Multipole Effects Research Articles

Theory of Magnetoacoustic Resonance to Probe Multipole Effects Due to a Crystal Field Quartet

Theory of Magnetoacoustic Resonance to Probe Multipole Effects Due to a Crystal Field Quartet

Luminescence and dosimetry investigations of Eu(III) doped Ca2CeVO6 novel double perovskite

A novel composition of vanadate double perovskite Ca2CeVO6 doped with Eu3+ was successfully synthesized using combustion synthesis, wherein the doping levels of Eu3+ ranged from 1 to 6 mol%. The Rietveld refinement of the powder X-ray diffraction (XRD) data confirmed the orthorhombic structure of the phosphors. Scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX) were employed to investigate the surface morphology and elemental distribution in the phosphor, respectively. Under the excitation at 280 nm and 467 nm, the phosphor exhibited strong down-conversion red photoluminescence (PL) emission, attributed to Eu3+ transitions (5D0-7FJ, where J = 0–3) originating from its 4f states. The intensity of PL emission shows increasing trend with increasing doping concentration. However, exceeding the threshold doping concentrations led reduction in PL intensity due to multipolar interaction effects. Additionally, the Eu3+ doped Ca2CeVO6 phosphors were subjected to irradiation with a radioactive 90Sr/90Y beta source to explore their thermoluminescence (TL) properties. Post-irradiation, the phosphors displayed prominent TL glow curves, with the most intense peak at around 94 °C, followed by peaks at 160 °C and 288 °C. The TL intensity of these peaks exhibited a linear dose response within the dose range of 1 Gy–50 Gy. Besides, the TL fading and reproducibility tests showed satisfactory results. Furthermore, Tmax-Tstop experiments revealed the presence of three trap centres within the trap depth range of 0.7–2.1 eV in the Ca2CeVO6:Eu3+ phosphor. Additionally, the glow curve deconvolution (GCD) was employed to determine trapping parameters, providing valuable insights into the TL behaviour of the phosphor. Overall, the results suggest that the novel phosphor under study holds promise for its applications in lighting devices and TL dosimetry (TLD).

Research on the influence mechanism of harmonic components on the noise distribution characteristics of converter transformers

In order to elucidate the sound source characteristics during the noise propagation process of converter transformers, a series of experimental studies were conducted based on finite element simulation and proportional prototype design of converter transformers. It was found that it was unreasonable to equate converter transformers with point sound sources in previous studies. On the contrary, it should be divided into dipole and multipole distribution characteristics. Meanwhile, research has found that the noise distribution of converter transformers exhibits dipole and dipole distribution characteristics under power frequency and harmonic excitation, respectively. The contribution of harmonic components at different frequencies in the formation process of bipolar sound sources was quantified through simulation and experiments, and the key harmonic frequencies for forming multipole sound sources were determined as paired combinations of 5, 7, 11, 13, 23, and 25. Based on the above research conclusions, a noise reduction approach for converter transformers based on bipolar and multipole boundary effects is proposed.

Experimental Evidence for a Berry Curvature Quadrupole in an Antiferromagnet

Berry curvature multipoles appearing in topological quantum materials have recently attracted much attention. Their presence can manifest in novel phenomena, such as nonlinear anomalous Hall effects (NLAHE). The notion of Berry curvature multipoles extends our understanding of Berry curvature effects on the material properties. Hence, research on this subject is of fundamental importance and may also enable future applications in energy harvesting and high-frequency technology. It was shown that a Berry curvature dipole can give rise to a second-order NLAHE in materials of low crystalline symmetry. Here, we demonstrate a fundamentally new mechanism for Berry curvature multipoles in antiferromagnets that are supported by the underlying magnetic symmetries. Carrying out electric transport measurements on the kagome antiferromagnet FeSn, we observe a third-order NLAHE, which appears as a transverse voltage response at the third harmonic frequency when a longitudinal ac drive is applied. Interestingly, this NLAHE is strongest at and above room temperature. We combine these measurements with a scaling law analysis, a symmetry analysis, model calculations, first-principle calculations, and magnetic Monte Carlo simulations to show that the observed NLAHE is induced by a Berry curvature quadrupole appearing in the spin-canted state of FeSn. At a practical level, our study establishes NLAHE as a sensitive probe of antiferromagnetic phase transitions in other materials—such as moiré superlattices, two-dimensional van der Waal magnets, and quantum spin liquid candidates, which remain poorly understood to date. More broadly, Berry curvature multipole effects are predicted to exist for 90 magnetic point groups. Hence, our work opens a new research area to study a variety of topological magnetic materials through nonlinear measurement protocols. Published by the American Physical Society 2024

