Wave Vector Research Articles

Hybrid strategy in compact tailoring of multiple degrees-of-freedom toward high-dimensional photonics

Abstract Tailoring multiple degrees-of-freedom (DoFs) to achieve high-dimensional laser field is crucial for advancing optical technologies. While recent advancements have demonstrated the ability to manipulate a limited number of DoFs, most existing methods rely on bulky optical components or intricate systems that employ time-consuming iterative methods and, most critically, the on-demand tailoring of multiple DoFs simultaneously through a compact, single element—remains underexplored. In this study, we propose an intelligent hybrid strategy that enables the simultaneous and customizable manipulation of six DoFs: wave vector, initial phase, spatial mode, amplitude, orbital angular momentum (OAM) and spin angular momentum (SAM). Our approach advances in phase-only property, which facilitates tailoring strategy experimentally demonstrated on a compact metasurface. A fabricated sample is tailored to realize arbitrary manipulation across six DoFs, constructing a 288-dimensional space. Notably, since the OAM eigenstates constitute an infinite dimensional Hilbert space, this proposal can be further extended to even higher dimensions. Proof-of-principle experiments confirm the effectiveness in manipulation capability and dimensionality. We envision that this powerful tailoring ability offers immense potential for multifunctional photonic devices across both classical and quantum scenarios and such compactness extending the dimensional capabilities for integration on-chip requirements.

3D-printed fiber-based perfect vortex beam generator.

An all-fiber focused perfect vortex beam (PVB) generator is reported and fabricated by using 3D printing technology. The generator is constructed by integrating a designed spiral axicon zone plate (SAZP) on the fiber-end facet. The ring diameters of the generated beams are independent of the topological charges and positively correlated with the wave vectors in the transverse direction. By controlling the axicon angle, the ring diameter can be freely adjusted. The experimental results are consistent with the simulation results, confirming the rationality of the design. These generated PVBs are expected to be useful in applications such as high-capacity fiber-optic communication and multifunctional optical tweezers.

OutExaRD: Enhancing Resource Discovery for Support Dynamic and Interactive Events on Out-of-Distributed Exascale Systems

This study investigates the influence of dynamic and interactive events on the functionality of resource discovery within distributed Exascale systems. These events significantly impact resource discovery both before and after their occurrence. However, effectively analyzing these impacts is challenging due to the lack of a direct connection to the activator of resource discovery functionality. To address this challenge, we propose an innovative mechanism that establishes a connection structure defined by a wave vector, linking resource discovery functionality to its activator. This wave vector model is crucial in shaping resource discovery operations. It implements a searching system designed to create spatial dimensions, allowing resource discovery functionality to evaluate the impact of events on spatial generation within each searching system. This methodology facilitates a more effective analysis of events’ roles in managing their effects while minimizing disruption to system elements. Our research results demonstrate the efficacy of our approach, revealing that the wave vector model positively influenced resource discovery functionality in an impressive 93% of dynamic and interactive events, thereby optimizing the execution of resource discovery activities. This high success rate provides reassurance about the reliability of our approach.

Influence of Magnetic Anisotropy on the Ground State of [CH3NH3]Fe(HCOO)3: Insights into the Improper Modulated Magnetic Structure.

The hybrid perovskites [CH3NH3]CoxNix-1(HCOO)3 with x = 0, 0.25, 0.5, 0.75, and 1.0 possess multiple phase transitions, including incommensurate structures. Notably, [CH3NH3]Ni(HCOO)3 features a proper magnetically incommensurate structure ground state. To explore similar behavior, we investigated the isomorphous [CH3NH3]Fe(HCOO)3 (1). A combination of magnetometry measurements, single crystal and powder neutron diffraction, and density functional theory calculations have been used to accurately determine and understand the sequence of nuclear and magnetic phases present in compound 1. At room temperature, it crystallizes in the Pnma space group with a perovskite structure. Below 170 K, new satellite reflections indicate a transition to a modulated structure, refined in the Pnma(00γ)0s0 with q1 = 0.1662(2)c*. At 75 K, the satellite reflections become closer to the main reflections, indicating a second transition, which maintains the superspace group symmetry but decreases the modulation wave vector to q2 = 0.1425(2)c*, i.e., with a longer modulation period. This modulation persists to 2 K, overlapping with the onset of 3D antiferromagnetic order at 17 K, offering a unique opportunity to study magneto-structural coupling. Our results point to an improper magnetic modulated structure where, interestingly, the spins are perpendicular to those of previously reported compounds.

