Magnetic Dipole Research Articles

Tunable bistability, optomechanical and magnomechanically induced transparency in opto-magnomechanical system

We investigate theoretically the optical properties of a hybrid optomechanical system embedded with a yttrium iron garnet (YIG) sphere. It is considered that YIG interacts with a single mode of the microcavity through magnetic dipole coupling. To enhance the magnomechanical coupling, the magnon mode is directly driven by a microwave field. The microcavity is driven by the control and probe field. The study of steady-state dynamics of the system shows bistable behavior. Furthermore, optomechanically induced transparency under the influence of a strong control field in the system is explored. In addition, magnomechanically induced transparency (MMIT) due to the presence of nonlinear magnon–phonon interaction is studied. Fano like shape is observed in MMIT. The impact of different system parameters is studied. Our results will provide a theoretical approach to understand opto-magnomechanical systems. These results may be useful in all optical switching devices and optical transistors.

Time-dependent quantum/continuum modeling of plasmon-enhanced electronic circular dichroism.

In this work, we present a multiscale real-time approach to study the plasmonic effects of a metal nanoparticle (NP) on the electronic circular-dichroism (ECD) spectrum of a chiral molecule interacting with it. The method is based on the time-evolution of the molecule's time-dependent wavefunction, expanded in the eigenstates of a perturbed Hamiltonian. A quantum description of the molecular system is coupled to a classical representation of the NP via a continuum model. The method is applied to methyloxirane and peridinin at various distances (1, 3, and 5nm) with respect to a gold NP surface. While no remarkable effect is observed for methyloxirane at any studied distance, an enhancement appears when the peridinin lies at 1nm and the pulse is linearly polarized perpendicularly to the molecular axis, with the ECD signal centered at 4.1eV increased by a factor of around 20. These results are rationalized looking at the gap between the plasmonic peak of the NP at around 2.5eV and the molecular excitations: the smaller the gap between molecular and plasmonic excitations, the larger the plasmonic enhancement of the ECD signal. Moreover, ECD peaks are selectively enhanced due to the favorable coupling between the pulse polarization and the combined effect of electric and magnetic dipole moments. This approach allows one to go through the electronic structure and dynamics of chiral molecules for obtaining a realistic description of plasmon-mediated ECD spectra, e.g., paving the way to applications to molecules of biological relevance interacting with nanostructures of experimental interest.

A novel Dy[formula omitted] doped Zn2V2O7 nanoparticles: Photoluminescence and electrochemical studies for display and supercapacitor applications

A novel series of Dy3+-doped Zn2V2O7 (ZV) nanoparticles (NPs) spanning concentrations from 1 to 9 mol% was synthesized via Menthaspicata leaves extract-mediated solution combustion method. Upon Dy3+ doping, the diffraction pattern matches well with the monoclinic crystal structure with the C2/c(2/m) space group of ZV host matrix. Morphological analysis revealed a transition from irregularly shaped NPs to hexagonal shaped NPs with varying dopant concentration. The crystallite size estimated via Scherrer’s method correlated closely with transmission electron microscopy analysis. Determination of the optical band gap from Tauc’s plot using UV–Visible absorption indicated a tuning from 3.045 to 2.986 eV with increasing dopant concentration. Under 266 nm excitation, the peak at 489 and 586 nm corresponds to 4F9/2→6H15/2 (Magnetic dipole) and 4F9/2→6H13/2 (electric dipole) transition of Dy3+ ion. The dominance of the blue emission (MD) over the yellow emission (ED) of Dy3+ indicates the symmetric nature of the host. The sample exhibits 7 mol % as the optimal doping content. CIE coordinates distinctly falls within the blue region with increasing dopant concentration, with an average color-coordinated temperature of 19902 K, indicative of a cooler appearance. Moreover, cyclic voltammetry analysis provided valuable insights into redox reactions, electrode kinetics, and overall electrochemical behavior, while Electrochemical Impedance Spectroscopy (EIS) offered information on ion transport kinetics. Galvanostatic Charge–Discharge (GCD) analysis revealed super capacitance values ranging from 85.79 F/g to 143.92 F/g at 10 mV/s scan rate, with increasing dopant concentration, highlighting the material’s potential for applications in energy storage and display technology.