High-efficiency electromagnetic shielding based on multipolar effect in RGO/MXene aerogels decorated with ordered Fe3O4 cluster

With the widespread use of digital systems and electronic communication devices, there is an urgent need to develop lightweight and efficient electromagnetic interference (EMI) shielding materials to address the growing problem of radiation pollution. RGO/MXene/Fe3O4 aerogels were successfully designed and synthesised using a one-step hydrothermal process induced by an external magnetic field in this study. Reduced graphene RGO, MXene nanosheets and Fe3O4 nanoparticles were suitably assembled together to achieve the combined advantages. The aerogels exhibited large specific surface area and hierarchical porosity. The material not only achieves an effective synergy between magnetic loss and dielectric loss, but also exhibits satisfactory EMI shielding performance. Magnetic field induced RGO/MXene/Fe3O4 aerogels (MIRMFE-2) exhibits the best EMI shielding performance with an average SET value of 76.9 dB. The excellent shielding performance of MIRMFE is attributed to both its 3D porous structure and the high dielectric loss due to multiple polarization relaxation, magnetic loss due to eddy current loss and natural resonance. The synthesis of MIRMFE provides an effective method for, designing high-performance and lightweight EMI shielding materials.

Multipolar Conjugated Polymer Framework Derived Ionic Sieves via Electronic Modulation for Long-Life All-Solid-State Li Batteries.

Here, we build a tunable multipolar conjugated polymer framework platform via pore wall chemistry to probe the role of electronic structure engineering in improving the Li+ conduction by theoretical studies. Guided by theoretical prediction, we develop a new cyano-vinylene-linked multipolar polymer framework namely CNF-COF, which can act as efficient ion sieves to modify solid polymer electrolytes to simultaneously tune Li+ migration and stable Li anodes for long-lifespan all-solid-state (ASS) Li metal batteries at high rate. The dual-decoration of cyano and fluorine groups in CNF-COF favorably regulates electronic structure via multipolar donor-acceptor electronic effects to afford proper energy band structure and abundant electron-rich sites for enhanced oxidative stability, facilitated ion-pair dissociation and suppressed anion movements. Thus, the CNF-COF incorporation into poly (ethylene oxide) (PEO) electrolytes not only renders fast selective Li+ transport but also facilitates the Li dendrite suppression. Specifically, the constructed PEO composite electrolyte with an ultra-low CNF-COF content of only 0.5 wt % is endowed with a wide electrochemical window, a high ionic conductivity of 0.634 mS cm-1 at 60 °C and a large Li+ transference number of 0.81-remarkably outperforming CNF-COF-free counterparts (0.183 mS cm-1 and 0.22). As such, the Li symmetric cell delivers stable Li plating/stripping over 1400 h at 0.1 mA cm-2. Impressively, by coupling with LiFePO4 (LFP) cathodes, the assembled ASS Li battery under 60 °C allows for stable cycling over 2000 cycles at 1 C and over 1000 cycles even at 2 C with a large capacity retention of ~75 %, surpassing most reported ASS Li batteries using PEO-based electrolytes.

Quantum Drude oscillators coupled with Coulomb potential as an efficient model for bonded and non-covalent interactions in atomic dimers.

The quantum Drude oscillator (QDO) model has been widely used as an efficient surrogate to describe the electric response properties of matter as well as long-range interactions in molecules and materials. Most commonly, QDOs are coupled within the dipole approximation so that the Hamiltonian can be exactly diagonalized, which forms the basis for the many-body dispersion method [Phys. Rev. Lett. 108, 236402 (2012)]. The dipole coupling is efficient and allows us to study non-covalent many-body effects in systems with thousands of atoms. However, there are two limitations: (i) the need to regularize the interaction at short distances with empirical damping functions and (ii) the lack of multipolar effects in the coupling potential. In this work, we convincingly address both limitations of the dipole-coupled QDO model by presenting a numerically exact solution of the Coulomb-coupled QDO model by means of quantum Monte Carlo methods. We calculate the potential-energy surfaces of homogeneous QDO dimers, analyzing their properties as a function of the three tunable parameters: frequency, reduced mass, and charge. We study the coupled-QDO model behavior at short distances and show how to parameterize this model to enable an effective description of chemical bonds, such as the covalent bond in the H2 molecule.

