Asymmetric Splitting Research Articles

Solution and Surface Solvation of Nitrate Anions with Iron(III) and Aluminum(III) in Aqueous Environments: A Raman and Vibrational Sum Frequency Generation Study.

Hydrated trivalent metal nitrate salts, Fe(NO3)3·9H2O and Al(NO3)3·9H2O, in both solid and aqueous phases are investigated. Raman and surface-selective vibrational sum frequency generation (SFG) spectroscopy, are used to shed light on ion-ion interactions and hydration in several spectral regions spanning low frequency (440-550 cm-1) to higher frequency modes of nitrate and water (720, 1050, 1250-1450, and 2800-3750 cm-1). These frequencies span the metal-water mode, nitrate in-plane deformation, nitrate symmetric and asymmetric modes, and the OH stretch of condensed phase water molecules. Comparison to NaNO3, and in some cases KNO3, is also shown, providing insight. Splitting and frequency shifts are observed and discussed for both the solid state and solution phase. The Lewis acidity of Fe3+ and Al3+ ions plays a significant role in the observed spectra, in particular for the nitrate asymmetric band splitting and frequency shift. The spectral response from water solvation for iron and aluminum nitrates is nonlinear as compared to linear for sodium nitrate, suggesting significantly different solvation environments that are limited by water hydration capacity at higher concentrations. Moreover, a non-hydrogen bonded OH, dangling OH, from hydrating water molecules is observed spectroscopically for Al and Fe nitrate solutions. Furthermore, aluminum nitrate perturbs the surface water structure more than iron nitrate despite aluminum being a weaker Lewis acid. The surface water structure is thus found to be unique for the Al(NO3)3 solutions as compared to both Fe(NO3)3 and NaNO3, such that surface solvation is more pronounced. This observation exemplifies the nature of the Fe(III) and Al(III) ions and their substantial influence on the surface water structure.

Octave-wide broadening of ultraviolet dispersive wave driven by soliton-splitting dynamics

Coherent dispersive wave emission, as an important phenomenon of soliton dynamics, manifests itself in multiple platforms of nonlinear optics from fibre waveguides to integrated photonics. Limited by its resonance nature, efficient generation of coherent dispersive wave with ultra-broad bandwidth has, however, proved difficult to realize. Here, we unveil a new regime of soliton dynamics in which the dispersive wave emission process strongly couples with the splitting dynamics of the driving pulse. High-order dispersion and self-steepening effects, accumulated over soliton self-compression, break the system symmetry, giving rise to high-efficiency generation of coherent dispersive wave in the ultraviolet region. Simultaneously, asymmetric soliton splitting results in the appearance of a temporally-delayed ultrashort pulse with high intensity, overlapping and copropagating with the dispersive wave pulse. Intense cross-phase modulations lead to octave-wide broadening of the dispersive wave spectrum, covering 200–400 nm wavelengths. The highly-coherent, octave-wide ultraviolet spectrum, generated from the simple capillary fibre set-up, is in great demand for time-resolved spectroscopy, ultrafast electron microscopy and frequency metrology applications, and the critical role of the secondary pulse in this process reveals some new opportunities for all-optical control of versatile soliton dynamics.

Tunable spin splitting of reflected vortex-beam of Weyl semimetal metasurface with stronger optical activity

This work investigated the spin splitting of a reflected beam with a vortex beam irradiating on a metasurface. This metasurface structure is the periodically rectangular-groove array of ionic crystal, where the array is a sub-wavelength grating with its periodical direction situated in the surface plane. In the grating structure, we embedded magnetic Weyl semimetals. Consequently, a stronger optical activity can be found, which originates from the unique electronic structure of Weyl semimetals and the orientation of the grating arrangement. By controlling the separation of Weyl points and grating orientation, we observe notable asymmetric spin splitting in different frequency ranges with distinctly unique distributions. Significant spin splitting was observed to be correlated with substantial Kerr rotation angles and reflectance differences, indicating strong optical activity. Additionally, with the increasing topological charges, the spin splitting increases significantly. Our results are useful for the manipulation of infrared radiations and infrared optical detection.

Signatures of hybridization of multiple Majorana zero modes in a vortex.

