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We investigate a ring polymer under the influence of chiral active Brownian forces in two dimensions using coarse-grained computer simulations. We observe a non-monotonic behavior of the radius of gyration of an active Brownian ring as a function of active force. However, the shrinkage of the ring in the intermediate strength of active forces becomes more pronounced in the presence of chiral active forces, and the shrinkage is monotonic at a given activity level as a function of the angular frequency controlling the direction of the active force. The distribution of radius of gyration, inter-monomer distance, and radial distribution suggest that the monomers come close to each other, eventually leading to the shrinkage of the ring. Moreover, the bond-correlation suggests that the chirality introduces a local folding of the monomers. Furthermore, using the diameter correlation function, we show that the ring performs tank-treading motion with a frequency following power-law relation with active force with exponent 3/2. The mean squared displacement of the monomers further assists the tank-treading dynamics by exhibiting oscillatory behavior. [ABSTRACT FROM AUTHOR]

Motivated by experimental reports on chirality induced spin selectivity, we investigate a minimal model that allows us to calculate the charge and spin conductances through helical molecules analytically. The spin–orbit interaction is assumed to be non-vanishing on the molecule and negligible in the reservoirs (leads). The band structure of the molecule features four helical modes with spin-momentum locking that are analogous of edge-currents in the quantum spin Hall effect. While charge is conserved and therefore the charge current is independent of where it is measured—reservoirs or molecule—our detailed calculations reveal that the spin currents in the left and right leads are equal in magnitudes but with opposite signs (in linear response). We predict that transport currents flowing through helical molecules are accompanied by a spin accumulation in the contact region with the same magnetization direction for source and drain. Furthermore, we predict that the spin-conductance can be extracted directly from measuring the (quasi-static) spin accumulation—rather than the spin current itself, which is very challenging to obtain experimentally. [ABSTRACT FROM AUTHOR]

The side chain dynamics of poly(quinoxaline-2,3-diyl)s (PQXs) are expected to influence their conformation. To investigate these dynamics experimentally, quasielastic neutron scattering (QENS) was performed for PQXs in deuterated tetrahydrofuran (THF-d8) and deuterated 1,1,2-trichloroethane/THF (1,1,2-TCE-d3/THF-d8), in which they formed right-handed and left-handed helical structures, respectively. The mean-square displacement of the PQX side chains in 1,1,2-TCE-d3/THF-d8 was lower than that in THF-d8. Furthermore, QENS complementary studies and molecular dynamics simulations unraveled a coupling between the main-chain and side chain dynamics of PQXs, suggesting the possibility of controlling the main-chain helical chirality through the dynamics of chiral side chains. These insights present a novel strategy for the design of synthetic helical macromolecules with precise chirality control. [ABSTRACT FROM AUTHOR]

We investigate the quantum interference of the electron–hole conversions from the two interfaces in a Weyl semimetal (WSM)-based hybrid structure, in which a superconducting WSM is sandwiched in between two normal ones. The quantum interference is characterized by the chirality-anomaly-manipulation (CAM). It is found that only low energy is in favor for s -wave BCS pairing states. The Andreev reflection (AR) chirality blockade can be tuned by the stagger angle α for the relative orientation of paired Weyl points, accompanied by an AR bipolar chirality diode. Thus, a strong CAM is indicated for the electron–hole conversion. However, the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) pairing states have no energy preference, with the weak and strong CAMs being near and far away from the zero energy, respectively. More interestingly, a perfect AR with the normal reflection suppressed thoroughly can be obtained at any α as a result of the FFLO paring with the same chirality. In addition, the conductance or noise power, which incorporates the contributions of the two paired Weyl nodes, not only, in turn, embodies the respective features of their contributions but also can be experimentally measured to discern between the BCS and FFLO paring states. [ABSTRACT FROM AUTHOR]

Chirality ubiquitously appears in nature; however, its quantification remains obscure owing to the lack of microscopic description at the quantum-mechanical level. We propose a way of evaluating chirality in terms of the electric toroidal monopole, a practical entity of time-reversal even pseudoscalar (parity-odd) objects reflecting relevant electronic wave functions. For this purpose, we analyze a twisted methane molecule at the quantum-mechanical level, showing that the electric toroidal monopoles become a quantitative indicator for chirality. In the twisted methane, we clarify that the handedness of chirality corresponds to the sign of the expectation value of the electric toroidal monopole and that the most important ingredient is the modulation of the spin-dependent imaginary hopping between the hydrogen atoms, while the relativistic spin–orbit coupling within the carbon atom is irrelevant for chirality. [ABSTRACT FROM AUTHOR]

Molecular chirality has traditionally been viewed as a binary property where a molecule is classified as either chiral or achiral, yet in recent decades, mathematical methods for quantifying chirality have been explored. Here, we use toy molecular systems to systematically compare the performance of two state-of-the-art chirality measures: (1) the Continuous Chirality Measure (CCM) and (2) the Chirality Characteristic (χ). We find that both methods exhibit qualitatively similar behavior when applied to simple molecular systems such as a four-site molecule or the polymer double-helix, but we show that the CCM may be more suitable for evaluating the chirality of arbitrary molecules or abstract structures such as normal vibrational modes. We discuss a range of considerations for applying these methods to molecular systems in general, and we provide links to user-friendly codes for both methods. We aim for this paper to serve as a concise resource for scientists attempting to familiarize themselves with these chirality measures or attempting to implement chirality measures in their own work. [ABSTRACT FROM AUTHOR]