Current Control of Spin Helicity and Nonreciprocal Charge Transport in a Multiferroic Conductor

AbstractA multiferroic state with both electronic polarity (P) and magnetization (M) shows the inherently strong P‐M coupling when P is induced by cycloidal (Néel‐wall like) spin modulation. The sign of P is determined by the clockwise or counterclockwise rotation of spin, termed the spin helicity. Such a multiferroic state is not limited to magnetic insulators but can be broadly observed in conductors. Here, the current control of the multiferroics is reported in a helimagnetic metal YMn6Sn6 and its detection through nonreciprocal resistivity (NRR). The underlying concept is the coupling of the current with the toroidal moment as well as with the magneto‐chirality χv · M, where and χv are the unit modulation wave vector and the vector spin chirality, respectively. An enhancement of NRR is furthermore observed by the spin‐cluster scattering via χv and its fluctuation. These findings may pave the way to an exploration of multiferroic conductors and the application of the spin‐helicity degree of freedom as a state variable.

Topological Defect Mediated Helical Phase Reorientation by Uniaxial Stress.

Strain engineering enables precise, energy-efficient control of nanoscale magnetism. However, unlike well-studied strain-dislocation interactions in mechanical deformation, the spatial evolution of strain-induced spin rearrangement remains poorly understood. Using insitu Lorentz transmission electron microscopy, we manipulate and observe helical domain reorientation under quantitatively applied uniaxial tensile stress. Our findings reveal striking similarity to plastic deformation in metals, where the critical stress for propagation vector (Q) reorientation depends on its angle with the stress direction. Magnetic defects mediate reorientation via "break-and-reconnect" or "dislocation gliding-annihilation" processes. Simulations confirm that strain-induced anisotropic Dzyaloshinskii-Moriya interaction may play a key role. These insights advance strain-driven magnetism and offer a promising route for energy-efficient magnetic nanophase control in next-generation information technology.

Parametric Study of Asymmetric Propagation of Guided and Unguided EMIC Waves Near the Local Characteristic Frequencies

AbstractPrevious studies demonstrate that the propagation of the guided and unguided electromagnetic ion cyclotron (EMIC) waves near the local characteristic frequencies in a dipole field shows prominent asymmetry with the wave vector pointing toward lower L shells (wave normal angle ) and higher L shells () at low magnetic latitudes () using representative cases. The and dependence of this asymmetric behavior and the role of magnetic gradients in this process are not clear. Using full‐wave simulations and ray theories, a parametric study is conducted to address these questions. We find that the refraction due to the magnetic gradient term can be quantified by (the variation of during the wavelength) primarily contributed by the product of the normalized derivative of the refractive index, the magnetic gradient and the unit vector perpendicular to . At low , the sign of generally remains constant and is large so that with keeps deviating from the field line while with has the potential to be close to the field line. This explains that the guided left‐handedly polarized (LHP) EMIC wave with may reverse its polarization and propagates to much lower altitudes if is within certain angular window. This also explains the for the maximum coupling efficiency from the unguided to guided LHP EMIC mode can be tens of degrees away from the field‐aligned direction. As increases, the asymmetry of and the propagation of EMIC waves near the local characteristic frequencies becomes smaller.