Majorana zero modes (MZMs) are emergent zero-energy topological quasiparticles that are their own antiparticles1,2. Detected MZMs are spatially separated and electrically neutral, so producing hybridization between MZMs is extremely challenging in superconductors3,4. Here, we report the magnetic field response of vortex bound states in superconducting topological crystalline insulator SnTe (001) films. Several MZMs were predicted to coexist in a single vortex due to magnetic mirror symmetry. Using a scanning tunnelling microscope equipped with a three-axis vector magnet, we found that the zero-bias peak (ZBP) in a single vortex exhibits an apparent anisotropic response even though the magnetic field is weak. The ZBP can robustly extend a long distance of up to approximately 100 nm at the (001) surface when the magnetic field is parallel to the ( )-type mirror plane, otherwise it displays an asymmetric splitting. Our systematic simulations demonstrate that the anisotropic response cannot be reproduced with trivial ZBPs. Although the different MZMs cannot be directly distinguished due to the limited energy resolution in our experiments, our comparisons between experimental measurements and theoretical simulations strongly support the existence and hybridization of symmetry-protected multiple MZMs. Our work demonstrates a way to hybridize different MZMs by controlling the orientation of themagnetic field and expands the types of MZM available for tuning topological states.

Asymmetric droplet splitting in a T-junction under a pressure difference

In this paper, the phase-field multiphase lattice Boltzmann method is employed to simulate droplet breakup in a T-junction under different outlet pressures. Three behaviors of droplet breakup: non-breakup (flow pattern I), breakup with tunnels (flow pattern II), and breakup with permanent obstruction (flow pattern Ⅲ) are identified. The evolution of morphological characteristics of droplet breakup is quantitatively characterized, based on which the asymmetric splitting mechanisms and the influencing factors are clarified. Additionally, the factors influencing the droplet splitting volume ratio (VII/VI) are elucidated. The results indicate that there is a non-linear relationship between the VII/VI and the flow rate ratio. Moreover, the curve depicting the final VII/VI versus the initial droplet length exhibits a V-shape and has a minimum value. A conclusion is drawn that the Capillary number mainly influences flow pattern II, with the final VII/VI decreasing as the Capillary number increases. Additionally, for flow pattern III, the final VII/VI increases linearly with rising droplet size at low viscosity ratios, whereas it decreases linearly at high viscosity ratios. The growing outlet pressure difference enlarges the flow difference between the two branches, leading to an increase in the final VII/VI.

Unraveling the link between magma and deformation during slow seafloor spreading

Detachment faulting related to oceanic core complexes (OCCs) has been suggested to be a manifestation of slow seafloor spreading. Although numerical models suggest OCCs form under low magma supply, the specific interaction between magmatism and tectonic faulting remains elusive. This paper examines seismic observations detailing the spatiotemporal interactions between magmatism, high-angle faulting, and detachment faulting at a slow-spreading mid-ocean ridge in the West Philippine Basin. We identified a magma-rich spreading phase, indicated by a magmatic top basement and oceanic crust with shallow-penetrating high-angle normal faults. An axial valley reveals an along-strike transition from magmatically-dominated to highly tectonized oceanic crust over a distance of 70 km. Two older OCCs with concave-down fault geometries and a younger OCC with steep-dipping faulting suggest sequential detachments with the same polarity. Our findings suggest: (1) slow seafloor spreading alternates between high-angle faulting with a relatively high magma supply and detachment faulting with a limited magma supply; (2) sequential development of younger detachments in the footwall of its predecessor leads to an asymmetric split in the newly accreted crust; and (3) the life cycle of OCC ends with high-angle faults that overprint the detachment and act as magma pathways, sealing the OCC. Our study captures the dynamic interaction between high-angle and detachment faults and their concurrent and subsequent relationship to magmatic systems. This reveals that strain distribution along strike is critical to OCC formation, thus enriching our understanding beyond conventional considerations such as spreading rates and melt budgets at mid-ocean ridges.

Splitting behavior and breakup mechanism of bubbles in the split‐and‐recombine microchannel

AbstractSplit‐and‐recombine (SAR) microreactor is an advanced reactor for chemical process intensification. Bubble flow in the SAR microchannel is an important phenomenon that affects reaction efficiency, however drew little attention before. This study aims to explore the underlying mechanisms of bubble splitting, retraction, and breakup behaviors in a compact SAR microchannel. Two breakup flow patterns, unilateral flow and unilateral alternate flow were identified with symmetric or asymmetric splitting, respectively. Mechanism analysis indicates that the splitting symmetry issue is related to liquid slug size, viscous effect and novel retraction behavior of a splitting filament. The retraction is induced by the interconnection and unequal pressures between the splitting filaments. The correlation between normalized breakup time and Ca number confirms the Capillary‐pressure breakup mechanism for the splitting gas filaments. Two empirical correlations for the two breakup flow patterns were proposed, which illustrate the significant contribution of bubble retraction to the breakup degree.

