Intrinsic Electric Dipole Moment Research Articles

Construction of spontaneously polarized ceramic via synergistic mechanical activation‒Biomimetic mineralization for activating air and water

Spontaneously polarized crystals with intrinsic electric dipole moment have attracted immense interest as excellent functional materials for extensive applications. It is of great significance to engineer sustainable spontaneously polarized materials with fascinating characteristics and performance for activating air and water. Herein, a novel strategy based on the synergy of mechanical activation (MA) and biomimetic mineralization (BM) was created to construct spontaneously polarized ceramic. MA induced the structural damage of clay and promoted the dissolution of ions and the release of free proteins, contributing to the formation of silicate precursor in BM process. After high temperature firing, the silicate precursor in clay was converted to form KCa3AlCa3Si4O16 (hexagonal crystal system, L6 symmetry type, and P63 space group) in the resulting spontaneously polarized ceramic. The non-centrosymmetric structure of KCa3AlCa3Si4O16 and the high intrinsic electric dipole moments contributed by K(1) polyhedrons resulted in high spontaneous polarization (0.2322 μC/cm2) and far-infrared emissivity (0.951) of spontaneously polarized ceramic. In air, spontaneously polarized ceramic can activate H2O and O2 molecules to form negative air ions owing to surface electric field. In water, spontaneously polarized ceramic can disaggregate large water clusters to form small water clusters ascribed to surface electric field and far-infrared emission; water pH can be regulated from weak acidity to approximate neutrality via the capture of electrons by H+ ions to produce releasable hydrogen gas. This work provides great promise for rational design and synthesis of spontaneously polarized materials for functional applications.

The mechanism of pyroelectricity in polar material hemimorphite

It is known that a crystal structure and symmetry determine the physical properties of materials. Lattice distortion can strongly affect the symmetry of the crystal structure. Polar materials show changes in polarization with temporal fluctuations of temperature due to the asymmetry. As a polar crystal, hemimorphite shows excellent pyroelectric properties. However, to date, there are a few studies on its intrinsic physical properties, and the mechanism of its pyroelectricity remains unclear. In this paper, single-crystal x-ray diffraction measurement was carried out to obtain the atomic positions at 100–400 K. Furthermore, the electric dipole moments of [ZnO4] and [SiO4] polyhedrons along a, b, and c axes have been calculated. The calculated pyroelectric coefficient derived from the intrinsic electric dipole moment was compared with the experimental measurement. The results indicate that the pyroelectric coefficients of hemimorphite at different temperatures mainly come from the variation of the electric dipole moment of [ZnO4] and [SiO4] polyhedrons along the c axis. The electric dipole moment changes as a function of temperature from 100 to 400 K, which is induced by the random lattice distortion. It is found that pyroelectricity is strongly correlated with the random lattice distortion. The establishment of the relationship between lattice distortion and pyroelectricity helps us to regulate the specific electrical parameters of the material, which may lead to future work in energy harvesting and further properties.

Experimental review of octupole correlations in the A≈80 mass region

This review presents the nuclei with octupole correlations in the [Formula: see text] mass region. The status of experimental data on the behavior of the energy displacement, the [Formula: see text] transition probability and intrinsic electric dipole moment have been reviewed. The evolutions of the octupole strength with the numbers of protons and neutrons are discussed.

Topological Interface between Pfaffian and Anti-Pfaffian Order in ν=5/2 Quantum Hall Effect.

A recent thermal Hall experiment triggered renewed interest in the problem of ν=5/2 quantum Hall effect, which motivated novel interpretations based on the formation of mesoscopic puddles made of Pfaffian and anti-Pfaffian topological orders. Here, we study an interface between the Pfaffian and anti-Pfaffian states, which may play crucial roles in thermal transport, by means of state-of-the-art, density-matrix renormalization group simulations. We demonstrate that an intrinsic electric dipole moment emerges at the interface, similar to the "p-n" junction sandwiched between N-type and P-type semiconductor. Importantly, we elucidate the topological origin of this dipole moment, whose formation is to counterbalance the mismatch of guiding-center Hall viscosity of bulk Pfaffian and anti-Pfaffian states. In addition, these results imply that the formation of a dipole moment could be helpful to stabilize the puddles made of Pfaffian and anti-Pfaffian states in experimental conditions.

