclohexene-fused [C_(60)]-fullerene derivatives that have(l)-menthyl ester moiety have been prepared and their properties evaluated as acceptor molecules with P3 HT polymer: racemic cyclohexene-fused [C_(60)] fullenene,(RS)-(1 R,2 S,5 R)-2 a showed higher PCE(2.81%) than that of standard [C_(60)]-PCBM(2.64%) under the same analysis conditions. On the contrary, devices using chiral(R)-(1 R,2 S,5 R)-2 a and(S)-(1 R,2 S,5 R)-2 a, showed PCE as 1.08% and 1.10%, respectively. The main origin of the differences in PCE was found to be their poor Jsc values. The results indicate that the aggregation state might influence the interaction state with P3 HT and impact the results of the OPV properties, Jsc values in particular.

The role of nickel(II) on the homochirality of amino acids in living systems

The origin of homochirality in living organisms is controversial,stands out of being particularly important and a question which is still not satisfactorily answered.A mental picture of sequence of events that is thought to have preceded the existence of chirality in molecules is described.A chemical model to mimic the original abiotic conditions in an attempt to explain the preference of homochirality in living systems was tried.The effect which might have influenced this preference is presented.The surpri...