Goos–Hänchen shifts on spin representation

We analyze the Goos–Hänchen (GH) shift and longitudinal spin splitting (LSS) at a planar interface between two optical media in the spin representation. While these optical effects have been studied previously, we examine the direct and cross-reflected light fields, and their interference from the spin representation to reveal the physical mechanism of the GH shift and establish a quantitative relationship between it and LSS. Furthermore, we show that angular asymmetric spin splitting occurs under the spin representation when linearly polarized light with a phase difference of 180° and an amplitude ratio angle deviating from 45° impinges on the air–glass interface at Brewster’s angle. Finally, we reveal that the spin component field of the reflected light field for the total reflection case is different from that of the Brewster angle reflection, the most typical manifestation is that the intensity of the two spin component fields is not equal.

Giant asymmetric proximity-induced spin–orbit coupling in twisted graphene/SnTe heterostructure

We analyze the spin–orbit coupling effects in a 3∘-degree twisted bilayer heterostructure made of graphene and an in-plane ferroelectric SnTe, with the goal of transferring the spin–orbit coupling from SnTe to graphene, via the proximity effect. Our results indicate that the point-symmetry breaking due to the incompatible mutual symmetry of the twisted monolayers and a strong hybridization has a massive impact on the spin splitting in graphene close to the Dirac point, with the spin splitting values greater than 20 meV. The band structure and spin expectation values of graphene close to the Dirac point can be described using a symmetry-free model, triggering different types of interaction with respect to the threefold symmetric graphene/transition-metal dichalcogenide heterostructure. We show that the strong hybridization of the Dirac cone’s right movers with the SnTe band gives rise to a large asymmetric spin splitting in the momentum space. Furthermore, we discover that the ferroelectricity-induced Rashba spin–orbit coupling in graphene is the dominant contribution to the overall Rashba field, with the effective in-plane electric field that is almost aligned with the (in-plane) ferroelectricity direction of the SnTe monolayer. We also predict an anisotropy of the in-plane spin relaxation rates. Our results demonstrate that the group-IV monochalcogenides MX (M = Sn, Ge; X = S, Se, Te) are a viable alternative to transition-metal dichalcogenides for inducing strong spin–orbit coupling in graphene.

Differences in Kondo Splitting of Surface Quantum Systems Induced by Two Distinct Magnetic Tips: A Joint Method of DFT and HEOM.

The interactions between a magnetic tip and local spin impurities initiate unconventional Kondo phenomena, such as asymmetric suppression or even splitting of the Kondo peak. However, a lack of realistic theoretical models and comprehensive explanations for this phenomenon persists due to the complexity of the interactions. This research employs a joint method of density functional theory (DFT) and hierarchical equation of motion (HEOM) to simulate and contrast the modulation of the spin state and Kondo behavior in the Fe/Cu(100) system with two distinct magnetic tips. A cobalt tip, possessing a larger magnetic moment, incites greater atomic displacement of the iron atom, more notable alterations in electronic structure, and enhanced charge transfer with the environment compared with the control process utilizing a nickel tip. Furthermore, the Kondo resonance undergoes asymmetric splitting as a result of the ferromagnetic correlation between the iron atom and the magnetic tip. The Co tip's higher spin polarization results in a wider spacing between the splitting peaks. This investigation underscores the precision of the DFT + HEOM approach in predicting complex quantum phenomena and explaining the underlying physical principles. This provides valuable theoretical support for developing more sophisticated quantum regulation experiments.

Tunable spatial and angular spin splitting of reflected vortex-beam off hyperbolic metasurface

This paper investigated the spin splitting of the reflected beam with a vortex beam irradiating on a hyperbolic metasurface. This metasurface structure is the periodically rectangular-groove array on the surface of a hyperbolic crystal with the optical axis normal to its surface, where the array is a sub-wavelength biaxially hyperbolic grating with its periodical direction situated in the surface plane. Based on the hexagonal nitride boron crystal, we theoretically and numerically analyzed the spatial and angular spin splittings of the reflected beam, containing those produced by the transverse and longitudinal shifts. We found that the spatial shifts or spin splitting can be obtained in the first-order approximation of beam deflection, but the angular shifts can be described in the second-order approximation so that it enormously varies with the beam waist. Due to the hyperbolic anisotropy of the metasurface and the intrinsic orbital angular momentum in the incident beam, the expressions of spatial and angular shifts are effectively modified, and a unique double reflection effect occurs on the surface. Near certain reflective intensity distribution singularities, extremely asymmetrical spin splitting can be observed. These shifts and spin splitting can be tuned by varying the orientation of the incident plane and the angle of incidence.