Chiral molecules can exhibit strong spin–orbit coupling, which can result in a large spin polarization. This is due to the fact that the energy levels of the electrons in a chiral molecule are strongly influenced by the chiral structure of the molecule, which can result in the separation of the energy levels for electrons with different spin orientations. We report a controlled spin-selective transmission of electrons through 20 base-paired poly-cytosine molecules functionalized with MoS2 flakes on ITO glass via the quantum mechanical tunneling effect. A reversion in spin polarization was observed after the silver ions interact with poly-cytosine due to the strong coordination of Ag(I) with cytosine–cytosine (C–C) mismatches, indicating the formation of duplex structural motifs, as confirmed by the circular dichroism spectroscopy at room temperature. Manipulating the spin of an electron through such a small molecule merely controlled by special cations could pave the way for major advances in spin-independent charge transport, advanced bioanalytical system design, and related applications. [ABSTRACT FROM AUTHOR]

Chiral molecules can exhibit strong spin–orbit coupling, which can result in a large spin polarization. This is due to the fact that the energy levels of the electrons in a chiral molecule are strongly influenced by the chiral structure of the molecule, which can result in the separation of the energy levels for electrons with different spin orientations. We report a controlled spin-selective transmission of electrons through 20 base-paired poly-cytosine molecules functionalized with MoS2 flakes on ITO glass via the quantum mechanical tunneling effect. A reversion in spin polarization was observed after the silver ions interact with poly-cytosine due to the strong coordination of Ag(I) with cytosine–cytosine (C–C) mismatches, indicating the formation of duplex structural motifs, as confirmed by the circular dichroism spectroscopy at room temperature. Manipulating the spin of an electron through such a small molecule merely controlled by special cations could pave the way for major advances in spin-independent charge transport, advanced bioanalytical system design, and related applications. [ABSTRACT FROM AUTHOR]

Molecular chirality is represented as broken mirror symmetry in the structural orientation of constituent atoms and plays a pivotal role at every scale of nature. Since the discovery of the chiroptic property of chiral molecules, the characterization of molecular chirality is important in the fields of biology, physics, and chemistry. Over the centuries, the field of optical chiral sensing was based on chiral light–matter interactions between chiral molecules and polarized light. Starting from simple optics-based sensing, the utilization of plasmonic materials that could control local chiral light–matter interactions by squeezing light into molecules successfully facilitated chiral sensing into noninvasive, ultrasensitive, and accurate detection. In this Review, the importance of plasmonic materials and their engineering in chiral sensing are discussed based on the principle of chiral light–matter interactions and the theory of optical chirality and chiral perturbation; thus, this Review can serve as a milestone for the proper design and utilization of plasmonic nanostructures for improved chiral sensing. [ABSTRACT FROM AUTHOR]

Chiral hybrid lead halide perovskites show interesting chiral optoelectronic properties. The extent of chirality is often estimated by their circular dichroism (CD) response. Here, we show that the CD data depend strongly on film morphology. Four of the six chiral hybrid lead halide films prepared, 2D (R- and S-MBA)2PbI4 and 1D (R- and S-MBA)PbI3 (MBA: methylbenzylammonium), form homogenous non-textured films and show an isotropic CD signal. In contrast, the other two samples, 1D (R- and S-MBA)PbBr3, form textured films, showing uncorrelated CD signals from different parts of the film. Therefore, the role of film morphology needs to be verified before designing and comparing the chiroptic and chiral optoelectronic properties of hybrid perovskites. [ABSTRACT FROM AUTHOR]

In connection to the chiral-induced spin selectivity effect, we theoretically analyze the electronic and spin states of edges of a finite p-orbital helical atomic chain with the intra-atomic spin–orbit interaction. This model can host the spin-filtering state in which two up-spins propagate in one direction and two down-spins propagate in the opposite direction without breaking the time-reversal symmetry (TRS). The enhancement of charge modulations concentrated at the edges due to the evanescent states is induced, although the spin density is absent because of the TRS. A Zeeman field at an edge of the atomic chain, which breaks the TRS, yields a finite spin polarization, whose direction depends on the chirality of the molecule. The chirality change induces a reasonable amount of the energy difference, which may provide an insight into the enantioselective adsorption of chiral molecules on the ferromagnetic surface. [ABSTRACT FROM AUTHOR]

Motivated by the booming development of spintronics based on chiral helical microstructures, we employed the standard nonequilibrium Green's function theory to study nonreciprocity and chirality of the heat generation and spin filtering in ferromagnetic helical chains. Our results demonstrate that magnetization, spin–orbit interaction, and nonstep electrostatic potential distribution by bias jointly determine nonreciprocity of the heat generation, and only spin–orbit interaction determines nonreciprocity of the spin-polarized current. Chirality of the heat generation and spin-polarized current is determined by both magnetization and spin–orbit interaction, and some quantitative relationships related to chirality were discovered. However, a transverse field can break these relations and suppress heat generation significantly and modulate nonreciprocity and chirality of the spin-polarized current effectively. By further simulating the critical electrostatic potential distribution, we found with the transverse field applied, compared to the case with zero temperature, that the finite temperature less than one characteristic phonon energy can suppress nonreciprocity of the heat generation while enhancing that of the spin filtering. In terms of chirality, compared to the left-handed helical structure, the right-handed one is more advantageous for designing spin filtering diodes. [ABSTRACT FROM AUTHOR]