Lunar mantle structure and composition inferred from Apollo 12 – Explorer 35 electromagnetic sounding

Constraints on the interior structure of the Moon have been derived from its inductive response, principally as measured by the magnetic transfer function (TF) between the distantly orbiting Explorer 35 satellite and the Apollo 12 surface station. The most successful prior studies used a dataset spanning 0.01–1 mHz, so the lunar response could be modeled as a simple dipole. However, earlier efforts also produced transfer functions up to 40 mHz. The smaller electromagnetic skin depth at higher frequency would better resolve the uppermost mantle—where key information about primitive lunar evolution may still be preserved—but requires a multipole treatment.I compute new profiles of electrical conductivity vs depth using both low- and high-frequency ranges of published Apollo-Explorer TFs. Using the low-frequency data, I derive temperature profiles at depths >400 km (<1 mHz) consistent with conductive heat loss and expectations of the iron (and possibly water) content of the mantle. The near-constant iron fraction (Mg# 81 ± 10) could imply efficient mixing due to now-defunct convection. Alternatively, incomplete overturn of gravitationally unstable magma-ocean cumulates could have left a heterogeneous distribution of minerals at hundred-km scales that are not resolved by electromagnetic sounding. A third explanation is that the electromagnetically probed region may be the initial equilibrium crystallization in a mantle that did not buoyantly overturn.In contrast, the high-frequency data produced higher conductivities than expected, requiring unrealistically low Mg# or high water content at depths 200–400 km. Either the published transfer functions > > 1 mHz are incorrect, or the TF multipole method at the Moon is unreliable. Future electromagnetic sounding using the magnetotelluric method can operate up to 100 s Hz and is largely insensitive to multipole effects, resolving structure to 100 km or less.

Multipole mixing effects on the angular distribution and polarization of dielectronic hypersatellite lines from highly charged helium-like ions

The angular distribution and the degree of linear polarization of the dielectronic hypersatellite lines of highly charged helium-like ions are studied by using the multiconfiguration Dirac-Fock method and density matrix theory with a focus on the multipole mixing effects. Detailed calculations have been carried out for the emission of characteristic X-rays from the (2s2p)P1,23 and P11 resonant states decay to the (1s2s)S13 state following the KLL dielectronic recombination of initial hydrogen-like ions with atomic nuclear charge from Z=22 to Z=100. It is shown that the mixing of electric dipole (E1) and magnetic quadrupole (M2) radiations significantly alters the angular distribution and the degree of linear polarization, in which the shifts are dependent on the resonant capture states and the atomic nuclear charges. The E1+M2 mixing has opposite effects for the (2s2p)P23 and (2s2p)P11 resonant states, except for the (2s2p)P11 resonance of the heavy ions with Z≳90, where the profile of angular distribution is reversed by strong mixing effects due to the contribution of the M2 term and its interference with the E1 radiative channel. The results should be of particular interest to the diagnosis of anisotropic plasmas and the test of fundamental physics in few-electron heavy ions.

In-beam gamma -ray spectroscopy of ^{94}Ag

A recoil-beta-tagging experiment has been performed to study the excited T=0 and T=1 states in the odd–odd N=Z nucleus ^{94}Ag, populated via the ^{40}Ca(^{58}Ni,1p3n)^{94}Ag reaction. The experiment was conducted using the MARA recoil separator and JUROGAM3 array at the Accelerator Laboratory of the University of Jyväskylä. Through correlating fast, high-energy beta decays at the MARA focal plane with prompt gamma rays emitted at the reaction target, a number of transitions between excited states in ^{94}Ag have been identified. The timing characteristics of these transitions confirm that they fall within decay sequences that feed the short-lived T=1 ground state of ^{94}Ag. The transitions are proposed to proceed within and between the sets of states with T=0 and T=1. Possible correspondence between some of these transitions from analog states in ^{94}Pd has been discussed, and shell-model calculations including multipole and monopole electromagnetic effects have been presented, in order to enable predictions of the decay patterns between the T=0 and T=1 states and to allow a theoretical set of Coulomb energy differences to be calculated for the A = 94T=1 analog states.