Vortex splitting in two-dimensional fluids and non-neutral electron plasmas with smooth vorticity profiles

Initially, elliptical, quasi-two-dimensional (2D) fluid vortices can split into multiple pieces if the aspect ratio is sufficiently large due to the growth and saturation of perturbations known as Love modes on the vortex edge. Presented here are experiments and numerical simulations, showing that the aspect ratio threshold for vortex splitting is significantly higher for vortices with realistic, smooth edges than that predicted by a simple “vortex patch” model, where the vorticity is treated as piecewise constant inside a deformable boundary. The experiments are conducted by exploiting the E × B drift dynamics of collisionless, pure electron plasmas in a Penning–Malmberg trap, which closely model 2D vortex dynamics due to an isomorphism between the Drift–Poisson equations describing the plasmas and the Euler equations describing ideal fluids. The simulations use a particle-in-cell method to model the evolution of a set of point vortices. The aspect ratio splitting threshold ranges up to about twice as large as the vortex patch prediction and depends on the edge vorticity gradient. This is thought to be due to spatial Landau damping, which decreases the vortex aspect ratio over time and, thus, stabilizes the Love modes. Near the threshold, asymmetric splitting events are observed in which one of the split products contains much less circulation than the other. These results are relevant to a wide range of quasi-2D fluid systems, including geophysical fluids, astrophysical disks, and drift-wave eddies in tokamak plasmas.

Active manipulation of the plasmonic induced asymmetric photonic spin Hall effect

The asymmetric photonic spin Hall effect (APSHE) induced by surface plasmon polaritons in a graphene-based structure is actively manipulated by external magnetic field and electric field. It is revealed that the spin-dependent splitting exhibits spatio-temporal asymmetric property due to the involvement of the anisotropic graphene. The peak of asymmetry degree in APSHE at the position of reflectance valley corresponds toward a smaller incident angle with the increase of magnetic field intensity or Fermi energy, which is attributed to the tunability of reflectance for the graphene-based structure. Based on the asymmetric splitting shift, a potential application is proposed for detecting low concentration gas molecules and the detection resolution can be dynamically tunable by changing the magnetic field intensity and Fermi energy. This study may provide a new reference in the fabrication of graphene-based plasmonic sensor devices.

Asymmetric acoustic splitting with the dual-layers of binary metagratings

Here, we exhibit the asymmetric acoustic splitting with the dual-layers of binary metagratings (BMs), i.e., BM1 and BM2. For the positive incidence (PI) normally from the BM1 side, acoustic waves are freely transmitted through the BM1 and split into two beams with the transmitted angles at and , then the two beams are freely transmitted through the BM2 with the transmitted angles at and . For the negative incidence (NI) normally from the BM2 side, acoustic waves are wholly reflected. Hence, the asymmetric acoustic splitting is observed. Here, the dual-layers of BMs are exemplified by the coating cells with different period lengths. Excellent agreement can be observed between the numerical simulations and the theoretical analysis. Our proposal may be applied in noise control and acoustic communication.

Acoustic Bilayer Gradient Metasurfaces for Perfect and Asymmetric Beam Splitting

We experimentally and theoretically present a paradigm for the accurate bilayer design of gradient metasurfaces for wave beam manipulation, producing an extremely asymmetric splitting effect by simply tailoring the interlayer size. This concept arises from anomalous diffraction in phase gradient metasurfaces and the precise combination of the phase gradient in bilayer metasurfaces. Ensured by different diffraction routes in momentum space for incident beams from opposite directions, extremely asymmetric acoustic beam splitting can be generated in a robust way, as demonstrated in experiments through a designed bilayer system. Our work provides a novel approach and feasible platform for designing tunable devices to control wave propagation.

Acidity Quantification and Structure Analysis of Amide-AlCl3 Liquid Coordination Complexes for C4 Alkylation Catalysis

Liquid coordination complexes (LCCs), which are formed between metal halides and donor molecules, represent promising catalysts. Six amide-AlCl3 LCCs were successfully synthesized, followed by their characterization through NMR, Raman, and UV-visible spectroscopy. The acidity of these LCCs was quantified by performing computational modelling of fluoride ion affinities (FIA) and experimental Gutmann–Beckett measurements. Spectroscopic analysis indicated bidentate coordination between amide ligands and Al, which induced asymmetric splitting of Al2Cl6 into diverse ions such as [AlCl2L2]+, [AlCl4]−, [AlCl3L], and [Al2Cl6L]. The computed FIA was found to align well with the experimental acidity trends, thereby confirming the proposed structure of the LCC. In the alkylation tests, the LCC with a high acidity demonstrated an increase in the yields of C5-C7 alkylates. These results provide an in-depth understanding of the tuneable structures of amide-AlCl3 LCCs. The acidity of LCCs can be controlled by tuning the ratio of the organic ligand to AlCl3, which allows bidentate coordination to facilitate asymmetric splitting of Al2Cl6. The LCCs demonstrate a high degree of potential as versatile and sustainable acid catalysts in alkylation reactions. These findings may advance the foundational knowledge of LCCs for the purpose of targeted acid catalyst design.