The ability to accurately monitor chiral biological molecules is of great significance for their potential applications in disease diagnosis and virus detection. As the existing chiral detection technologies are mainly relying on an optical method by using left/right circularly polarized light, the universality is low and the operation is complicated. Moreover, large quantity of chiral molecules is required, causing low detection efficiency. Here, a self-assembled monolayer of polypeptides has been fabricated to realize trace detection of chirality based on spin selectivity of photon–electron interaction. We have utilized Kerr technique to detect the rotation angle by the molecular monolayer, which indicates the chirality of polypeptides. The chiral structure of a biological molecule could result in spin-selectivity of electrons and thus influence the interaction between electron spin and light polarization. A Kerr rotation angle of ∼3° has been obviously observed, equivalent to the magneto-optic Kerr effect without magnetic material or magnetic field. Furthermore, we have provided a novel solution to achieve chirality discrimination and amplification simultaneously through an optical fiber. The proposed design is applicable for chiral detection via increasing their differential output signal, which clearly demonstrates a useful strategy toward chirality characterization of biological molecules. [ABSTRACT FROM AUTHOR]

By now, it is well known that chiral molecules can affect the spin of electrons passing through. In addition, the magnetization of, e.g., nanomagnets covered by chiral molecules can be affected by the presence of molecules. We are studying the mechanisms that explain various observations involving combinations of magnets and chiral molecules. We find that there exists a molecule induced contribution to the magnetic anisotropy of the magnets. Out of equilibrium, when electrons are actually being transported through a nano-magnet covered with chiral molecules, a molecule induced torque acting on the magnetization is emerging. It is of the spin-transfer-torque kind, already discussed in other parts of spintronics. This current induced torque can help explain the observed breaking of the Onsager reciprocity principle in experiments involving magnets and chiral molecules. [ABSTRACT FROM AUTHOR]

Chiral materials exhibit many interesting physical properties including circular dichroism, circularly polarized photoluminescence, and spin selectivity. Since its discovery, chirality-induced spin selectivity (CISS) has been demonstrated in many chiral material systems, which indicates promising applications in spintronic devices. Thus, searching for compounds that possess both sizable chirality and excellent spin transport properties is in order. Hybrid organic–inorganic perovskites have attracted intensive research interest due to their long carrier lifetime, high carrier mobility, chemically tunable electronic properties, and long spin lifetime, which make this emerging class of semiconductors promising candidate for spintronics. Moreover, hybrid perovskites integrate inorganic octahedral framework and organic ligands, which may introduce chirality into the materials, especially in quasi-two-dimensional structures. Recently, CISS has been observed in 2D chiral hybrid perovskites, showing the spin filtering effect. Studies of CISS in chiral hybrid perovskites not only help deepen our understanding of CISS mechanism but also shed new light on designing novel spintronic devices. In this review, we summarize the state-of-the-art studies of CISS effect in 2D chiral hybrid organic–inorganic perovskites system. We also discuss the remaining challenges and research opportunities of employing CISS in next-generation spintronic devices. [ABSTRACT FROM AUTHOR]

The hydrodynamic interaction between two chiral organisms (chirality parameter 0 ≤ C2 ≤ 10) swimming toward each other is investigated using the lattice Boltzmann method over a Reynolds number range of 0.01 ≤ Re ≤ 5, with the swimming parameter β = ±5. Our findings reveal that in a finite inertial flow regime, with a low C2 for chiral squirmers, enhancing the C2 leads to a strengthened attraction between pullers (a type of squirmer) and other chiral squirmers. Simultaneously, this strengthening reduces the repulsive tendencies observed in pushers (another type of squirmer). Beyond a certain threshold (C2 ≥ 5), an increase in the C2 causes the flow field generated by a pusher to resemble that of a puller, there by initiating an attractive influence on another squirmer. At this point, with an increase in C2, the mutual attraction between pullers and pushers intensifies. Moreover, as the C2 continues to increase, the duration of the intense interaction between colliding pullers or pushers steadily diminishes, contrasting with the increased duration of the intense interaction between non-colliding pushers. These empirical insights substantively enhance our comprehension and empirical investigation of collective behavioral dynamics in chiral microorganisms. [ABSTRACT FROM AUTHOR]

It has been demonstrated previously that electrons interact differently with chiral molecules depending on their polarization. For enantiomeric pure monolayers of heptahelicene, opposite asymmetries in spin polarization were reported and attributed to the so-called chirality-induced spin selectivity effect. However, these promising proof-of-concept photoemission experiments lack the angular and energy resolution that could provide the necessary insights into the mechanism of this phenomenon. In order to fill in the missing gaps, we provide a detailed spin- and angle-resolved photoemission spectroscopy study of heptahelicene layers on a Cu(111) substrate. Throughout the large accessible energy and angle range, no chirality induced spin asymmetry in photoemission could be observed. Possible reasons for the absence of signatures of the spin-dependent electron transmission through the chiral molecular layer are briefly discussed. [ABSTRACT FROM AUTHOR]