Enhanced Light Emission by Magnetic and Electric Resonances in Dielectric Metasurfaces

AbstractAn enhanced emission of high quantum yield molecules coupled to dielectric metasurfaces formed by periodic arrays of polycrystalline silicon nanoparticles is demonstrated. Radiative coupling of the nanoparticles, mediated by in‐plane diffraction, leads to the formation of collective Mie scattering resonances or Mie surface lattice resonances (M‐SLRs), with remarkable narrow line widths. These narrow line widths and the intrinsic electric and magnetic dipole moments of the individual Si nanoparticles allow resolving electric and magnetic M‐SLRs. Incidence angle‐ and polarization‐dependent extinction measurements and high‐accuracy surface integral simulations show unambiguously that magnetic M‐SLRs arise from in‐ and out‐of‐plane magnetic dipoles, while electric M‐SLRs are due to in‐plane electric dipoles. Pronounced changes in the emission spectrum of the molecules are observed, with almost a 20‐fold enhancement of the emission in defined directions of molecules coupled to electric M‐SLRs, and a fivefold enhancement of the emission of molecules coupled to magnetic M‐SLRs. These measurements demonstrate the potential of dielectric metasurfaces for emission control and enhancement, and open new opportunities to induce asymmetric scattering and emission using collective electric and magnetic resonances.

Direct measurement of the intrinsic electric dipole moment in pear-shaped thorium-228

It is now well established that atomic nuclei composed of certain combinations of protons and neutrons can adopt reflection-asymmetric, or octupole-deformed, shapes at low excitation energy. These nuclei show promise in the search for a permanent atomic electric dipole moment, the existence of which has implications for physics beyond the Standard Model. Theoretical studies have suggested that certain isotopes of thorium may have the largest octupole deformation. However, due to experimental challenges, the extent of the octupole collectivity in the low-energy states in these thorium nuclei has not yet been demonstrated. This paper reports measurements of the lifetimes of low-energy states in 228Th (Z = 90) undertaken using the mirror symmetric centroid difference method, which is a direct electronic fast-timing technique. Lifetime measurements of the low-lying Jp = 1- and 3- states, which are the first for a thorium isotope, have allowed the B(E1) rates and the intrinsic dipole moment to be determined. The results are in agreement with those of previous theoretical calculations allowing the extent of the octupole deformation of 228Th to be estimated. This study indicates that the nuclei 229Th and 229Pa (Z = 91) may be good candidates for the search for a permanent atomic electric dipole moment.

Enhanced P,T-violating nuclear magnetic quadrupole moment effects in laser-coolable molecules.

Nuclear magnetic quadrupole moments (MQMs), such as intrinsic electric dipole moments of elementary particles, violate both parity and time-reversal symmetry and, therefore, probe physics beyond the standard model. We report on accurate relativistic coupled cluster calculations of the nuclear MQM interaction constants in BaF, YbF, BaOH, and YbOH. We elaborate on estimates of the uncertainty of our results. The implications of experiments searching for nonzero nuclear MQMs are discussed.

Dipoles in quantum field theory

In quantum field theory, a fundamental spin-12 particle can have intrinsic magnetic and electric dipole moments. Herein, we examine the way in which a charged fermion or photon is scattered by a massive neutral fermion via its dipole moment. In the low-energy limit, the field theoretic scattering amplitude can be related to a semi-classical electromagnetic interaction Hamiltonian. We find, in this limit, that the dipole field of the fundamental particle is that of a classical pure dipole, including the correct contact field. Additionally, we examine the optical properties of a medium consisting of magnetic dipoles. By computing the Compton scattering amplitude for a magnetic dipole, we find that a medium of polarized dipoles is circularly birefringent; that is, the index of refraction depends upon the polarization of the light. Our presentation is geared toward advanced undergraduate or beginning graduate students.

The origin of pyroelectricity in tourmaline at varying temperature

Although tourmaline is a common pyroelectric material, the origins of pyroelectricity in tourmaline at varying temperature are still unclear. In the present work, based on the crystallographic data obtained from X-ray diffraction refinement, we calculated the intrinsic electric dipole moments of the typical coordination polyhedra ([XO9], [YO6], [ZO6], [TO4], [BO3]) in tourmaline unit cell along c-axis at various temperature ranging from 25 °C to 300 °C. The theoretical pyroelectric coefficients obtained based on these intrinsic electric dipole moments were consistent with the experimental results, indicating that the pyroelectric coefficient of tourmaline at varying temperature is mainly originated from the intrinsic electric dipole moment changes of the [XO9], [YO6], [ZO6], [TO4], [BO3] polyhedra along c-axis. Furthermore, the deformations of the [SiO4] tetrahedra and [BO3] polyhedra along c-axis direction were dominant in the change of total intrinsic electric dipole moment in the tourmaline unit cell. These results were further supported by the analyses of the polarized Raman spectra and infrared spectra.

Phase Locking the Spin Precession in a Storage Ring.

This Letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV/c bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate (≈121 kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a 1 standard deviation range of σ=0.21 rad. The minimum possible adjustment was 3.7mHz out of a revolution frequency of 753kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles.

How to Reach a Thousand-Second in-Plane Polarization Lifetime with 0.97-GeV/c Deuterons in a Storage Ring.

We observe a deuteron beam polarization lifetime near 1000s in the horizontal plane of a magnetic storage ring (COSY). This long spin coherence time is maintained through a combination of beam bunching, electron cooling, sextupole field corrections, and the suppression of collective effects through beam current limits. This record lifetime is required for a storage ring search for an intrinsic electric dipole moment on the deuteron at a statistical sensitivity level approaching 10^{-29} e cm.

Prospects for the formation of ultracold polar ground state KCs molecules via an optical process

Heteronuclear alkali-metal dimers represent the class of molecules of choice for creating samples of ultracold molecules exhibiting an intrinsic large permanent electric dipole moment. Among them, the KCs molecule, with a permanent dipole moment of 1.92 Debye still remains to be observed in ultracold conditions. Based on spectroscopic studies available in the literature completed by accurate quantum chemistry calculations, we propose several optical coherent schemes to create ultracold bosonic and fermionic KCs molecules in their absolute rovibrational ground level, starting from a weakly bound level of their electronic ground state manifold. The processes rely on the existence of convenient electronically excited states allowing an efficient stimulated Raman adiabatic transfer of the level population.

Polarimetry for Stored Polarized Hadron Beams

Feasibility studies using 0.97-GeV/c polarized deuterons to determine the suitability of storage rings in the search for intrinsic electric dipole moments have led to new developments in storage ring polarimeters. Efficiency has increased with the use of thick carbon targets. The calibration of the effects of geometric and rate-dependent errors has made possible the subtraction of these systematic errors, resulting in sensitivities at or below 10[Formula: see text] to polarization changes during the time of the store. Tagging polarimeter events with the clock time had made available the turn number for each event, making possible longitudinal profile and horizontal polarization measurements. These have been used to explore the correction of second-order contributions to decoherence using sextupole fields, yielding horizontal polarization lifetimes as long as 20 minutes. Such studies may be extended to protons and 3He.

Screening of electron electric dipole moment through the Foldy-Wouthuysen representation

The existent of the intrinsic electric dipole moments (EDM) lead to CP violation in a physical system. In the non-relativistic and point like limits, the effects of them in atoms are canceled which is well-known as Schiff screening effects. It is why that the energy shift due to the EDM is proportional to the expectation value of which vanishes in non-relativistic limit. In this paper, using Foldy-Wouthuysen representation we remove the odd terms (those terms mix the positive and negative energy solutions) up to order and then study the Schiff screening effects.

New experimental limit on the electric dipole moment of the electron in a paramagnetic insulator

We report results of an experimental search for the intrinsic Electric Dipole Moment (EDM) of the electron using a solid-state technique. The experiment employs a paramagnetic, insulating gadolinium gallium garnet (GGG) that has a large magnetic response at low temperatures. The presence of the eEDM would lead to a small but non-zero magnetization as the GGG sample is subject to a strong electric field. We search for the resulting Stark-induced magnetization with a sensitive magnetometer. Recent progress on the suppression of several sources of background allows the experiment to run free of spurious signals at the level of the statistical uncertainties. We report our first limit on the eEDM of $(-5.57 \pm 7.98 \pm 0.12)\times$10$^{-25}$e$\cdot$cm with 5 days of data averaging.

Reexamination of the standard model nucleon electric dipole moment

The Cabibbo-Kobayashi-Maskawa matrix in the Standard Model is currently the only experimentally-confirmed source of CP-violation. The intrinsic electric dipole moment of the nucleon induced by this CP-phase via hadronic loop and pole diagrams has been studied more than two decades ago, but the existing calculation is subject to various theoretical issues such as the breakdown of chiral power counting and uncertainties in the determination of low energy constants. We carry out an up-to-date re-analysis on both one-loop and pole diagram contributions to the nucleon electric dipole moment based on Heavy Baryon Chiral Perturbation Theory in a way that preserves power counting, and redo the determination of the low energy constants following the results of more recent articles. Combined with an estimation of higher-order contributions, we expect the long-distance contribution to the Standard Model nucleon electric dipole moment to be approximately $(1\times10^{-32}-6\times10^{-32})e\,\mathrm{cm}$.