Experimental investigation of the catalyst-free reaction characteristics of micron aluminum powder with water at low and medium temperatures

Aluminum metal has a high energy density and can react with water to produce hydrogen instantly, which is environmental-friendly and safe. Aluminum has great potential to provide a good carrier for energy and hydrogen storage. The utilization of aluminum is constrained by the oxide layer on its surface. In order to promote the aluminum-water reaction to continue efficiently, the reaction needs to be activated. The modification of aluminum is often complicated and dangerous, and it is difficult to apply the hydrogen produced by the reaction and the heat released. The increase of temperature and pressure of the reaction has also been proved as a useful activation method. Continuous reactions are difficult to achieve at high temperature and pressure, and it becomes difficult to obtain reaction initiation and development processes. However, the reaction process has an essential impact on the utilization of the aluminum-water reaction. In this paper, the aluminum-water reaction process at medium temperature was investigated using micron aluminum powder. The effects of initial temperature, particle size of aluminum powder and water type on the reaction were further analyzed. In addition, the kinetic analysis of the aluminum-water reaction was carried out to obtain kinetic models. Experimental results indicate that the product of the aluminum-water reaction is Al(OH)3 at 90–150 °C. The reaction initial temperature shows a multipolar effect on the reaction between aluminum and water. The hydrogen yield from the reaction between ∼25 μm aluminum powder and tap water at 150 °C is 31.9 %. The pre-exponential factor and apparent activation energy increase with the reaction proceeding. The present research is conducive to further safe and efficient utilization of micron aluminum powder for energy conversion, and benefits the achievement of carbon peaking and carbon neutrality.

Coomassie brilliant blue G-250 acts as a potential chemical chaperone to stabilize therapeutic insulin.

Our studies show Coomassie Brilliant Blue G-250 as a promising chemical chaperone that stabilises the α-helical native human insulin conformers, disrupting their aggregation. Furthermore, it also increases the insulin secretion. This multipolar effect coupled with its non-toxic nature could be useful for developing highly bioactive, targeted and biostable therapeutic insulin.

Non-Fermi liquid behavior and quantum criticality in cubic heavy fermion systems with non-Kramers multipolar local moments

Notable non-Fermi liquid and quantum critical behaviors are observed in rare-earth metallic systems with non-Kramers local moments supporting a number of different multipolar moments. A prominent example is $\text{Pr(Ti,V)}_{2}\text{Al}_{20}$, where the non-Kramers doublet of the $\text{Pr}^{3+}$ ion allows quadrupolar and octupolar moments, but lacks a dipolar moment. Previous theoretical studies show that a single impurity Kondo problem with such an unusual local moment leads to novel non-Fermi liquid states. In this work, we investigate possible quantum critical behaviors arising from the competition between non-Fermi liquid states and multipolar-ordered phases induced by the RKKY interaction. We consider a local version of the corresponding Kondo lattice model, namely the Bose-Fermi Kondo model. Here, the multipolar local moments are coupled to fermionic and bosonic bath degrees of freedom representing the multipolar Kondo effect and RKKY interactions. Using a perturbative renormalization group (RG) study up to two loop order, we find critical points between non-Fermi liquid Kondo fixed points and a quadrupolar ordered fixed point. The critical points describe quantum critical behaviors at the corresponding phase transitions and can be distinguished by higher order corrections in the octupolar susceptibility that can be measured by ultrasound experiments. Our results imply the existence of a rich expansion of the phases and quantum critical behaviors in multipolar heavy fermion systems.

Energy absorption of an exciton-biexciton system in a quantum dot – Metal nanoparticle hybrid

We study theoretically the energy absorption rate spectrum of a coupled nanostructure composed of a semiconductor quantum dot (SQD) and a spherical metal nanoparticle (MNP) interacting with a linearly polarized electromagnetic field. A three-level ladder-type energy level scheme is used for the description of the SQD, where exciton and biexciton transitions are accounted for. We investigate the impact due to the modification of the values of a series of physical parameters on the energy absorption rate spectrum, including the intensity and the polarization direction of the applied field, the biexciton energy shift, the interparticle distance and multipole effects. We find three regular, almost Lorentzian-shaped, peaks on the SQD spectrum and three Fano-type resonance line shapes on the MNP spectrum and show that the distance between them increases with the increase of the absolute value of the biexciton energy shift. The results have potential applications in nanotechnology.

Bremsstrahlung from fully stripped tungsten (W74+) in a Debye-Hückel potential

Based on the exact relativistic multipole calculations using pure Coulomb and Debye-H\"uckel potentials, discussions of bremsstrahlung cross sections and corresponding emitted photon angular distributions from fully stripped tungsten (${\mathrm{W}}^{74+}$) are given for electron scattering at energies of 10--150 keV. Nonrelativistic dipole calculations are also presented, showing that for the above energy region, the nonrelativistic results are completely invalid and the relativistic and multipole effects must be taken into account. The reduction of bremsstrahlung cross sections due to screening of the nuclear charge is studied using the relativistic multipole method at different values of the screening length and photon energy. With an increase of electron scattering energy, the effect of the screening potential on both the dynamics of fast free electrons and the cross sections is reduced. The peak of the angular distribution of bremsstrahlung would shift towards smaller emission angles when the screening strength is reduced.