Spin–orbit coupling in a chiral medium is generally assumed to be a necessary ingredient for the observation of the chirality-induced spin selectivity (CISS) effect. However, some recent studies have suggested that CISS may manifest even when the chiral medium has zero spin–orbit coupling. In such systems, CISS may arise due to an orbital polarization effect, which generates an electromagnetochiral anisotropy in two-terminal conductance. Here, we examine these concepts using a chirally functionalized carbon nanotube network as the chiral medium. A transverse measurement geometry is used, which nullifies any electromagnetochiral contribution but still exhibits the tell-tale signs of the CISS effect. This suggests that CISS may not be explained solely by electromagnetochiral effects. The role of nanotube spin–orbit coupling on the observed pure CISS signal is studied by systematically varying nanotube diameter. We find that the magnitude of the CISS signal scales proportionately with the spin–orbit coupling strength of the nanotubes. We also find that nanotube diameter dictates the supramolecular chirality of the medium, which in turn determines the sign of the CISS signal. [ABSTRACT FROM AUTHOR]

We demonstrate that angular momentum selectivity of particles traversing chiral environments is not limited to the quantum regime and can be realized in classical scenarios also. In our classical variant, the electron spin, which is central to the quantum chirality induced spin selectivity (CISS) effect, is replaced by the self-rotation of a finite-volume body. The latter is coupled to the center of mass orbital motion of the body through a helical tube via wall friction that acts as a dissipative spin–orbit coupling term. As a specific example, we study C60 molecules that are initially spinning in opposite senses and investigate the effect of various external control parameters on their spatial separation when driven through a rigid helical channel. We highlight resemblances and inherent differences between the quantum CISS effect and its classical variant and discuss the potential of the latter to formulate a new paradigm for enantio-separation. [ABSTRACT FROM AUTHOR]

Observations of a high spin selectivity in various helical structures, which is called the chirality-induced spin selectivity, suggest a common mechanism originating from the helical geometry. In this paper, we consider a helical chain of atomic p± orbitals having the tangential angular momentum l = ±1. We show in this model that the coupling of l and the spin gives rise to spin-velocity locking, i.e., directions of spin and group velocity are parallel or antiparallel depending on the chirality of the helix, and consequently, an almost perfect spin selectivity in a specific energy region in a wide range of the curvature and the torsion of the helix. We find that the present spin-velocity locking originates from the helical symmetry in which the Hamiltonian is invariant with respect to a combined operation of the rotation around the helix axis and the translation along the helix axis. Therefore, we expect that spin-velocity locking occurs in a wide variety of helical structures. [ABSTRACT FROM AUTHOR]

Chiral functionalities exhibited by systems lacking any mirror symmetry encompass natural optical activity, magnetochiral effect, diagonal current-induced magnetization, chirality-selective spin-polarized current of charged electrons or neutral neutrons, self-inductance, and chiral phonons. These phenomena are unified under the hypothesis of "kinetomagnetism of chirality," which posits that any moving (charged or neutral) object in chiral systems induces magnetization in its direction of motion, consequently imparting chirality to the object due to this induced magnetization. We also found conjugate relationships among the kinetomagnetism of chirality, "linear magnetoelectricity," and "electric field-induced directional nonreciprocity," highlighting their interconnections with magnetic, electric, and toroidal orders. The concept of the kinetomagnetism of chirality will be an essential basis for the theoretical understanding of known chiral phenomena, such as natural optical activity or chiral phonons, and also the discovery of unexplored chiral functionalities. [ABSTRACT FROM AUTHOR]

The presented study suggests a silicon photonic topological insulator with triple Dirac points, each associated with a specific valley; there is a contrast in the chirality (handedness) of the photon states between these valleys. This contrasting chirality results in interesting optical properties, potentially leading to topologically protected robust wave guiding effect in compact structure with sharp edge. [ABSTRACT FROM AUTHOR]

In this work, chirality in spin-active electronic states is explained clearly to address confusion about chiral effects recently discovered in materials science. We stress that the electronic toroidal monopole G0 can serve as a measure of chirality. By using the symmetry classification in terms of four distinct types of multipole bases, we extend the concept of chirality from materials to physical fields and material-field composites. Additionally, we illustrate specific examples from physics and chemistry that demonstrate the process of acquiring chirality through the combination of seemingly achiral degrees of freedom, which we term the emergence of chirality. Interference between multiple chiralities exhibiting phenomena specific to handedness is also discussed. [ABSTRACT FROM AUTHOR]

Heavy metal/ferromagnet interfaces in systems with perpendicular magnetic anisotropy (PMA) hosts chiral Néel wall with the assistance of interfacial Dzyaloshinskii–Moriya interaction (iDMI). We have investigated field induced domain wall motion in the creep regime to estimate the effective iDMI strength, D eff of sputter-deposited Ta/Pt/Co/Pt and Ta/Pt/Co/Au/Pt thin films that exhibit PMA. Two similar Pt/Co interfaces on either side of the Co layer in the Ta/Pt/Co/Pt system lead to a small D eff with a negative sign that supports the Néel type domain wall of right-handed chirality. Ultrathin Au layers of different thicknesses have been deposited at the top Co/Pt interface to introduce asymmetry around the Co layer and control the D eff . Here, two interfaces (Pt/Co and Au/Co) of opposite iDMI polarity have been chosen to invert the domain wall chirality to the left-handed chirality instead of the right-handed chirality found in the Ta/Pt/Co/Pt system. [ABSTRACT FROM AUTHOR]