Partially Coherent Twisted States in Two-Dimensional Arrays of Phase Oscillators: Interplay of Nonlocal Coupling and Heterogeneity

We consider an infinitely large two-dimensional array of nonlocally coupled phase oscillators with a Lorentzian distribution of natural frequencies. The simplest dynamical regimes supported by such a system are a completely disordered state (or uniform incoherence) and partially coherent twisted states, which are characterized by a linear increase in phase with distance along some direction. In the continuum limit, the coarse-grained dynamics of these regimes is described by an integro-differential equation derived from the Ott–Antonsen theory. In particular, partially coherent twisted states correspond to plane wave solutions of this equation. We perform a linear stability analysis of these waves, derive an explicit long-wave instability criterion for them, and analyze it. This allows us to find how stable twisted states with different wave vectors appear and change for increasing heterogeneity in the original oscillator system. The obtained analytical results are illustrated by their application to three specific types of radially symmetric nonlocal coupling.

Emergence of a metallic surface state for narrow bandgap Mott insulator Sr3Ir2O7(001) thin films

We report evidence of a finite density of states at the Fermi level at the surface of epitaxial thin films of the narrow bandgap Mott insulator Sr3Ir2O7(001). The Brillouin zone critical points for Sr3Ir2O7(001) thin films have been determined by a comparison of the band mapping from angle-resolved photoemission spectroscopy and low energy electron diffraction. Angle-resolved x-ray photoemission studies reveal the surface termination of Sr3Ir2O7(001) is Sr-O. The absence of dispersion with photon energy, or changing wave vector along the surface normal, indicates the two-dimensional character of the bands contributing to the density of states close to the Fermi level for Sr3Ir2O7(001) thin films. Thus, the finite density of states at the Fermi level is attributed to surface states or surface resonances. The appearance of a finite density of states at the Fermi level is consistent with the increased conductivity with decreasing film thickness for ultrathin Sr3Ir2O7(001) films.

Length-scale dependence of Stokes-Einstein breakdown in active glass-forming liquids.

The Stokes-Einstein (SE) relation, which relates diffusion constants with the viscosity of a liquid at high temperatures in equilibrium, is violated in the supercooled temperature regime. Whether this relation is obeyed in nonequilibrium active liquids is a question of significant current interest to the statistical physics community trying to develop the theoretical framework of nonequilibrium statistical mechanics. Via extensive computer simulations of model active glass-forming liquids in three dimensions, we show that SE is obeyed at a high temperature similar to the equilibrium behavior, and it gets violated in the supercooled temperature regimes. The degree of violation increases systematically with the increasing activity which quantifies the amount the system is driven out of equilibrium. First passage-time (FPT) distributions helped us to gain insights into this enhanced breakdown from the increased short-time peak, depicting hoppers. Subsequently, we study the wave vector dependence of SE relation and show that it gets restored at a wave vector that decreases with increasing activity, and the crossover wave vector is found to be proportional to the inverse of the dynamical heterogeneity length scale in the system. Our work showed how SE violation in active supercooled liquids could be rationalized using the growth of dynamic length scale, which is found to grow enormously with increasing activity in these systems.

Machine learning-powered data cleaning for LEGEND: a semi-supervised approach using affinity propagation and support vector machines

Machine learning-powered data cleaning for LEGEND: a semi-supervised approach using affinity propagation and support vector machines

Observation of the spiral spin liquid in a triangular-lattice material

The spiral spin liquid (SSL) is a highly degenerate state characterized by a continuous contour or surface in reciprocal space spanned by a spiral propagation vector. Although the SSL state has been predicted in a number of various theoretical models, very few materials are so far experimentally identified to host such a state. Via combined single-crystal wide-angle and small-angle neutron scattering, we report observation of the SSL in the quasi-two-dimensional delafossite-like AgCrSe2. We show that it is a very close realization of the ideal Heisenberg J1–J2–J3 frustrated model on the triangular lattice. By supplementing our experimental results with microscopic spin-dynamics simulations, we demonstrate how such exotic magnetic states are driven by thermal fluctuations and exchange frustration.