Electroless Synthesis of Cobalt Nanowires in Magnetic Field and their Characterization by Resonant Magnetometry Methods

In this paper, a simple and effective low-temperature electroless chemical method that provides the synthesis of cobalt micro- and nanowires due to the processes of self-organization of magnetic cobalt nanoparticles under the influence of a magnetic field, using the technology of chemical synthesis of magnetic nanoparticles and nanowires is proposed. Cobalt nanoparticles have magnetic dipole moments. An external magnetic field forces them to be oriented parallel to it. Dipole-dipole interactions between magnetic nanoparticles lead to attraction between cobalt nanoparticles leading to their self-organization into nanowires, reducing their total energy. The resulting smaller nanoparticles fill the gaps between the ordered nanoparticles, leading to the formation of smooth cobalt nanowires. The magnetic and structural properties of the synthesized and commercial nanowires polarized by a magnetic field in the epoxy matrix were studied using the resonant radio-frequency magnetometry and electron microscopy methods. These methods are of interest for optimizing the coercive force of cobalt nanowires with a view to their possible use in creating permanent magnets that do not use rare earth elements, as well as in information processing devices and sensors.

Performance of an LAPPD in magnetic fields

Magnetic fields affect the response of Micro-Channel Plate (MCP)-based detectors, although the effect is smaller than that for conventional photo-multiplier tubes. The main effect of the field is a reduction in gain and efficiency.In this article, we report our studies of the effects of the magnetic field on the Large Area Picosecond PhotoDetectors (LAPPDs), photosensors of large sensitive area based on MCP technology. The LAPPD under study was the most recent, short stack, 10μm pore model, expected to have the best capabilities to withstand magnetic field distortions. The measurements were performed at CERN on the MNP-17 and M113 vertical dipole magnets in magnetic fields up to ∼ 1.5 T. The results show the exponential drop of the LAPPD gain as a function of the magnetic field strength, with a rather mild dependence on the angular distribution. The relative photon detection efficiency in magnetic field is also affected. However, both the gain and the efficiency can be partially recovered by increasing the LAPPD bias voltages. Geometrical effects on the anode charge spot and time resolution were also studied.

Layered Babinet complementary patterns acting as asymmetric negative index metamaterial

Azimuthal orientation and handedness dependence of the optical responses, accompanied by asymmetric transmission and asymmetric dichroism, were demonstrated on multilayers constructed with subwavelength periodic arrays of Babinet complementary miniarrays, illuminated by linearly and circularly polarized light. In case of single-sided illumination asymmetric optical responses were observed at the spectral location of maximal cross-polarization that is accompanied by radiative electric dipoles and weak, slowly-rotating in-plane magnetic dipoles on the nano-objects; where the outgoing waves are elliptically (almost circularly) polarized. The negative index material phenomenon was demonstrated, where the electric and magnetic dipoles overlap both spatially and spectrally. The negative index material (NIM) phenomenon is accompanied by electric multipoles that add up non-radiatively and correlates with the strong, pronouncedly-tilted, rotating magnetic dipoles characteristic on the nano-entities, where the outgoing waves are linearly (slightly elliptically) polarized. By illuminating the multilayer with two counter-propagating circularly polarized beams it was proven that asymmetrical normal component displacement currents at the bounding interfaces, arising along flat and tilted bands, accompany the asymmetric copolarized and cross-polarized transmission. The latter correlates with the asymmetric dichroism in the cross-polarized signal observed in case of single-sided circularly polarized light illumination. The dispersion maps in the single-sided asymmetrical co-polarized reflectance and absorptance indicate flat bands of analogous and complementary extrema, proving the partially dichroic nature of the observed asymmetric phenomena. The Tellegen (chirality) coefficients exhibit a maximum in a spectral region coincident with the asymmetric transmission (maximal polarization rotation in the 90° azimuthal orientation). The multilayer is proposed as an ultrathin NIM and nonreciprocal nanophotonic element.

Interferometric Near-field Fano Spectroscopy of Single Halide Perovskite Nanoparticles.