One-dimensional single-wall carbon nanotube (1D-SWCNT)@MoS2 van der Waals (vdW) heteronanotubes (HNTs) have inherited extensive attention due to their fascinating properties and increasing mature methods. However, the curvature and chirality dependence of photovoltaic properties in such kind of 1D systems remain unclear. In our work, we explore the electronic and photoelectric properties of 1D-SWCNT@MoS2 vdW HNTs based on the atomic-bond-relaxation approach and the modified detailed balance principle by quantization of band offset and carrier transport behaviors. We find that the optimized power conversion efficiency (PCE) of zigzag-SWCNT@zigzag-MoS2 HNTs is ∼5.3% at the diameter of 3.1 nm, while that of zigzag-SWCNT@armchair-MoS2 HNTs is ∼4.9% at 3.3 nm. Moreover, the PCE can be enhanced further by intercalating h-BN layers at the interface of 1D-vdW HNTs. Our results suggest that 1D-SWCNT@MoS2 HNTs can be served as promising building blocks for the new type of photovoltaic devices. [ABSTRACT FROM AUTHOR]

We propose a hybrid magnonic-oscillator system based on the combination of a spin transfer auto-oscillator and a magnonic waveguide to open new perspectives for spin-wave based circuits. The system is composed of a spin transfer oscillator based on a vortex state which is dipolarly coupled to a nanoscale spin-wave waveguide with longitudinal magnetization. In its auto-oscillating regime, the oscillator emits coherent spin waves with tunable and controllable frequencies, directions, and amplitudes into the waveguide. We demonstrate the principle of this method using micromagnetic simulations and show that reconfiguration of the system is possible by changing the chirality and polarity of the magnetic vortex. Spin waves are emitted into the waveguide with high non-reciprocity and the preferred direction depends on the core polarity of the vortex. In contrast, different vortex chiralities lead to different amplitudes of the emitted waves. Our findings open up a novel way to design an agile spintronic device for the coherent and tunable generation of propagating spin waves. [ABSTRACT FROM AUTHOR]

In this Perspective article, we briefly present the current state and discuss some future perspectives on hybrid molecular spintronics and smart molecular spintronics materials. We discuss the role of the chirality induced spin selectivity effect, where molecular chirality can be employed to manipulate spin states, potentially also including quantum coherent spin qubit states. We comment on some of the challenges and suggest future potential of magnetic biomolecules and chemical modification of 2D materials for these purposes. [ABSTRACT FROM AUTHOR]

We present a strategy for realizing the nonvolatile electrical control of noncollinear magnetism based on first-principles calculations. We confirm that the VAl2S4 monolayer, a rare two-dimensional type-II multiferroic material, shows an in-plane noncollinear 120°-ordered antiferromagnetic ground state and spin spiral order induced out-of-plane ferroelectricity. In VAl2S4 bilayers, we clarify the spin spiral chirality–sliding ferroelectricity locking effect, which enables flexible electrical switching of noncollinear magnetism and corresponding spin spiral chirality through interlayer sliding. Our work provides another perspective for the development of magnetoelectric physics and information storage devices. [ABSTRACT FROM AUTHOR]

We have observed robust chiral spin torques and non-reciprocal charge transport behaviors in the α-Fe2O3/Pt bilayers through a combination of magnetic field and current-dependent second longitudinal harmonic resistance measurements. The interfacial Dzyaloshinskii–Moriya interaction induced magnetic chirality has been predicted to account for the sign reversal characteristic of the second longitudinal harmonic resistance with increasing the current amplitude. A physical model that considers the chirality dependence of both the asymmetric scattering and the giant Rashba spin–orbit coupling has been set up to uncover the microscopic interactions between charge, spin, and magnetic chirality. Our comprehensive approach leverages the semiclassical Boltzmann theory to validate the consistency between this model and our experimental findings. Through our investigation, we have established the pivotal role of interfacial magnetic chirality in determining both charge and spin transport behaviors within antiferromagnetic insulator/heavy metal bilayer systems. Our work not only enhances the comprehension of spin–orbit torques and non-reciprocal charge transport but also contributes to the broader understanding of these phenomena. The outcomes of this study have broader implications for the advancement of spintronics and related fields. [ABSTRACT FROM AUTHOR]

Enantiomer sorting greatly promotes the advancement of chemistry, bioscience, and medicine while also facing significant challenges. Recently, all-optical solutions have attracted considerable interest due to their non-invasiveness. While, it should be noted that the achiral optical force is always much larger than the chiral gradient force that plays a key role in all-optical enantiomer sorting, hindering the separation of enantiomers. Previously proposed methods to boost the chiral gradient forces by plasmonic and photonic nanostructures are often accompanied by the enhancement of achiral optical forces. The sorted chiral particles are also difficult to be transferred from the complex nanostructures. Here, we propose an approach for separating enantiomers using uniform light field formed by two waves, which is capable of sorting deep sub-wavelength chiral particles. In our method, the chiral particles can be sorted within a simple planar structure while the achiral gradient force is equal to zero. Our research reveals a promising perspective on large-scale sorting for enantiomers. [ABSTRACT FROM AUTHOR]