CASSR based metamaterial tunable low pass filter

With the need for compact, discrete, and tunable passive devices in the upcoming wireless communication techniques, metamaterials have been proven to their incredible properties and have raised a new paradigm. The article discusses the possibility to design an electrically small metamaterial low pass filter (LPF) from a Complementary Asymmetric Single Split Resonator (CASSR) with a tunable pass-band for high-performance communication systems. The proposed CASSR filter on low-cost FR4 substrate of relative permittivity 4.4 and thickness 1.6 mm for a cut-off frequency of 1.12 GHz shows a roll-off rate of 159 dB/GHz. It is electrically small with a footprint area of 0.112λ × 0.112λ mm2 with ka = 0.70.

Fe-induced Kondo peak splitting in tip-functionalized scanning tunneling spectroscopy: A first-principles-based simulation

The spin-polarized scanning tunneling microscope (SP-STM) has been employed to enhance its capabilities of detecting the electronic and magnetic properties of organometallic molecules. Using a tip functionalized with a cobaltocene (Cc) molecule, recent SP-STM experiment performed on the Cu-tip/Cc/Fe/Cu(100) composite junction revealed an asymmetric Kondo resonance splitting in the differential conductance (dI/dV) spectrum. However, a systematic theoretical simulation of such system is lacking, and the important roles of the substrate spin-polarization and the Fe adatom still remain to be elucidated. In this work, by combining density functional theory and the hierarchical equations of motion methods, we achieve first-principles-based simulations of the tip control process of the Cu-tip/Cc/Fe/Cu(100) junction. We correctly reproduce the experimental results and demonstrate the influences of the Fe adatom on the spin-polarization of the substrate and on the Kondo resonance splitting in the dI/dV spectra.

Deformed shell stabilities influencing the fragment formation in sub-lead nuclei

The fragment mass distributions from fission in the sub-lead nuclei gave traces of the co-existence of symmetric and asymmetric fission modes. To investigate the major drivers behind the observed asymmetry, we have accumulated the fission data of 19 neutron-deficient lead island nuclei from the last few years and compared them with the corresponding predictions made by the GEF (General description of fission observables) model. Consequently, both experimental and theoretical analysis performed to extract asymmetric fission properties led to similar results, showing the deformed proton shell gaps, at Z = 34 for light fragments and Z = 42, 44, and 46 for heavier fragments, associated with large quadrupole deformations as the possible origin for the asymmetric split for all isotopes ranging from 178−198Hg, 176−186Pt, and 179−191Au. These observations contradicted the earlier theoretical report where neutron numbers were declared to play a leading role in deciding asymmetric fission. This disagreement motivated us to get better insight by extending the examination over a large domain around Pb covering Hg, Pt, Au, Pb, and Po nuclides. Although protons in the light fragments are still spotted to be constant and influenced by the deformed shell gaps at Z = 34, protons in the heavier fragments are found increasing with rising ZCN and gave evidence of negligible influence from Z = 42, 44, and 46 shell gaps. Interestingly, the excellent compatibility of GEF results with the experimental outcomes proved it an efficient model for extracting fragment properties. However, it could only reproduce the experimental symmetric fission fraction (SFF) within the 30–52 MeV energy window. The GEF's inadequate predictability of the multichance fission contributions might be considered as one of the possible reasons behind the observed disagreements between the GEF and experimental SFF above 52 MeV. Moreover, the other reason might be the inadequate modeling of the evolution of the fission fragment mass/charge distribution with excitation energy.

Asymmetric branch selection and splitting of droplets in T-junction microchannels

The droplet motion in the T-junction is the basis for the design of droplet microfluidic chip. This paper investigates droplet motion in T-junction microchannels based on experiments and simulations to analyze the droplet motion mode and its effect on the downstream flow of the channel. The droplet motion can be divided into three modes, including flowing into the downstream main channel, flowing into the side branch, and splitting, whose transitions depend on the inlet flow ratio and droplet length. The critical droplet length, to determine whether the droplet is complete through the junction, follows a non-linear relationship of capillary number with the coefficient of 0.3–0.5, which is influenced by the liquid viscosity ratio. It was found that the droplets can be divided into two kinds according to its length by l0 = 0.8wm, which have significantly different interfacial deformations and cause various fluctuations of the branch flow even under the same flow conditions.