Photo-modulated magnetoresistance in a ferromagnetic/normal/ferromagnetic tunnel junction based on monolayer black phosphorene

We use the Floquet theory and the Landauer-Büttiker formula to investigate the transport characteristics of a ferromagnetic/normal/ferromagnetic tunnel junction based on monolayer black phosphorene under an off-resonant circularly polarized light (CPL). The results show that the CPL can control the transmission spectrum. In fact, the transmission gap of the antiparallel magnetized configuration is significantly broadened, and the electron blocking effect is enhanced. The transmission of the parallel magnetized configuration shows significant anisotropy and strong wave vector filtering effect. We also demonstrate that the CPL enhances the difference between the conductance of the parallel and antiparallel magnetized configurations, which in turn leads to a significant increase in tunneling magnetoresistance (TMR), even reaching TMR = 1. In particular, under the combined action of polarized light and gate voltage, the TMR in the conduction band region increases, while the TMR in the valence band region decreases. Our results will contribute to the development of optically controllable TMR devices.

Ordering of Interstitial Iron Atoms and Local Structural Distortion Induced by Iron Polycomplex in Fe1+yTe1-xSex as Seen via Transmission Electron Microscopy.

The microscopic crystalline structure of materials is widely recognized as having a profound impact on their functional properties and application potential. Alterations to the lattice often provide distinctive opportunities to finely tune specific properties, particularly in strongly correlated systems. A paradigmatic case is the iron-based high-temperature superconductors, where the microstructure plays an important role in modulating superconductivity. In this work, aberration-corrected scanning transmission electron microscopy (STEM) is employed to investigate the microstructure and intrinsic chemical heterogeneity of Fe1+yTe, Fe1+yTe0.8Se0.2, and Fe1+yTe0.5Se0.5. A previously unforeseen superstructure phase, characterized by a wave vector q = (0.4, 0, 0.5), arising from the ordered arrangement of interstitial iron atoms, is clearly visible in the parent compound Fe1+yTe. Under these specific structural conditions, interstitial iron atoms interact with adjacent Fe atoms, forming iron polycomplexes that induce pronounced distortions in the FeTe4 tetrahedra and may potentially foster the emergence of ferromagnetic clusters. The experimental findings further illustrate that appropriate Se substitution effectively suppresses interstitial iron concentration and ordering, with Fe1+yTe0.5Se0.5 notably exhibiting the lowest concentration. The observations also suggest that Se substitution occurs randomly and Te/Se-induced nanoscale phase separation, driven by chemical heterogeneity is commonly observed within Fe1+yTe1-xSex crystals.

Evolution of weak, homogeneous turbulence subject to rotation and stratification: Comparable wave and nonpropagating components.

Following on from previous work [J. F. Scott and C. Cambon, J. Fluid Mech. 979, A17 (2024)10.1017/jfm.2023.1046], this article concerns weak (small Rossby or Froude number), homogeneous turbulence subject to rotation and stable stratification. The flow is expressed as a combination of particular solutions (modes) of the linearized governing equations without viscosity or diffusion. Modes are of two types: oscillatory ones which represent inertial-gravity waves and time-independent ones that express a nonpropagating (NP) component of the flow. It was shown in the previous work that, at leading order, the NP component evolves independently of the wave component and a specifically adapted direct numerical simulation (DNS) approach was introduced to describe the NP component, the same approach which is employed here. Using wave-turbulence analysis and assuming the NP amplitude is small compared with the wave amplitude, evolution equations for the wave spectra were derived and numerically exploited. Here, those equations are extended to the case when the NP and wave components are of comparable magnitude. The NP spectra then appear in the wave-turbulence equations, which means those equations are no longer closed. As a result, a combination of adapted DNS for the NP component and the wave-turbulence equations is used and numerical solutions of the latter are given. Terms in the wave-turbulence equations arising from the NP component couple pairs of wave modes, adding to the three-wave interactions of the previous work when the latter exist. This is found to considerably increase the wave dissipation. Indeed, it provides the only mechanism for significant dissipation in the cases for which three-wave interactions are absent. The additional dissipation is especially important for wave modes having wave vectors perpendicular to the vertical or rotation axis, but is also effective for other directions.

Observation of a Giant Goos-Hänchen Shift for Matter Waves.