3D nano-superconductors, with non-trivial geometry-driven topological phenomena, stand as promising systems for the future evolution of efficient and multifunctional technologies. However, the substantial challenges inherent in the experimental work, particularly regarding the fabrication and characterization of 3D nanoscale geometries and unconventional topologies of superconducting states, have confined the majority of investigations in this domain until recently to the realms of computational and theoretical studies. We overview the recent advancements in fabricating superconductor 3D nanoarchitectures and unveiling their fascinating physical properties that occur due to the geometry-induced topology and chirality, which offer a broad spectrum of applications of these nanostructures for the front-line development of various modern technologies. [ABSTRACT FROM AUTHOR]

Recently, researchers have devoted their intense efforts to investigating Weyl physics in synthetic space. In this Letter, we study the intriguing topological rotated Weyl physics in a three-dimensional parameter space, which consists of two extra structural parameters and the wave vector of a simple one-dimensional sonic crystal. In our ultrasonic experiments, we observe that the topological interface states propagate along the interface formed by two sonic crystals of distinct chirality caused by the rotated Weyl points. We detect the rotated synthetic Weyl points and measure the singularities of the reflection phase, which results in the robustness of the interface states. At the same time, it also shows the advantages of synthetic dimensions in exploring high-dimensional physics problems in low-dimensional systems. [ABSTRACT FROM AUTHOR]

Cell chirality is crucial for the chiral morphogenesis of biological tissues, yet its underlying mechanism remains unclear. Cell organelle polarization along multiple axes in a cell body, namely, apical–basal, front–rear, and left–right, is known to direct cell behavior such as orientation, rotation, and migration. Among these axes, the left–right bias holds significant sway in determining the chiral directionality of these behaviors. Normally, mouse myoblast (C2C12) cells exhibit a strong counterclockwise chirality on a ring-shaped micropattern, whereas they display a clockwise dominant chirality under Latrunculin A treatment. To investigate the relationship between multicellular chirality and organelle positioning in single cells, we studied the left–right positioning of cell organelles under distinct cell chirality in single cells via micropatterning technique, fluorescent microscopy, and imaging analysis. We found that on a "T"-shaped micropattern, a C2C12 cell adopts a triangular shape, with its nucleus–centrosome axis pointing toward the top-right direction of the "T." Several other organelles, including the Golgi apparatus, lysosomes, actin filaments, and microtubules, showed a preference to polarize on one side of the axis, indicating the universality of the left–right asymmetrical organelle positioning. Interestingly, upon reversing cell chirality with Latrunculin A, the organelles correspondingly reversed their left–right positioning bias, as suggested by the consistently biased metabolism and contractile properties at the leading edge. This left–right asymmetry in organelle positioning may help predict cell migration direction and serve as a potential marker for identifying cell chirality in biological models. [ABSTRACT FROM AUTHOR]

Suppression of the Walker breakdown in confined wires is key to improving the operation and reliability of magnetic domain-wall-based devices, including logic, memory, and sensor applications. Here, via micromagnetic simulations, we demonstrate that periodical wire-width modulation with suitable geometric parameters can fully suppress the Walker breakdown of a field-driven domain wall, conserving its spin structure in the whole operating field range of a device. Key differences in the efficacy of the wire-width modulation are observed for wires with different widths and thicknesses such that different domain wall states are energetically stable. In particular, the approach is found to be effective in expanding the field-operating window of a device in the case of smaller wire widths and thicknesses (below 150 nm wide and 15 nm thick), whereas in larger wires, the advantages from the suppression in the Walker breakdown are counteracted by the increase in domain wall pinning and the reduction in the nucleation field for new domain walls. Simulations on intersecting magnetic wires prove the importance of suppression of the Walker breakdown. Since the domain wall behavior is chirality dependent, introducing periodical wire-width modulation conserves the spin structure, thus reducing stochasticity of the domain wall propagation. [ABSTRACT FROM AUTHOR]

We have theoretically studied spin- and valley-transport properties in a silicene quantum structure with a square magnetic barrier modulated by off-resonant circularly polarized light (OCPL). The result shows that in the magnetic quantum structure, valley and spin filtering can be realized simultaneously with appropriate OCPL at small incident angles. More interestingly, at normal incidence, Klein tunneling is observed in the K ′ valley. Besides, it is also found that valley polarization can be inverted by reversing the sign of the staggered potential or the chirality of OCPL. Nevertheless, the direction of spin polarization can only be modulated by the chirality of OCPL. These findings provide the potential applications for constructing novel type of silicene devices. [ABSTRACT FROM AUTHOR]

We consider chirality in active systems by exemplarily studying the phase behavior of planar systems of interacting Brownian circle swimmers with a spherical shape. For this purpose, we derive a predictive field theory that is able to describe the collective dynamics of circle swimmers. The theory yields a mapping between circle swimmers and noncircling active Brownian particles and predicts that the angular propulsion of the particles leads to a suppression of their motility-induced phase separation, being in line with recent simulation results. In addition, the theory provides analytical expressions for the spinodal corresponding to the onset of motility-induced phase separation and the associated critical point as well as for their dependence on the angular propulsion of the circle swimmers. We confirm our findings by Brownian dynamics simulations. Agreement between results from theory and simulations is found to be good. [ABSTRACT FROM AUTHOR]