Core-polarization studies of nuclear-Schiff-moment-induced permanent electric dipole moments of atomicXe129,Yb171, andRa225

We have calculated the intrinsic electric dipole moments (EDMs) of $^{129}\mathrm{Xe}$, $^{171}\mathrm{Yb}$, $^{225}\mathrm{Ra}$ atoms induced by the nuclear Schiff moment (NSM). We use the coupled perturbed Hartree-Fock [CPHF] framework to perform this calculation. In this work, the effects of electron correlation on atomic EDMs are studied in CPHF framework by gradual inclusion of virtual orbitals of higher symmetries. Individual orbital contributions to the final magnitude of the EDM are presented. The results for the NSM-induced EDM for these atoms show a trend similar to the electron-nucleon tensor-pseudotensor (T-PT)-induced EDM, the study of which was performed elsewhere. This behavior can be attributed to the fact that the influence of virtual orbitals of higher symmetry on the magnitude of EDM is essentially the same for both T-PT and NSM-induced atomic EDMs. However, we also report in this paper, that the most dominant contribution to the atomic EDM of $^{129}\mathrm{Xe}$, $^{171}\mathrm{Yb}$, $^{225}\mathrm{Ra}$ atoms induced by the NSM arises from the ${s}_{1/2}\text{\ensuremath{-}}{p}_{3/2}$ pairings rather than the ${s}_{1/2}\text{\ensuremath{-}}{p}_{1/2}$ pairings, which were the dominantly contributing pairings for the electron-nucleon tensor-pseudotensor-induced atomic EDM.

Guiding-center Hall viscosity and intrinsic dipole moment along edges of incompressible fractional quantum Hall fluids

The discontinuity of guiding-center Hall viscosity (a bulk property) at the edges of incompressible quantum Hall fluids is associated with the presence of an intrinsic electric dipole moment on the edge. If there is a gradient of drift velocity due to a nonuniform electric field, the discontinuity in the induced stress is exactly balanced by the electric force on the dipole. The total Hall viscosity has two distinct contributions: a ``trivial'' contribution associated with the geometry of the Landau orbits and a nontrivial contribution associated with guiding-center correlations. We describe a relation between the guiding-center edge-dipole moment and ``momentum polarization,'' which relates the guiding-center part of the bulk Hall viscosity to the ``orbital entanglement spectrum (OES).'' We observe that using the computationally more-onerous ``real-space entanglement spectrum'' just adds the trivial Landau-orbit contribution to the guiding-center part. This shows that all the nontrivial information is completely contained in the OES, which also exposes a fundamental topological quantity, $\ensuremath{\gamma}$ = $\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{c}\ensuremath{-}\ensuremath{\nu}$, the difference between the ``chiral stress-energy anomaly'' (or signed conformal anomaly) and the chiral charge anomaly. This quantity characterizes correlated fractional quantum Hall fluids and vanishes in uncorrelated integer quantum Hall fluids.

Measuring the polarization of a rapidly precessing deuteron beam

This paper describes a time-marking system that enables a measurement of the in-plane (horizontal) polarization of a 0.97-GeV/c deuteron beam circulating in the Cooler Synchrotron (COSY) at the Forschungszentrum J\"ulich. The clock time of each polarimeter event is used to unfold the 120-kHz spin precession and assign events to bins according to the direction of the horizontal polarization. After accumulation for one or more seconds, the down-up scattering asymmetry can be calculated for each direction and matched to a sinusoidal function whose magnitude is proportional to the horizontal polarization. This requires prior knowledge of the spin tune or polarization precession rate. An initial estimate is refined by re-sorting the events as the spin tune is adjusted across a narrow range and searching for the maximum polarization magnitude. The result is biased toward polarization values that are too large, in part because of statistical fluctuations but also because sinusoidal fits to even random data will produce sizeable magnitudes when the phase is left free to vary. An analysis procedure is described that matches the time dependence of the horizontal polarization to templates based on emittance-driven polarization loss while correcting for the positive bias. This information will be used to study ways to extend the horizontal polarization lifetime by correcting spin tune spread using ring sextupole fields and thereby to support the feasibility of searching for an intrinsic electric dipole moment using polarized beams in a storage ring. This paper is a combined effort of the Storage Ring EDM Collaboration and the JEDI Collaboration.

Nuclear electric dipole moments for the lowest1/2+states in Xe and Ba isotopes

The electric dipole moments for the lowest $1/{2}^{+}$ states of Xe and Ba isotopes are calculated in terms of the nuclear shell model, which includes two-body nucleon interactions violating parity and time-reversal invariance. Using the wave functions thus obtained, the nuclear electric dipole moments arising from the intrinsic nucleon electric dipole moments and also from asymmetric charge distribution are calculated. The upper limits for the nuclear electric dipole moments of Xe and Ba isotopes are estimated.