The Goos-Hänchen (GH) shift describes a phenomenon in which a specularly reflected beam is translated along the reflecting surface such that the incident and reflected rays no longer intersect at the surface. Using a neutron spin-echo technique and a specially designed magnetic multilayer mirror, we have measured the relative phase between the reflected up and down neutron spin states in total reflection. The relative GH shift calculated from this phase shows a strong resonant enhancement at a particular incident neutron wave vector, which is due to a waveguiding effect in one of the magnetic layers. Calculations based on the observed phase difference between the neutron states indicate a propagation distance along the waveguide layer of 0.65mm for the spin-down state, which we identify with the magnitude of the giant GH shift. The existence of a physical GH shift is confirmed by the observation of neutron absorption in the waveguide layer. We propose ways in which our experimental method may be exploited for neutron quantum-enhanced sensing of thin magnetic layers.

Interaction between Charge Density Waves in the Monoclinic Phase of NbS3

In the monoclinic polytype NbS3-II, the monoclinic b-axis of which coincides with the direction of greatest conductivity, two charge density waves (CDWs) have been observed at room temperature: CDW-0 with the wave vector q 0 = 0.5a* + 0.352b* + 0.5c* and CDW-1 with the wave vector q 1 = 0.5a* + 0.298b* + 0.5c*. X‑ray diffraction patterns obtained in the temperature range of 90–500 K have shown that the vectors q 0 and q 1 depend on the temperature, but their b* coordinates satisfy the relation $$2q_{0}^{{{\mathbf{b}}\text{*}}}(T) + q_{1}^{{{\mathbf{b}}\text{*}}}(T) = {\text{const}} = 1$$ . It has been concluded that the wave vector q 1 of CDW-1 is determined not only by the nesting of Fermi surfaces, but also by the vector q 0, because CDW-1 is adjusted to the second harmonic of CDW-0, which indicates the interaction between charge density waves. This conclusion has been confirmed by structural studies of NbS3-II samples, the lattice of which is strongly deformed due to a high concentration of twins. In these samples, CDW-0 is conserved, and the wave vector of CDW-1 has the b* component not related to q 0.

Effect of volume fractional change of nanoparticles on surface plasmon polariton

The dispersion relation of surface plasmon polaritons (SPPs) is investigated as a function of the volume fraction of silver nanoparticles at the interface between nanocomposite and atomic media. The increase in silver nanoparticle content significantly influences SPP propagation, which is crucial for advancing plasmonic technologies. As the volume fraction of silver nanoparticles increases from 0% to 60%, the real part of the SPP wave vector rises from to , and the SPP wavelength decreases from to . This also modifies the propagation length from to and reduces the penetration depth in the nanocomposite from 0.125 nm to 0.005 nm.

Extreme wave skewing and dispersion spectra of anisotropic elastic plates

Guided wave dispersion is commonly assessed by Fourier analysis of the field along a line, resulting in frequency-wave-number dispersion curves. In anisotropic plates, a point source can generate multiple dispersion branches pertaining to the same modal surface, which arise due to the angle between the power flux and the wave vector. We show that this phenomenon is very particular near zero-group-velocity points and occurs in all directions independent of the degree of anisotropy. Stationary phase points accurately describe measurements on a monocrystalline silicon plate. Published by the American Physical Society 2025

Constructive fermionic matrix product states for projected Fermi sea

Projected wave functions offer a means of incorporating local correlation effects in gapless electronic phases of matter, like metals. Although such wave functions can be readily specified formally, computing their associated physical observables is challenging. Tensor network approaches offer a modern numerical method for this task. In this paper, we develop and demonstrate a constructive tensor-network approach for obtaining physical quantities, like fermion two-point functions and density-density correlation functions, for one-dimensional projected Fermi sea states. We benchmark our method against exact analytical results for spin-1/2 electrons subjected to the Gutzwiller projection, and then present results on spinless fermions with nearest-neighbor repulsion. For a state with two pairs of Fermi points, we reveal a correlation-dependent tuning of the characteristic wave vector of the charge density modulation in the system. Published by the American Physical Society 2025