As a geometric property that cannot overlap with its mirror image, chirality is becoming more and more common in electronic structures. The recent discovery of chiral topological polar structures in artificial ferroelectric superlattices is not only of scientific importance but also holds promise for application in tunable frequency oscillators. Although the tubular chiral polarization vortex has been observed in PbTiO3/SrTiO3 superlattices, the conditions for its stability remain elusive. Here, we construct a temperature-strain phase diagram for the (PbTiO3)10/(SrTiO3)10 superlattices by using phase field simulation in which four domain states exist at different temperatures and misfit strains. It is found that the chiral polarization vortex appears only in a small range of misfit strain, elucidating the absence of chirality in most ferroelectric superlattices. The chiral polarization vortex is an intermediate state between the ordinary achiral polarization vortex and the mixed domain structure. In addition, by changing strain or temperature, chiral vortices can be reversibly transformed into achiral vortices, demonstrating its tunability. The present work provides theoretical guidance for creating the chiral vortex in ferroelectric superlattices. [ABSTRACT FROM AUTHOR]

We present a formulation and implementation of anisotropic and isotropic electronic circular dichroism (ECD) using the full semi-classical light–matter interaction operator within a four-component relativistic framework. Our treatment uniquely accounts for both beyond-first-order light–matter interactions and relativistic effects, enabling us to investigate the ECD response across the electromagnetic spectrum from optical to x-ray wavelengths where relativistic selection rules and spatial field variations gain increasing importance. We consider the isotropic and oriented ECD across the valence transition and sulfur L- and K-edge transitions in the simplest disulfides, H2S2 and (CH3S)2, and evaluate the influence of the full interaction by comparing to a traditional truncated formulation in the Coulomb gauge (velocity representation). Additionally, we demonstrate that in the relativistic formalism, it is possible to work in the velocity representation, hence keeping order-by-order gauge-origin invariance, contrary to the multipolar gauge, yet being able to distinguish electric and magnetic multipole contributions. Going beyond a first-order treatment in the wave vector is mandatory in the higher-energy end of the soft x-ray region and beyond where the consequent intensity redistribution becomes significant. While the sulfur K-edge absorption spectrum is essentially unaffected by this redistribution, the signed differential counterpart is not: At least third-order contributions are required to describe the differential absorption profile that is otherwise overestimated by a factor of about two. The first-order description deteriorates at higher transition energies (beyond ∼1000 eV) where it may even fail to predict the sign of individual differential oscillator strengths. [ABSTRACT FROM AUTHOR]

Once the concept of chiral molecules was proposed, the task of chiral resolution has accompanied around in the related area. Naturally, scientists need fast and accurate methods to distinguish different chiralities. Here, we show a feasible method based on non-adiabatic holonomic quantum computation (NHQC), which can achieve over 99% discrimination of different chiralities. Based on the original scheme, we studied the modified version, NHQC+. The experimental data proved that it has better robustness than the original protocol, indicating a promising development in the relevant fields. [ABSTRACT FROM AUTHOR]

Chiral phonons have attracted increasing attention, as they play important roles in many different systems and processes. However, a method to control phonon chirality by external fields is still lacking. Here, we propose that in displacement-type ferroelectric materials, an external electric field can reverse the chirality of chiral phonons via ferroelectric switching. Using first-principles calculations, we demonstrate this point in the well-known two-dimensional ferroelectric In2Se3. This reversal may lead to a number of electrically switchable phenomena, such as chiral phonon induced magnetization, the phonon Hall effect, and possible topological interface chiral phonon modes at ferroelectric domain boundaries. Our work offers a way to control chiral phonons, which could be useful for the design and application of thermal or information devices based on them. [ABSTRACT FROM AUTHOR]

Coupled cavities are of interest as they expose qualitatively new effects, such as non-Hermitian properties, which are beyond the possibilities of individual cavities. Here, we investigate the coupling between two dielectric two-dimensional microdisk cavities and compare circular vs deformed (limaçon) resonator shapes as a function of their distance and address the effect of coupling on the far-field emission properties. We find that the asymmetric coupling characteristic for non-circular, deformed cavities induces non-Hermitian properties prominently evident in a mode-dependent chirality of the coupled cavity modes. We use an analytical model to explain our findings and reveal the direct connection between coupling asymmetry and the resulting sense of rotation of the coupled modes. While the overall far-field directionality remains robust for intercavity distances larger than two wavelengths, we observe enhanced and reversed emission for smaller distances even for only two coupled cavities. Our findings could prove useful for future applications, such as far-field emission control and sensing. [ABSTRACT FROM AUTHOR]

In this Perspective, we summarize the current state-of-the-art and the challenges of optical chirality logic computing. We discuss the prospects of its applications in integrated photonics, quantum technologies, and other multifunctional optoelectronics for ultrafast data processing. [ABSTRACT FROM AUTHOR]