Semiconducting halide perovskite nanoparticles support Mie-type resonances that confine light on the nanoscale in localized modes with well-defined spatial field profiles yet unknown near-field dynamics. We introduce an interferometric scattering-type near-field microscopy technique to probe the local electric field dynamics at the surface of a single MAPbI3 nanoparticle. The amplitude and phase of the coherent light scattering from such modes are probed in a broad spectral range and with high spatial resolution. In the spectral domain, we uncover a Fano resonance with a 2π phase jump. In the near-field dynamics, this Fano resonance gives rise to a destructive interference dip after a few femtoseconds. Mie theory suggests that the interference between electric quadrupole and magnetic dipole modes of the particle, with spectra affected by resonant interband absorption of MAPbI3, lies at the origin of this effect. Our results open up a new approach for probing local near-field dynamics of single nanoparticles.

Reply to “Comment on ‘What is the force on a magnetic dipole?’ ”

Abstract I try to respond to the Comment by Kholmetskii, Missevitch, and Yarman on my paper, “What is the force on a magnetic dipole?”, but NOTHING in their Comment is about my paper.

Constraints on Covariant Dark-Matter–Nucleon Effective Field Theory Interactions from the First Science Run of the LUX-ZEPLIN Experiment

The LUX-ZEPLIN (LZ) experiment is a dual-phase xenon time project chamber operating in the Sanford Underground Research Facility in South Dakota, USA. We report on the results of a relativistic extension to the nonrelativistic effective field theory (NREFT) from a 5.5 t fiducial mass and 60 live days of exposure. We present constraints on couplings from covariant interactions arising from the coupling of vector, axial currents, and electric dipole moments of the nucleon to the magnetic and electric dipole moments of the weakly interacting massive particle which cannot be described by recasting previous results described by an NREFT. Using a profile-likelihood ratio analysis, in an energy region between 0 keVnr to 270 keVnr, we report 90% confidence level exclusion limits on the coupling strength of five interactions in both the isoscalar and isovector bases. Published by the American Physical Society 2024

Radiative decay rates for magnetic dipole (M1) and electric quadrupole (E2) transitions between low-lying levels within the 4f3 ground configuration of Pr III

Abstract A new set of theoretical radiative decay rates characterizing forbidden transitions in doubly charged praseodymium (Pr III) is reported in the present paper. More precisely, transition probabilities were computed for all magnetic dipole (M1) and electric quadrupole (E2) lines involving the lowest energy levels of the 4f$^3$ ground configuration located below 20000 cm$^{-1}$ since the levels above this limit are preferentially depopulated by allowed electric dipole (E1) transitions. The calculations were carried out using different computational strategies based firstly on the pseudo-relativistic Hartree-Fock (HFR) method and secondly on the fully relativistic Multiconfiguration Dirac-Hartree-Fock (MCDHF) method. The comparison between the results obtained by these independent approaches makes it possible to estimate their reliability. Comparisons with the few previously published data were also made. In addition, some astrophysical implications were deduced from the new atomic parameters computed in the present work, such as the possible presence of [Pr III] lines in the infrared spectra recorded by the {\it James Webb Space Telescope} ($JWST$) in the context of the investigation of kilonovae in their nebular phase, i.e. several days after neutron star mergers.

Enhancing Antireflection Based on a Symmetry-Dependent Kerker Effect.

The significance of antireflection has persisted over time due to its numerous optical applications. To achieve broadband antireflection, multiple element-based designs using graded-index films or multiresonant nanostructures have been conventionally employed. In this work, we propose an additional degree of freedom in developing antireflection by manipulating the orientation angles of nanostructures to achieve the symmetry-dependent Kerker condition. Under the excitation of multipoles in higher-order resonances, which typically complicates the interference condition, the perfect Kerker condition is demonstrated without backward leakage of power at a wavelength significantly shorter than the excitation bandwidth of electric and magnetic dipoles. Such a condition can be directly linked to the symmetry of resonators and maximized by suppressing the near-field coupling and optimizing polarization-related spatial parities. We experimentally demonstrate the symmetry-dependent Kerker condition and polarization-independent antireflection at the midwave infrared range, which has attracted increasing attention in emerging imaging and sensing fields.