Rise and fall of non-Fermi liquid fixed points in multipolar Kondo problems

The authors study non-Fermi liquid states due to the multipolar Kondo effect by using perturbative renormalization group analysis, and differences in the type of ground state depending on whether they are considered separately or together.

Multipole lattice effects in high refractive index metasurfaces

In this Perspective, we outline the recent progress, primary achievements, and further directions in the development of high refractive index nanostructures and metasurfaces. In particular, we review the role of multipole lattice effects in resonant properties of underlying nanostructures and nanophotonic elements in detail. Planar optical designs with efficient light control at the nanoscale can be engineered based on photonic lattices that operate in the translational regime between two and three dimensions. Such transdimensional lattices include 3D-engineered nanoantennas supporting multipole Mie resonances and arranged in the 2D arrays to harness collective effects in the nanostructure. Lattice effects in the periodic nanoparticle arrays have recently attracted a lot of attention as they enable not only spectrally narrow resonant features but also resonance position tuning over a broad range. The recent results indicate that different nanoparticle multipoles not only produce resonant spectral features but are also involved in the cross-multipole coupling, and these effects need to be accounted for in photonic designs. Multipole lattice phenomena provide an effective way to control nanoparticle resonances, facilitate excitation of additional multipoles through a cross-multipole coupling, and enable light localization in planar photonic elements. We review different effects related to the same- and cross-multipole interactions in the arrays. Both infinite and finite arrays, as well as lattices of complex-shape nanoparticles, which allow out-of-plane multipole excitations, are considered.

Stimuli-responsive granular crystals assembled by dipolar and multipolar interactions.

This work describes granular crystals held together by unusual, multipolar interactions and, under the application of an external bias, undergoing reversible structural transitions between closed and open forms. The system comprises two types of polymeric beads agitated on one or between two conductive plates and gradually acquiring charges by contact electrification. The charges thus developed induce a series of electrostatic images in the conductive supports and, in effect, the beads interact via dipolar or multipolar interactions, enabling the stabilization of non-electroneutral crystals. Furthermore, under an applied bias, the beads become polarized and their complex interactions (due to the series of image charges as well as series of image dipoles) result in open-pore crystals which return to compact forms upon bias removal. These effects are rationalized by analytical calculations, and the crystal structures observed in the experiments are reproduced by molecular dynamics simulations.

Multipolar effects in the hysteresis behavior of 2D arrays of compass needles: Experiments and simulations

Despite its easy experimental implementation, macroscopic systems composed of compass needles array show a rich and complex variety of physical phenomena that are not yet fully understood. In this work we consider the experimental realization of a square lattice of equally spaced millimeter sized compass needles, as well as its theoretical approach taking into account a proper higher order moments expansion of the magnetic potential, considering the actual shape of a compass needle. A Monte Carlo simulation, done using interaction energy value given by the previous expansion, showed excelent agreement with experimental results for the squared array magnetization process. Rather than the unique commonly considered dipolar contribution, the results evidence the importance of multipole expansion in considering interactions among magnetic elements with finite size, attributing to the magnetic particle shape a critical importance that could raise higher order contributions. In addition to the clear pedagogical relevance, the conclusions deserve attention, and reopen the discussion of whether dipolar interaction is the only relevant contribution to be considered in theoretical models in which magnetostatic interactions are important, e.g. superparamagnetic nanoparticles models.

Tuning the ultralow β* optics at the KEK Accelerator Test Facility 2

For future linear colliders, a nanometer-scale beam size at the interaction point (IP) is one of the most challenging technical aspects. To explore the feasibility of a final focus system with a high chromaticity level, comparable to that of the Compact Linear Collider, the ultralow ${\ensuremath{\beta}}^{*}$ optics has been proposed and tuned at the KEK Accelerator Test Facility 2. In this paper, the recent experimental results are presented, which demonstrate the capability of achieving and stabilizing a vertical average beam size of 60 nm and below at the virtual IP. The observed vertical beam size is about 20 nm above the numerical predictions in the presence of static and dynamic imperfections. We interpret this discrepancy as beam size growth due to multipole fields, beam jitters and wakefield effects, and diagnostic errors.