We have studied the effect of chirality of the magnetization precession on the emission and scattering of spin waves from interfaces between ferromagnets with antiparallel magnetization. The need to match the chirality of the magnetization precessions at such interfaces promotes coupling between propagating modes on one side of the interface and evanescent modes on the other. This leads to the following two major effects: (i) an asymmetrical (ultimately, unidirectional) emission of spin waves from such interfaces when they are driven by an elliptically polarized magnetic field, and (ii) a strong (ultimately, complete) suppression of the transmission of spin waves incident upon such interfaces. Our results are relevant to the construction of spin-wave devices and more generally to the interpretation of measurements and numerical simulations in the field of chiral magnonics. [ABSTRACT FROM AUTHOR]

Chirality of antiferromagnetic spin waves as an intrinsic degree of freedom has been attracting considerable attention due to its potential applications for magnonic devices. In this paper, atomistic-scale dynamics simulations were conducted to investigate the chirality of spin wave resonant modes in ferrimagnetic alloy GdxFe1−x (0 < x <1) under different proportion x and external magnetic fields near the angular momentum compensation point. Simulation results reveal that as the proportion of Gd increases, the resonance mode of spin waves undergoes two distinct handedness flipping at magnetization compensation point and angular momentum compensation point. When the proportion x deviates from the magnetization compensation point, a frequency degeneracy point emerges at a non-zero magnetic field, indicating that the chirality of spin waves can also be switched by an external magnetic field. A theoretical analysis is developed to explain the observed phenomena. These findings provide valuable insights into the control and manipulation of spin wave chirality in ferrimagnetic alloys, with potential implications for the development of spin-based devices and technologies. [ABSTRACT FROM AUTHOR]

Spiral beams (SBs) have attracted increasing attention in structured light fields owing to their chirality and rich modes. However, the wrench force of existing SBs is uncontrollable and nonadjustable, which greatly limits the complex applications of particle manipulation. To address this issue, we proposed a woven spiral beam (WSB) with a controllable force field. The WSB was constructed by reshaping multispiral beams woven through an SB. The proposed WSB has flexible adjustable intensity lobes, which are easy to modulate independently, including size, position, helicity, and phase gradient. Furthermore, the WSBs were used to experimentally execute important particle manipulations, such as aggregation/disaggregation and sorting. This study provides an alternative scheme for the functional applications of SBs, which leads to different application scenarios in optical manipulations. [ABSTRACT FROM AUTHOR]

As a kind of phase singularity in physical systems, exceptional points (EPs) give rise to a plethora of counterintuitive phenomena, such as the asymmetric state transfer and unidirectional reflection. Especially, the eigenvectors of EP are self-orthogonal, and an inherent chirality can be determined because of the "missing dimension." Beyond traditional wisdom, in this work, we proposed theoretically an effective anti-parity-time symmetry in a non-Hermitian system under the external excitation, and the chirality reversal from resonance EP to absorption EP is demonstrated experimentally. The essence of this phenomenon is that the external input is involved in the establishment of the eigenstates of the system. Moreover, the critical condition of chirality reversal between two types of EPs in the non-Hermitian system is analytically given. This external excitation-controlled EP not only paves an effective way to study the fundamental non-Hermitian physics in an open system but also holds great potential in the applied photonic devices such as the chiral antenna, polarization converter, and wireless communication. [ABSTRACT FROM AUTHOR]

In condensed systems, Weyl quasiparticles have a massless nature and exhibit various relativistic chiral phenomena such as Klein tunneling, chiral anomaly, and Fermi arc surface states. However, in photonic systems, Weyl points (WPs) are protected by the D2d symmetry, often leading to multiple chiral WPs at the same energy level, which makes generating chirality-related effects challenging. To overcome this hinderance, a perturbation that breaks mirror symmetry in the metallic saddle structure was introduced. This perturbation effectively separates the energies of distinct chiral WPs, enabling the experimental measurement of the spectral intensity for each Weyl band and the assessment of chirality imbalance among the WPs. By maintaining time-reversal symmetry, the present study offers an approach for investigating the imbalance in the chirality of pseudo-fermionic fields in photonic materials. [ABSTRACT FROM AUTHOR]

Very recently, the construction of twist actuators from magnetorheological gels and elastomers has been suggested. These materials consist of magnetizable colloidal particles embedded in a soft elastic polymeric environment. The twist actuation is enabled by a net chirality of the internal particle arrangement. Upon magnetization by a homogeneous external magnetic field, the systems feature an overall torsional deformation around the magnetization direction. Starting from a discrete minimal mesoscopic model setup, we work toward a macroscopic characterization. The two scales are linked by identifying expressions for the macroscopic system parameters as functions of the mesoscopic model parameters. In this way, the observed behavior of a macroscopic system can, in principle, be mapped to and illustratively be understood from an appropriate mesoscopic picture. Our results apply equally well to corresponding soft electrorheological gels and elastomers. [ABSTRACT FROM AUTHOR]

Herein, we present the fabrication of multiplexed single-walled carbon nanotube (SWCNT) devices, where selected chiralities were separately immobilized on one chip with single-tube precision. Each chirality was subsequently electrically measured individually. Specifically, (6,5) and (7,5) SWCNT species were isolated via aqueous two-phase polymer systems, after which dielectrophoresis was used to precisely control the placement of each chirality, along with a metallic species, separately on prepatterned electrodes on a single chip. [ABSTRACT FROM AUTHOR]