Repercussions of thermally stratified magnetic dipole for mixed convectively heated Darcy-Forchheimer Carreau-Yasuda nanofluid flow via viscous dissipation analysis

Nowadays nanotechnology is progressing speedily with the passage of time, consequently the research on innovative fluid termed as nanofluid is at its peak. Invention of nanofluid has made a revolution in engineering and chemical processes due to its enhanced heat transmission characteristics along with environmental friendliness as well as financially affordability of nanofluid are causes of its attraction among the research community. In current study the basic aim is to scrutinize a rheological ferrofluid model with magnetic effects. The procedure for conversion of coupled P.D. Es into coupled set of O.D.Es which is performed by use of similarity variables. The numerical scheme used here is bvp4c scheme for obtaining the required numerical outcomes. A comprehensive review of graphical illustration for fluid's temperature, velocity as well as concentration is delivered here. We inspected that with upsurge of parameter for Brownian motion resultantly concentration of fluid declines while increase in thermal profile is noted.

Magnetic manipulation of unknown and complex conductive nonmagnetic objects with application in the remediation of space debris

This article extends recent work in magnetic manipulation of conductive, nonmagnetic objects using rotating magnetic dipole fields. Eddy-current-based manipulation provides a contact-free way to manipulate metallic objects. We are particularly motivated by the large amount of aluminum in space debris. We previously demonstrated dexterous manipulation of solid spheres with all object parameters known a priori. This work expands the previous model, which contained three discrete modes, to a continuous model that covers all possible relative positions of the manipulated spherical object with respect to the magnetic field source. We further leverage this new model to examine manipulation of spherical objects with unknown physical parameters by applying techniques from the online-optimization and adaptive-control literature. Our experimental results validate our new dynamics model, showing that we get improved performance compared to the previously proposed model, while also solving a simpler optimization problem for control. We further demonstrate the first physical magnetic manipulation of aluminum spheres, as previous controllers were only physically validated on copper spheres. We show that our adaptive control framework can quickly acquire useful object parameters when weakly initialized. Finally, we demonstrate that the spherical-object model can be used as an approximate model for adaptive control of nonspherical objects by performing magnetic manipulation of a variety of objects for which a spherical model is not an obvious approximation.

CPT-Odd effects on the electromagnetic properties of charged leptons in the Standard Model Extension

Abstract The impact of the CPT-Odd electroweak gauge sector of the Standard Model Extension on the magnetic dipole moment of charged leptons is studied. This gauge sector is characterized by the (k1)µ and (k2)µ Lorentz coefficients, which have positive mass dimension because they are associated with a UY (1)-invariant and with an SUL(2)-invariant dimension-three operators, respectively. They belong to the category of relevant interactions, which have strong effects on low-energy observables. We present a comprehensive study on the impact of this sector on the magnetic dipole moment of charged leptons, up to second order in these Lorentz coefficients, both at the tree and one-loop levels. We find that the first-order contributions in the Lorentz coefficients at the tree and one-loop levels depend on energy, while second-order ones at the tree-level do not. As for second-order one-loop effects, there are both energy-dependent and energy-independent contributions, but we have focused only on those of the latter type. We find that the tree-level contributions are suppressed with respect to the one-loop ones by at least a factor of (m2l /m2Z). We find that the contribution to the dipole associated with the electron is by far the dominant one, as it can be up to fourteen orders of magnitude greater than that of the muon and up to sixteen orders greater than that of the tau. The Lorentz coefficient (kAF )µ of the Carroll-Field-Jackiw’s QED is given by a linear combination of the (k1)µ and (k2)µ vectors. Assuming thatcollinear, we obtain an upper bound of|k12|,|k22| ≫ |k2AF| and taking (kAF)µ = 0, which implies that (|||−(3.49 × 10-4)(k2)0me + k2 | k1)µ and (k2)µ are.

Inversion of circularly polarized luminescence by electric current flow during transition.

The development of chiral compounds exhibiting circularly polarized luminescence (CPL) has advanced remarkably in recent years. Designing CPL-active compounds requires an understanding of the electric transition dipole moment (μ) and the magnetic transition dipole moment (m) in the excited state. However, while the direction and magnitude of μ can, to some extent, be visually inferred from chemical structures, m remains elusive, posing challenges for direct predictions based on structural information. This study utilized binaphthol, a prominent chiral scaffold, and achieved CPL-sign inversion by strategically varying the substitution positions of phenylethynyl (PE) groups on the binaphthyl backbone, while maintaining consistent axial chirality. Theoretical investigation revealed that the substitution position of PE groups significantly affects the orientation of m in the excited state, leading to CPL-sign inversion. Furthermore, we propose that this CPL-sign inversion results from a reversal in the rotation of instantaneous current flow during the S1 → S0 transition, which in turn alters the orientation of m. The current flow can be predicted from the chemical structure, allowing anticipation of the properties of m and, consequently, the characteristics of CPL. This insight provides a new perspective in designing CPL-active compounds, particularly for C2-symmetric molecules where the S1 → S0 transition predominantly involves LUMO → HOMO transitions. If μ represents the directionality of electron movement during transitions, i.e., the "difference" in electron locations before and after transitions, then m could be represented as the "path" of electron movement based on the current flow during the transition.

Closed-form expressions for magnetic polarizabilities of circular apertures excited by nonuniform magnetic fields

Abstract The problem of electromagnetic penetration through an aperture in a perfectly electrically conducting plane is a classical problem in electromagnetic theory and applications. This work aims to investigate the behavior of an electrically small aperture when excited by nonuniform magnetic fields. Based on the Taylor expansion of the exact solution in integral form of the corresponding mixed boundary problem, we derive the equivalent magnetic dipole moment of a circular aperture. Closed-form expressions of dipole moments are derived. Also, for the special case of axisymmetric excitation where the dipole moment vanishes, we develop a quadrupole model to describe the aperture behavior. The effectiveness of the obtained expressions is verified by comparisons with accurate analytical solutions in special cases and the exact solutions in integral form.

Nonrelativistic ferromagnetotriakontadipolar order and spin splitting in hematite

We show that hematite, α−Fe2O3, below its Morin transition, has a ferroic ordering of rank-5 magnetic triakontadipoles on the Fe ions. In the absence of spin-orbit coupling, these are the lowest-order ferroically aligned magnetic multipoles, and they give rise to the g-wave nonrelativistic spin splitting in hematite. We find that the ferroically ordered magnetic triakontadipoles result from the simultaneous antiferroic ordering of the charge hexadecapoles and the magnetic dipoles, providing a route to manipulating the magnitude and the sign of the magnetic triakontadipoles as well as the spin splitting. Furthermore, we find that both the ferroic ordering of the magnetic triakontadipoles and many of the spin-split features persist in the weak ferromagnetic phase above the Morin transition temperature. Published by the American Physical Society 2024

Review of: "Magnetic dipoles in paramagnetic material do not have specific and regular orientation; as a result, these materials do not have magnetic properties"

Review of: "Magnetic dipoles in paramagnetic material do not have specific and regular orientation; as a result, these materials do not have magnetic properties"

High gain nested dielectric resonator rectenna based on higher order mode and magneto-electric dipole theory

In this paper, a high-gain nested dielectric resonator rectenna operating at 5.8 GHz based on the magneto-electric dipole theory is proposed. A nested structure is employed to achieve the required resonant frequency in a small dimension. And the higher order HE21δ mode of the dielectric resonator antenna (DRA) is excited by a vertical coaxial probe feeding, which is equated to a horizontal array of crossed magnetic dipoles, thus enhancing the gain. Then, two vertical metal posts are embedded inside the DRA, serving as electric dipoles to form a magneto-electric dipole array in conjunction with the magnetic dipoles, which suppress the excessive lobes of the DRA in HE21δ mode and hence enhance the maximum gain of the DRA to 9.8 dBi. A rectifier circuit with harmonic suppression is designed. By adding a short-circuit microstrip transmission line to the rectifier circuit, the second harmonic with infinite impedance is suppressed and reflected back to the diode for secondary rectification. The designed rectifier circuit is connected to the DRA to form a rectenna. The test result shows that the rectenna obtains a peak conversion efficiency of 43.9 % and an output voltage of 1.95 V at 5.8 GHz, which is suitable for wireless energy harvesting.

Demonstration of Magnetic Dipole–Dipole Interaction Using a Smartphone Pressure Sensor

Demonstration of Magnetic Dipole–Dipole Interaction Using a Smartphone Pressure Sensor